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TechnicalArticlesdedicated to france, host Country of PIANC’s AGA 2013

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KEY WORDS: construction par phases, batar-deau, palplanches, butonnage, câble de garde

MOTS-CLES: step-by-step construction, coffer-dam, sheet piles, shoring, ship impact protection cable

1. INTRODUCTIONLe programme interrégional d’aménagement de l’Oise, dont VNF assure la maîtrise d’ouvrage, avait pour objet de moderniser les ouvrages de navi-

gation situés entre Compiègne et la confl uence avec la Seine, soit 100 km de rivière navigable. Il prévoit principalement le remplacement des 7 barrages manuels de l’Oise par des ouvrages mé-canisés (cf. Figure 1), l’aménagement de passe-à-poissons au droit de ces ouvrages, ainsi que la modernisation des 14 écluses de l’Oise.

Les barrages de Venette et de Boran-sur-Oise sont les deux derniers barrages manuels à avoir été re-construits sur les sept barrages de l’Oise naviga-ble, après la mise en service des barrages de Creil (2004), l’Isle-Adam (2007), Pontoise (2008), Verbe-rie (2008) et Sarron (2009).

LES BARRAGES DE L’OISE: MODES CONSTRUCTIfS

DAMS ON ThE RIVER OISE: CONSTRUCTION PRINCIPLES

FRéDéRIC AURY

EMCC (Vinci Construction France)Siège de Rungis

E-mail: frederic.aury@vinci-construction.fr

PATRICK AMATHIEU

(EMCC (Vinci construction France), Agence de Villeneuve Le Roi

E-mail: patrick.amathieu@vinci-construction.fr

Figure 1: Aménagement de l’Oise

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Entièrement automatisés, les nouveaux barrages de l’Oise assurent une régulation efficace et sûre du plan d’eau, indispensable à la navigation et au développement du transport fluvial. Ils amé-liorent également les conditions d’exploitation et de maintenance des ouvrages et ils contribuent à fiabiliser l’alimentation en eau potable.

Enfin, en période de crues, ils permettent une ges-tion précise, rapide et synchronisée des manœu-vres afin d’assurer l’effacement des barrages et ne pas créer d’obstacle à l’écoulement des crues.

Les sept barrages de l’Oise ont fait l’objet d’un avant-projet unique qui garantit une homogénéité de conception propre à faciliter la maintenance. Les barrages à clapets ainsi conçus sont mécani-sés et automatisés, permettent une manœuvre simple, sécurisée, rapide et synchronisée.

Figure 2: Exemple de passe à poissons

Dès leur conception, les sept barrages de l’Oise ont été équipés de passes à poissons (cf. Figure 2: ouvrage permettant aux poissons migrateurs de remonter les cours d’eau) afin de rétablir la conti-nuité piscicole. L’entreprise EMCC a participé en 2005 et 2006 à la reconstruction des barrages de Pontoise et de l’Isle Adam, les plus proches de la confluence.

2. DESCRIPTION géNéRALE DES BARRAgESLes nouveaux barrages sont généralement consti-tués de trois passes hydrauliques dont deux princi-pales et une plus réduite, appelée pertuis ; cette dernière passe n’étant pas systématique pour les sept barrages. Le débouché linéaire hydraulique de chaque passe est de 33,00 m pour les passes principales et de l’ordre de 12,00 m pour le pertuis (cf. Figure 3).

La bouchure du barrage est obtenue à l’aide de 3 clapets dont l’axe de rotation est parallèle au barrage actuel, et qui permettront de réguler la

cote de la retenue normale amont à une valeur constante mais ajustable à 5 cm prêt, selon les be-soins de la navigation.

Le barrage de l’Isle Adam est constitué de 2 passes principales, d’un pertuis et d’une passe à poisson. Comme tous les autres barrages, il est implanté à l’amont de l’ancien barrage, là où la hauteur d’eau est maximum, de l’ordre de 5,00 m. Le bar-rage de Pontoise est constitué simplement de 2 passes navigables et d’une passe à poissons.

Figure 3: Barrage de Venette

Le principe de fonctionnement d’un barrage à clapets est le suivant (cf. Figure 4):

Dans chacune des passes, un volet métallique: le clapet, pivote sur une semelle en béton armé, c’est-à-dire le radier. Les clapets sont actionnés par des vérins. Commandés de manière automatique, ces clapets assurent une régulation du plan d’eau en maintenant une hauteur d’eau constante en amont du barrage, hors période de crues.

Lors des crues, le clapet est couché en fond de radier et le barrage est alors dit ‘effacé’ afin de ne pas créer d’obstacle à l’écoulement des crues.

Figure 4: Principe de fonctionnement d’un barrage à clapets

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3. PHASAgE DES TRAVAUXLes travaux prévus pour les barrages de l’Isle Adam et de Pontoise ont été réalisés en trois phases dis-tinctes entrecoupées d’une période hivernale (mi-novembre à mi-avril) à risque de crues pendant laquelle les travaux en rivière ont été interrompus.

En première phase: conception et mise en place du câble de garde lorsqu’il est prévu, puis réalisa-tion du génie civil de la première passe navigable de rive droite et pose du clapet correspondant, celui-ci devant pouvoir être manœuvrable par l’entreprise à la demande du maître d’ouvrage à tout moment une fois posé.

En deuxième phase: réalisation du génie civil de la deuxième passe navigable et du pertuis (lorsqu’il existe), pose des clapets correspondants et de leurs organes de manœuvre, mise en place des équipements de commande, de contrôle et de supervision, réalisation de la passerelle.

En troisième et dernière phase: démontage des équipements et superstructures du barrage actuel, démolition de ses piles et de ses culées, fi-nitions, remise en état des lieux et repli du chantier après mise en service du nouveau barrage.

4. MODE D’EXECUTION DES BARRAgESLa présence permanente de l’eau de la rivière impose un mode de réalisation adapté avec des travaux réalisés par phases distinctes.

Durant ces phases, l’ouvrage est construit dans la rivière, à sec et à l’abri d’ouvrages provisoires appelés batardeaux et constitués d’une enceinte

étanche en palplanches (cf. Figure 5 à la page suivant).

Compte tenu de la nature des sols et de la hauteur d’eau à soutenir, les palplanches ont des modules standards, voire assez faibles, généralement de type PU 12 à PU18 et de 12/13,00 m de longueur. Elles sont foncées de 7,00 à 8,00 m dans les alluvi-ons puis dans la craie à l’aide d’un vibrofonceur puis d’un marteau hydraulique.

Une fois la cote des palplanches atteinte, un ter-rassement est réalisé sous eau pour mettre à nu l’assise saine qui servira de fondation au barrage. Un béton de rattrapage entre le sol en place et le radier est mis en œuvre sous eau (béton immer-gé).

Néanmoins, la seule épaisseur de gros béton ne suffit pas à la reprise des efforts de soulèvement dus aux sous-pressions, notamment en phase de chantier, lorsque que la ‘boîte’ est vide. Cette sujétion conduit à la mise en œuvre d’éléments d’ancrage.

Ces ancrages sont constitués de pieux H de 7/8 m de longueur environ enfichés dans le sol.

Une fois ces pieux et le bouchon en béton effec-tués, un dispositif de butonnage vient ceinturer l’ensemble en tête de rideau afin de créer un ap-pui de rive aux palplanches.

Lorsque tout ce dispositif construit sous l’eau est en place (palplanches, ancrages verticaux, gros bé-ton, cadre de butonnage), l’enceinte peut être vidée en toute sécurité.

Le génie civil et les équipements du barrage sont construits à sec (cf. Figure 6).

Figure 6: Construction du génie civil et mise en place des équipements à sec

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Figure 5: Cinématique de construction d’un barrage sur l’Oise

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5. LES CABLES DE gARDE5.1. Le système NAVISTOP®

EMCC a mis au point un système de protection des barrages contre les chocs de corps flottants, dont les bateaux, il y a plus de 25 ans. Ce procédé breveté s’appelle NAVISTOP®.

C’est ce système qui a été mis en œuvre sur les barrages de L’Isle Adam et de Pontoise dans le cadre des marchés de reconstruction des bar-rages de l’Oise.

21 barrages sont équipés aujourd’hui en France et en Belgique de ce dispositif.

Le système NAVISTOP® est constitué d’un câble en aramide (fibres synthétiques) tendu en travers de la voie d’eau, qui permet d’absorber l’énergie cinétique incidente du corps flottant ou bateau venant s’engager dans le câble en trainant sur le fond un ensemble de corps-morts et de chaînes (cf. Figures 7 et 8).

Le dispositif NAVISTOP® est composé par :

• Un câble de retenue en aramide• Deux coffres d’extrémité (et éventuellement

des flotteurs intermédiaires)• Des amarres fusibles avec tensionneur intégré• De chaînes et corps-mort trainés sur le fond.

Figure 7: Dispositif NAVISTOP® , vue en plan

Figure 8: Dispositif NAVISTOP® , vue en perspective

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Le principe de fonctionnement est le suivant (cf. Figures 9 et 10):

Le bateau A dérivant heurte le câble de garde B mettant en tension le dispositif jusqu’à provoquer la rupture des fusibles d’amarrage C.

Les coffres flottants D maintiennent le câble de garde B hors d’eau. Ils entraînent dans leur sillage la chaîne pendeur E sur lesquelles sont accrochés les corps-morts F et les lignes de chaînes de traine g.

Les chaines pendeurs E, les corps-morts F, et les lignes de chaine de traine g sont trainés sur le fond de la rivière et absorbent l’énergie cinétique du navire en perdition ainsi qu’aux efforts du cou-rant sur un navire A perpendiculaire au courant.

Les fusibles C sont définis de manière à céder bien avant les limites de capacité des tensionneurs. Ainsi, en cas de déclenchement du dispositif, les tensionneurs restent dans leur plage de fonction-nement normale, et peuvent être réemployés lors de la remise en place du dispositif.

Figure 9

Figure 10

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5.2. Méthode de dimensionnement

5.2.1. Description de la méthode

Les calculs sont réalisés par itérations à l’aide d’un tableur Excel. Une itération correspond à un pas de déplacement constant du bateau égal à la distance de freinage disponible sur le nombre de discrétisations souhaité. Connaissant la vitesse ini-tiale du bateau, on utilise la définition de l’énergie cinétique pour calculer son énergie. Puis, à chaque itération on calcule la nouvelle énergie du bateau en soustrayant les pertes dues aux frot-tements des masses:

La connaissance du Ei nous permet de trouver la vitesse du bateau au pas i. Lorsque sa vitesse devi-ent nulle, nous notons la distance de freinage.

5.2.2. Calcul des distances, angles et positions

•Déplacementduconvoi(bordavantgauche):

•Distancedemiseentension(cf.Figure11):

Figure 11

Nous avons alors :

et:

•CalculdeladistanceB(cf.figure12):

Figure 12

Nous avons alors :

•Calculdesanglesa et δ:

On considère la chaîne pendeur comme un sys-tème de barres avec F la force de frottements du corps-mort et des chaînes de traine (cf. Figure 13):

Figure 13

En faisant l’équilibre global suivant l’horizontale nous obtenons:

Or par géométrie:

Soit:

Ce qui nous permet d’obtenir la valeur de a, puis la valeur de δ.

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•Systèmeentension:

Le dispositif est en tension lorsque :

•Calculdelapositionducoffre:

On commence par calculer la position du coffre à la mise en tension en s’appuyant:

Si le système n’est pas en tension, on utilise la con-naissance des positions initiale jusqu’à la mise en tension. Puis la position du coffre est le prorata de l’avancement du convoi entre sa position initiale et sa position à la mise en tension. C’est-à-dire :

Si le système est en tension, on suppose que le cof-fre se déplace du pas i au pas i+1 selon la direc-tion du câble au pas i+1 (cf. Figure 14).

Figure 14

On calcule:

On en déduit:

•Calculdelapositionducorps-mort:

Le corps mort est dans l’alignement du convoi et du coffre. On en déduit:

5.2.3. Calcul des forces mises en jeu

•Calculdel’énergiecinétiqueduconvoi:

Cm est le coefficient de masse ajoutée qui sert à prendre en compte l’eau qui se déplace avec le convoi.

Par itérations successives, on évalue, avec Ec0 = Ecini:

Le signe de la contribution des forces hydrody-namiques dépend du signe de la vitesse relative du convoi par rapport au courant.

•Forcehydrodynamiquesurleconvoi:

Avec CD le coefficient de trainée qui dépend de la forme du bateau. Pour un parallélépipède rect-angle on prendra CD=2.

•Forcedefrottementducorps-mortetdeschaînesde traine:

On prend en compte la contribution des frotte-ments et de la cohésion du sol:

On en déduit :

•Tensiondanslecâblederetenue:

Selon le schéma 3 elle vaut:

•Tensionmaximaledansleschaînespendeur:

•Effortsurlebateau:

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5.3. Les principales hypothèses:

Les principales hypothèses nécessaires au dimen-sionnement sont les suivantes:

• Les caractéristiques du navire (4 à 5.000 tonnes)• La vitesse du courant (environ 2 m/s)• Les niveaux d’eau de fonctionnement (5 à 10,00 m)• Les caractéristiques de frottement du sol consti-

tuant le fond de rivière (tgj avec j = 25 à 35 °)• L’espace disponible pour arrêter le navire (de

l’ordre de 100 m).

6. CONCLUSIONLes chantiers de reconstruction des barrages de l’Oise a nécessité, pour leur protection, de ba-tardeaux.

Les batardeaux, réalisés en palplanches, limitent le gabarit hydraulique de la rivière et gênent le passage des crues c’est pourquoi les travaux ont été réalisés en dehors des périodes de crues po-tentielles, d’avril à novembre.

Dans ces conditions, les délais globaux à pren-dre en compte pour la construction des barrages n’ont pu être inférieurs à 2 ans.

Des moyens nautiques (pontons, bateaux remor-queurs-pousseurs, barges, etc.) ont été nécessaires

pour construire les batardeaux en palplanches ainsi que pour mettre en place les équipements, en particulier les clapets.

Sous forme de cadres assemblant profilés H et tubes circulaires, les systèmes de renfort et de bu-tonnage des palplanches ont été conçus pour as-surer le passage du matériel et des équipements afin de ne pas modifier la structure des batardeaux en cours de chantier.

Les travaux étant réalisés en maintenant la navi-gation sur l’Oise, le travail à l’abri de batardeaux a nécessité la mise ne place de systèmes de pro-tection contre les erreurs de navigation ou les ‘ba-teaux fous’.

Le choix s’est porté sur la mise en place de câbles de garde. La conception du système a été lais-sée à l’initiative de l’entreprise. EMCC a proposé son système breveté et éprouvé depuis plus de 25 ans sur les rivières françaises et belges: le système NAVISTOP®.

7. REFERENCES - Site internet du service navigation de la Seine- Archives EMCC sur les barrages de l’Isle Adam

et de Pontoise- Publications internes EMCC sur le système NAVIS-

TOP®

The river Oise development plan, of which VNF is the owner, aimed at modernising the navigation-al constructions and structures located between Compiègne and the confluence with the river Seine. Amongst others, the replacement of 7 dams was planned for new expected traffic, in particu-lar with the new Canal Seine Nord Europe.

EMCC worked in 2005 and 2006 on the reconstruc-tion of the dams of Pontoise and l’Isle Adam, the closest to the confluence. These dams are mobile dams for water level regulation in the upstream reach. They consist of two main sections, one sec-ondary section with smaller width and a fish way. The new dams are established upstream of the old ones, where the water depth is maximum (about 5 m).

Because the river flow cannot be stopped com-pletely, works must be realised with a specific methodology, with distinct stages taking into ac-

count a 6 months winter interruption period (from November to April) for flash-flood risks. During these different steps, the dam is built on the river bed, inside temporary enclosures called ‘cofferdams’, creating a dry work environment. At each stage, only a part of the river is blocked by the cofferdam so that a continuous river flow is maintained during the works and navigation is not stopped.

Water tightness is a key issue in this type of works. Lateral water tightness is realised by means of steel sheet pile walls, and the bottom of the cofferdam is concreted underwater. This bottom concrete slab is anchored by means of driven piles in order to counterbalance bottom water pressure.

To protect the zone of dams during the works as well as in the course of exploitation against the floating objects and the ‘crazy’ boats, a specific device of ‘stop boat’ is planned in the upstream of dams.

SUMMARY

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Le programme d’aménagement de l’Oise, dont VNF a assuré la maîtrise d’ouvrage, avait pour ob-jectif de moderniser les ouvrages de navigation situés entre Compiègne et la confluence avec la Seine. Il prévoyait, entre autre le remplacement de 7 barrages en perspective des nouveaux trafics attendus avec le nouveau Canal Seine-Nord Eu-rope.

EMCC a participé en 2005 et 2006 à la reconstruc-tion des barrages de Pontoise et de l’Isle Adam, les plus proches de la confluence. Il s’agit de barrag-es mobiles destinés à réguler le niveau d’eau du bief amont. Ces barrages, constitués de 2 passes principales, d’un pertuis et d’une passe à poisson sont implantés à l’amont des anciens barrages, là où la hauteur d’eau est maximum, de l’ordre de 5,00 m.

La présence permanente de l’eau de la rivière im-pose un mode de réalisation adapté avec des travaux réalisés par phases distinctes entrecou-pées d’une période d’interruption hivernale de 6 mois (de novembre à avril) à fort risque de crues.

Durant ces phases, l’ouvrage est construit dans la rivière, à sec et à l’abri d’ouvrages provisoires ap-pelés batardeaux. Les phases distinctes ont pour but de laisser la rivière s’écouler par une partie du lit pendant que l’on exécute les travaux de l’autre partie. Le trafic fluvial ainsi que les captages d’eau peuvent ainsi être maintenus pendant les travaux.

La proximité immédiate de l’eau rend primordiaux les problèmes d’étanchéité. L’étanchéité laté-rale est assurée par la réalisation d’une ceinture étanche en palplanches métalliques et la permé-abilité du sol à l’intérieur du batardeau est quasi-ment annulée à l’aide d’un béton immergé. Pour une étanchéité totale, les sous-pressions sont blo-quées par un réseau d’ancrage en pieux battus.

Afin de protéger la zone des barrages durant les travaux ainsi qu’en cours d’exploitation contre les objets flottants et les bateaux ‘fous’, un dispositif spécifique d’arrêt du type ‘câble de garde’ est prévu à l’amont des barrages.

RESUME

Der Entwicklungsplan von VNF für den Fluss Oise hat zum Ziel, die Bauwerke für die Schifffahrt, die zwi-schen Compiegne und der Mündung in die Seine liegen, zu modernisieren. Unter anderem wurde für das zusätzlich erwartete Verkehrsaufkommen, insbesondere im Zusammenhang mit dem neuen Kanal Seine-Nordeuropa, vorgesehen, sieben Dämme zu ersetzen. EMCC arbeitete in den Jahren 2005 und 2006 an der Deichsanierung von Pontoise und l’Isle Adam, die dem Zusammenfluss am nächsten liegen. Bei diesen Deichbauwerken handelt es sich um be-wegliche Dämme für die Regulierung des Was-serstandes im oberen Flussabschnitt. Sie bestehen aus zwei Haupt- und einem Nebenabschnitt mit geringerer Breite und einem Fischpass. Die neuen Dämme werden oberhalb der alten Dämme er-richtet, wo die größte Wassertiefe herrscht (ca. 5 m).

Da die Flussströmung nicht komplett gestoppt werden kann, müssen die Arbeiten mit einer beson-deren Methode durchgeführt werden, die für plötz- lich auftretende Fluten unterschiedliche Schritte

vorsieht, unter Berücksichtigung einer 6-monatig-en Unterbrechungszeit im Winter (von November bis April). Während dieser verschiedenen Schritte wird der eigentliche Damm innerhalb eines tem-porären Fangedamms, einem sogenannten Kof-ferdamms (‚cofferdam’) im Flussbett errichtet, was für eine trockene Arbeitsumgebung sorgt. In jeder Bauphase wird nur ein Teil des Flusses durch den Kofferdamm abgesperrt, sodass eine kontinuier-liche Flussströmung aufrecht erhalten wird und die Schifffahrt nicht eingestellt werden muss.

Wasserdichtigkeit nimmt eine Schlüsselposition bei dieser Art von Arbeiten ein. Die seitliche Wasser-dichtigkeit wird mittels Spundwänden erzielt und der Boden des Kofferdamms wird unter Wasser be-toniert. Die Betonplatte wird mittels Rammpfählen verankert, um den Grundwasserdruck auszuglei-chen.

Um die Dammzonen während der Arbeiten sowie im Verlauf der Abgrabung gegen schwimmende Gegenstände und Fahrzeuganprall zu schützen, ist eine spezielle Vorrichtung eines ‚Bootstopps’ in den oberen Bereichen der Dämme geplant.

ZUSAMMENFASSUNg

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KEY WORDS: mud fl at, ecological engineering, 3-D modelling, monitoring network, working with nature

MOTS-CLES: vasière, génie écologique, modé-lisation 3D, réseau de mesures, œuvrer avec la nature

1. INTRODUCTION

The Loire is one of the three major estuaries on the French Atlantic seaboard. Over the past 200 years

it has undergone major development with a view to improving its navigability and making it safe for shipping. The bed has been deepened, intertidal zones and secondary branches haven fi lled in to allow the tide to propagate further and ships to sail upstream as far as the port of Nantes, over 50 km from the river’s mouth.

These projects have considerably modifi ed the hydro-sedimentary dynamics of the estuary, lead-ing in particular to a fall of several metres in low-water levels and greater saline intrusion. The phe-nomenon of fi ne sediment being trapped in the

RESTORATION Of ThE LOIRE ESTUARY: ThE RESULTS Of 20 YEARS Of STUDIES

RESTAURATION DE L’ESTUAIRE DE LA LOIRE: LES RéSULTATS DE 20 ANNéES D’éTUDES

PIERRE BONABERNARD PRUD’HOMME LACROIX

Groupement d’Intérêt Public (GIP) Loire Estuaire22, rue de la tour d’Auvergne 44000 NantesFrance

Tel: +33 (0)2 51 72 93 67E-mail: pierre.bona@loire-estuary.org

SéBASTIEN LEDOUXLUCIE THIEBOT

ARTELIA8, Avenue des Thébaudières44815 Saint-HerblainFrance

Tel: +33 (0)2 2809 1849E-mail: sebastien.ledoux@arteliagroup.com

RégIS WALTHERLUC HAMM

ARTELIA6, rue de Lorraine38130 EchirollesFrance

Tel: +33 (0)4 7633 4000E-mail: luc.hamm@arteliagroup.com

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form of a maximum turbidity zone and fluid mud has also been amplified due to asymmetric tidal propagation accentuated by morphological changes in the estuary, and especially the con-siderable depths in the shipping channel in the downstream section.

This disturbance of the river’s hydro-sedimentary behaviour has created problems in several ar-eas:

• anoxic conditions have had an effect on the liv-ing environment

• side branches of the river have become clogged

• it is difficult to manage water offtake for agricul-tural and industrial uses

• there has been an impact on the landscape in urban areas, etc.

Because of this, the various stakeholders launched an ambitious study and monitoring programme in the 1990s as part of the ‘Plan Loire Grandeur Na-ture’ development plan, which has been super-vised since 2000 by the ‘Groupement d’Intérêt Public Loire Estuaire’ [GIP LE, 2006]. The aim of this programme was to improve the knowledge about the estuary system, to define an agreed set of ob-jectives for improving the functioning of the estu-ary and to investigate restoration scenarios.

The ‘predictive modelling’ studies undertaken be-tween 1995 and 2000 provided an initial assess-ment of the situation and examined proactive intervention scenarios that led to the decision to study a hydraulic solution involving the construc-tion of a tidal barrier.

The ‘downstream predictive studies’ carried out between 2000 and 2006 provided a large number of field data and enabled a 3-D hydro-sedimen-tary model of the estuary to be built. They looked in greater detail at the ‘tidal barrier’ scenario and various alternative types of intervention in the context of a comprehensive ‘morphological’ res-toration scenario for the estuary. These were then evaluated [GIP LE, 2007] and it was decided to optimise the comprehensive scenario and launch an initial experimental phase.

These two points were included in the 2007-2013 pre-operational programme to restore the estua-rine section of the Loire downstream of Nantes [GIP LE, 2008], which is currently nearing comple-tion. This is a sustainable development project us-ing the concept of ‘Working with Nature’ advocat-ed by PIANC. It is based on objectives shared by the main stakeholders in the estuary area defined with a view to readjusting the balance between its main functions: economic activities, environment, urban development and amenities. It also involves consultation with users and local players in draw-ing up projects. Finally, it takes into account the effects of global warming.

This paper first recalls the main characteristics of the estuary and then the objectives and overall approach adopted in the studies. It then discusses the 2007-2013 pre-operational programme and ends with a presentation of the results obtained from the two comprehensive scenarios studied in greater detail, i.e. changes that will occur in the estuary by 2040 if nothing is done, and the mor-phological restoration scenario.

2. MAIN CHARACTERISTICS OF THE LOIRE ESTUARYRunning for 1,000 km, the Loire is the longest river in France. It has a catchment area of 117,000 km2

and flows into the Atlantic Ocean at Saint-Naz-aire. The tidal range at the river’s mouth reaches 5 m and tides run upstream as far as Ancenis, more than 90 km above Saint-Nazaire. Nantes, the larg-est city on the river, is 55 km upstream. The river’s discharge varies considerably from 100 m3/s during low-flow periods to 6,000 m3/s during major floods (the reference historic flood of 1910 reached 6,400 m3/s), with an average of 850 m3/s. The estuary is also subject to high tides and severe storms. Water quality in the estuary is considered to be relatively poor, with saline intrusion running beyond Nantes, 70 km upstream of Saint-Nazaire, and a large max-imum turbidity zone that can reach as much as 0.8 to 1 million tonnes of suspended mud.

The successive development projects implement-ed over the past 100 years or more have consid-erably modified the morphology of the estuary, as can be seen from the situations in 1870 (Fig. 1), 1947 (Fig. 2) and 2002 (Fig. 3).

Fig. 1: Situation of the estuary in 1870

Fig. 2: Situation of the estuary in 1947 (distances in metres)

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Fig. 3: Situation of the estuary in 2002 (distances in metres)

Fig. 4: Historic changes in high and low water levels in the estuary between 1903 and 2002

These projects began upstream and involved cre-ating a single inland navigation channel between Paimbœuf and Nantes dredged to -5 m CM (the marine chart datum (CM) corresponds more or less to the lowest water level at Saint-Nazaire) and extracting large quantities of sand (90 million m3) from the low-water bed of the river upstream of Nantes between 1915 and 1993. In the 1980s a deep-water port was built downstream on the right bank between Saint-Nazaire and Paimbœuf and an outer access channel was deepened to -12.5 m CM as far as Paimbœuf (Fig. 3). All these works transformed the original wide estuary with its multiple channels into a narrow one with a single channel. A double-channel system is still visible, however, between Paimbœuf and the ocean, though there is little exchange between the branches, which behave independently. One of the consequences of these works has been to lower the low water levels in the estuary. At Nant-es, 52 km from Saint-Nazaire, the drop between 1903 and 2002 was more than 4 m (see Fig. 4).

3. OBJECTIVES OF THE COMPREHENSIVE STUDY APPROACH3.1. Objectives

The objectives originally defined in 1998 were re-evaluated in 2005 and redefined in the context of the Water Framework Directive (WFD) insofar as this relates to the transitional water bodies formed by estuaries. The WFD aims primarily to determine the ecological condition of water bodies not sim-ply on the basis of chemical criteria but by incor-porating criteria linked to the living environment and morphological condition of rivers. It aims to achieve good ecological status by fixed dates (2015, 2021, 2027, etc.), or at least good potential for highly modified water bodies such as the Loire estuary, determined by appropriate ‘good status’ indicators.

In the current state of discussion and work to define such indicators for estuaries, the approach devel-oped by the WFD emphasises the importance of criteria such as fish resources, benthic resources, the extent of mud flats in particular in mesohaline areas, the size and position of maximum turbidity zones and the extent of anoxic crises (cf. BEEST programme).

It should also be pointed out that the programme of measures defined by the river basin committee with a view to improving the status of the estu-ary water body is based on the restoration pro-gramme. It is thus possible to distinguish:

1. Objectives directly linked to the good ecologi-cal status of the water body, which are gov-erned primarily by the size of the maximum tur-bidity zone and the distance it travels:

• Improvement in water quality for the needs of drinking supplies, industry and agriculture.

• Maintenance/improvement of biological re-sources in the estuary through its function as a nursery for flatfish and transition area for fish, which is governed by oxygenation of the wa-ter, etc.

• Maintenance of fisheries and the resultant farming activities.

2. Objectives relating to environmental mainte-nance or restoration:

• Improvement of nursery functions for flatfish and as a stopping place for wintering birds; these depend on the mud flats.

• Improvement of spawning functions further upstream.

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3. More general objectives connected with the social and urban functions of the estuary, in-cluding improved relations between urban ar-eas and the river, the visual appearance of the river and the development of water and river usage.

Finally, restoration was conditional upon a num-ber of factors:

• changing port functions: development down-stream, prospects for reducing draughts in the Nantes channel;

• the need not to aggravate flooding, in par-ticular in the Nantes urban area.

3.2. Investigation of Solutions

3.2.1. Hydraulic Regulation of the Estuary by a Tidal Barrier

The solutions tested at the time with regard to the estuary were consolidated into different scenarios. The so-called ‘disconnection’ scenario appeared to be the one that provided the best response to the objectives defined, and in particular for rais-ing low-water levels at Nantes by 3 m. This sce-nario was based on the construction of a gated flow-regulation structure situated downstream of Nantes at kilometre point 38, to reduce the oscil-lating volume of water that propagates upstream as far as the city. The principle of this structure was to create a reservoir at low tide, which would then disappear at high tide and during floods. The fact that it reduced the oscillating volume of water would have a favourable impact on the retreat of the saline wedge and turbidity.

The principles for operating the structure, the pre-ferred location at the Martinière site and very gen-eral geometrical aspects were defined in predic-tive modelling studies between 1995 and 2000. In 2000, at the end of this process, the stakeholders adopted the principle of taking this scenario fur-

ther by examining its feasibility and impacts, and also expressed their desire to seek an ‘alternative’ scenario owing to its high cost and non-progres-sive character.

3.2.2. Progressive Restoration: the Morpholog-ical Scenario

Various consultants (Delft Hydraulics, HR Walling-ford, expert committee, etc.) were involved in the exploratory phase between 2004 and 2005. This re-vealed that it was possible to develop an alterna-tive to the tidal barrier scenario, focused more on modifying the sedimentary dynamics of the estu-ary by combining measures to adapt its geometry and the progressive restoration of environments with important biological functions. This change in the approach to restoration was initiated by Delft Hydraulics and the European expert committee mobilised at the time by the GIP Loire Estuaire. It was based on consideration of the asymmetric nature of tidal propagation in the estuary and on improved knowledge of its functioning.

This type of approach represented a real alterna-tive to the tidal barrier scenario and in this respect it provided encouraging results. Even so, it did not fulfil all the objectives, in particular with regard to raising the low-water level by 3 m at Nantes. The studies carried out in 2005 and 2006 aimed to give concrete expression to this type of intervention by identifying realistic solutions.

Two solutions were proposed (see Fig. 5 below):

• The creation of intertidal mud flats, located up-stream of Paimbœuf. These would ‘store’ flood tides penetrating into the estuary. The other ad-vantage of this type of operation is ecological: environments that had receded considerably during the past century would be recreated.

• Raising the bed in the Nantes channel, which is now deeper than necessary for shipping.

Fig. 5: The two solutions that now constitute the morphological restoration scenario for the estuary

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3.3. Use of a 3-D-Model for the Hydro-Sed-imentary Evaluation

Since the studies began in 1995, numerical mod-elling has been an important means of analysing field data, understanding the physical processes occurring in the estuary and exploring the various solutions proposed during the successive studies. An important step forward was taken in 2006 with the setting up of a first version of a comprehen-sive three-dimensional hydro-sedimentary model capable of reproducing the major vertical strati-fication that influences the current fields, salinity and turbidity in the estuary, along with the deposi-tion, erosion and consolidation processes affect-ing mud at the bottom of the river, which can be several metres thick. This model was calibrated us-ing a considerable amount of data obtained from field surveys conducted by the GIP LE between 2000 and 2004. It showed in particular that the morphological changes observed in the sandy bed of the river could not by themselves explain the 3.5 m drop in low-water levels at Nantes. There would also have to be a major reduction in bed friction resulting from a layer of fluid mud several tens of centimetres thick. Consequently, any simu-lation of the various solutions would have to com-bine calculations of both the water surface curves and the dynamics of the mud layer [Walther et al., 2007 ; Walther et Hamm, 2008].

This first version of the model provided an initial vi-sion of the estuary’s functioning in the current situ-ation, based on a trend scenario involving no out-side intervention. It was then used to explore the impact of different solutions and thereby define a morphological restoration scenario.

A second version of the model was then devel-oped in 2008-2009. This included the following im-provements: integration of areas subject to sub-mersion by tides between Nantes and the sea, refinement of the strategy for defining the vertical

grid, improvement of friction maps, taking into account the presence or absence of fluid mud on the estuary bed, improvement of the vertical turbulence model to represent saline and turbid stratification more accurately and improvement of parameter definition for all the mud erosion, deposition and consolidation laws. Two important new results were obtained with this model:

• On the one hand, by developing and validat-ing new parameters for the vertical turbulence model, it was possible to reproduce more pre-cisely the saline intrusion episodes observed particularly at low water during neap tides, as measured by the permanent SYVEL continu-ous monitoring network operated by the GIP LE since 2007 [Walther et al., 2009];

• On the other hand, by improving the empirical model of deposit consolidation and erodibility and defining parameters for mud floc fall veloc-ity by including the local turbulence produced by flow depending on shear stress, it was possi-ble to reproduce the dynamics of the maximum turbidity zone/fluid mud system over a period of a year more accurately [Walther et al., 2012]. Fig. 6 shows a comparison between in situ moni-toring of the position of the fluid mud in the in-land channel and the numerical simulation for the year 2007 covering the entire estuary.

4. THE 2007-2013 PRE-OPERATIONAL PROgRAMME4.1. Overview

The study approach introduced by the GIP LE for this pre-operational programme includes various components aimed at answering the many ques-tions of operational feasibility not addressed by conventional engineering practice:

Fig. 6: Left: measurement of the position of fluid mud depending on discharge in the Loire. Right: result obtained by numerical modelling

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• Evaluation of the effectiveness of different solu-tions with regard to estuarine systems involving complex processes that depend in addition on climate change.

• The permanence of the works and the resultant changes in morphological balances.

• The ecological effects of such operations.• The different uses of the sites (agriculture, hunt-

ing, hydraulic management, ecological func-tions, etc.).

• Its feasibility from the technical and legal stand-points, but also in terms of the operational back-ing of a project of general interest.

The study approach included two types of analysis in order to address these questions:

• Re-evaluation and refinement of the compre-hensive morphological scenario defined in 2006 and of the trend scenario without any interven-tion up to the year 2040, based on knowledge gained since 2006 and in particular on improved hydro-sedimentary modelling tools and better knowledge of hydro-climatic changes, in order to confirm or rule out the need to act and the relevance of the solutions, and also to examine questions of long-term feasibility.

• Examination of the feasibility of the proposed so-lutions. With regard to the mud flats, the proce-dure was taken to an advanced level of defini-tion in order to measure and identify all aspects of the operation’s feasibility.

The study strategy pursued since 2008 is based on the various components described below.

4.2.DefinitionofBaselineSituationsandAcquisition of Data Required for the Project

Investment in this area aimed to improve knowl-edge in various fields: the physical operation of the mud flats, by monitoring their sedimentary dynam-ics; characterisation of ecological functions asso-ciated with the mud flats (birds, benthos, fish, etc.) via data acquisition and processing; knowledge of the physical operation of the estuary (sediment inflows, sediment behaviour, etc.). The aim was to obtain reference information in order to guide the design of the works, enable them to be evaluated and refine the tools used. It was also necessary to obtain information on the study area governing the feasibility of an experimental mud flat. This in-volved detailed characterisation of habitats liable to be affected and an analysis of materials likely to be disturbed during the works.

4.3. Development and Application of Evaluation Tools

As part of this programme, in 2008 and 2009 the GIP LE reused the hydro-sedimentary model de-veloped in the framework of the previous pro-

gramme, as it was necessary to have a sufficiently reliable study and evaluation tool that would re-duce the uncertainties surrounding these fields and could be used predictively.

Similarly, the model of the Loire estuary’s ecologi-cal functions developed by the GIP LE was used for the ecological assessment. This GIS-based mapping system helps to evaluate the impact of development works on the estuary’s ecologi-cal functions by monitoring various representa-tive species. It was used to assess the ecological effects of the experimental intervention work by comparing gains and losses in the estuary’s eco-logical functions.

4.4. Updating and Optimisation of Comprehensive Scenarios

To provide assistance in decision making, the study programme included an evaluation of the trend scenario, representing the absence of any major restoration work and the likely morphologi-cal and hydro-climatic changes that will occur by 2040, and of the comprehensive morphological scenario defined in 2006. This was updated and re-evaluated during the study phase in light of prog-ress in the feasibility studies for the experimental operation and optimised by defining the various solutions more clearly.

4.5. Design of the Experimental Mud Flat and Consultation

A specific aim was to make progress with the fea-sibility study for the experimental mud flat. This involved adopting a similar approach to that proposed by PIANC in its ‘Working with Nature’ re-search programme [PIANC, 2008]. It included the following four stages:

i) Defining project requirements and objectives. This stage was carried out in the context of the ‘downstream predictive studies’.

ii) Understanding the environment. This stage in-volved numerous series of measurements in the field, hydro-sedimentary modelling and use of a model of the estuary’s ecological functions. For the experimental operation, this meant ini-tially determining a preferred site on the right bank between Donges and Cordemais and performing an exhaustive analysis.

iii) Constructively involving all stakeholders in or-der to identify ‘win-win’ situations. A working group of players and users was set up by the GIP LE for this purpose, comprising represen-tatives of government agencies, the Nantes – Saint-Nazaire port authority, the Coastline Conservation Authority (‘Conservatoire du Littoral’), environmental protection associa-tions, farmers, hunters and marshland users’ federations. This group met five times to define

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specifications for the operation, allowing for the various usages found in the area, and then to evaluate the proposals put forward by the consultants in charge of designing the experi-mental mud flat. Contributions to this process included the design studies for the mud flat and specific work to assess its implications for the farming profession.

iv) Preparing proposals/initial designs for the proj-ect to meet navigational and environmental requirements. The comprehensive solutions de-fined in 2006 in fact took navigational require-ments into account as a project constraint. Two alternative schemes covering a hundred hectares were defined for the experimental operation, taking into account the specifics of the site, constraints connected with usage and the objectives defined.

The permanence of the works was studied in depth. In particular, it appeared necessary to en-sure dynamic exchanges of water between the mud flats and the meadows situated behind them in order to encourage flow on to the mud flats, a necessary condition for maintaining them. Studies performed on the two sites also showed that it was possible to design a scheme in which both the mud flat and the channels created to connect it with the meadows behind had every chance of lasting provided such exchanges were guaranteed.

The experimental works indeed indicated that the mud flats would contribute to the restoration of the estuary, but they did not cover a large enough area to produce a sufficient effect on hydro-sed-imentary processes in the estuary. The overall ef-fect of the project on the ecological functions of the estuary was positive, but it also had significant impacts on existing ecosystems that would prob-

ably require mitigating measures (see details in Bona et al., 2012). The process also helped to de-fine the technical and legal feasibility of such a scheme.

5. UPDATINg AND FINE-TUNINg OF THE COMPREHENSIVE SCENARIOS5.1. The Trend Scenario without any Intervention

This scenario includes an estimation of the mor-phological changes occurring in the estuary by the year 2040 in the absence of any new devel-opment, coupled with a climate change scenario in which the average sea level would rise by 0.2 m and the low flow and mean discharge of the Loire would fall.

The trend scenario for the estuary gives an im-portant insight into the stakes involved in this pro-gramme. Roughly, it leads to a rise in sea level, upstream incursion of salinity and of the maximum turbidity zone, as well as the prospect of a reduc-tion in the surface area of the mud flats.

All of this would:

• harm water quality and affect offtake and de-pendent biological functions;

• modify flood risks: these would be aggravated in the downstream part of the estuary, with floods rising to near historic levels or reference levels considered up to now for town planning in the Nantes urban area;

Fig. 7: The two sites studied

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• weaken the trophic functions of the estuary, by reducing the surface areas of the mud flats;

• increase submersion risks for meadows on islands in the Loire; such changes pose the question of how far the current farming system is able to adapt.

5.2. The Comprehensive Morphological Scenario

The principles identified in 2006 were translated into a comprehensive scenario including the creation of 515 ha of mud flats and raising of the bottom of the Nantes channel to an average elevation of -5 m CM. The comprehensive scenario, identified in 2006 and re-evaluated in 2010, provides an ef-fective answer to the various objectives defined. It counteracts the effects of the trend scenario and improves the present situation. The development works considered have a significant positive ef-fect on the status of the water body (namely by causing the maximum turbidity zone and salinity to retreat further downstream and raising the low-water level) while restoring the areas of major im-portance for the estuary’s ecology.

The questions raised by the downstream programme and in particular the amount of funding needed in the medium term (€ 190 million) led the GIP Loire Estuaire to examine the effectiveness of the com-prehensive development scenario in greater detail and especially to define the minimum investment needed to fulfil the objectives initially considered, or at least some of them. A detailed analysis of the various solutions revealed that:

• actions consisting of raising the bed upstream of Nantes have little influence on the estuary downstream of Nantes;

• actions limited to raising the bed of the Nantes channel would require a certain ‘artificialisa-tion’ of the estuary in order to be morphologi-cally stable (building of structures, addition of very coarse materials). To be effective they would be expensive (costing € 60 million-€ 300 million) and therefore appear to be unsuitable (in terms of cost, technical feasibility and statu-tory compliance);

• the creation of mud flats is the main lever for acting on the estuary’s hydro-sedimentary sys-tem. Different extents of mud flats were evalu-ated with respect to indicators connected with the objectives sought (availability of water re-sources with less than 1g/l of salt; incursion of the maximum turbidity zone into the Nantes channel).

An area of 250 ha of mud flats would have little ef-fect in relation to the trend situation whereas an area of 340 ha would produce convincing results: smaller maximum turbidity zone in the Nantes chan-nel, salinity slightly reduced in comparison with the trend situation, gain in mud flats. This ‘optimised’

scenario represents long-term investment of € 128 million. The benefits to be obtained from a larger area of mud flats would be limited, whereas actions to raise the bed elevation (morphological scenario) would reinforce the effects of the mud flats.

Fig. 8: Change in main indicators in relation to the present situation

The different tests performed give a clearer idea of the minimum intervention threshold (340 ha) needed to obtain a tangible effect in response to all the objectives of the programme and in partic-ular those connected with the status of the estuary water body.

6. THE RESULTS OF TWENTY YEARS OF STUDIESThe Loire estuary is certainly one of the most stud-ied in Europe thanks to a succession of scientific programmes and studies that have been carried out. Initially (1993 and 1994) these produced a precise assessment of the degradation suffered by the estuary over the past century as a result of work to improve its navigability.

‘Predictive modelling’ was carried out from 1995 to 2000 and ‘downstream predictive studies’ were implemented from 2000 to 2006 with a view to de-fining a restoration programme. Two approaches were considered: a conventional approach in-volving the building of a structure and a ‘mor-phological’ approach working on the geometry of the estuary. The latter, which produces results much more slowly but was considered to be cura-tive and resulting in a satisfactory state of equilib-rium, was finally preferred to the former, which was viewed as palliative and resulting in ‘artificialisa-tion’ of the estuary.

A detailed and precise understanding of the physical, biological and social environment of the estuary proved to be essential for this second approach. This led the stakeholders involved in the estuary to create the GIP Loire Estuaire, the main role of which was to define and manage a set of indicators representative of characteristicphenomena in the fields of hydraulics, sedimento-

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logy, water quality, natural heritage and land use, and to use the original results obtained from the in-dicators or specific studies in communicating with an informed, aware public concerning the state of the river and its estuary. Major measurement campaigns have been implemented since in the field since 2000 and a permanent network of six multi-parameter sensors (SYVEL) was set up in 2007 to provide continuous monitoring of water quality in the estuary. These data represent a capital of knowledge that is essential for understanding the functioning of the estuary.

The GIP LE was then assigned new tasks, one of which was to perform predictive studies down-stream of Nantes in order to find and then imple-ment a sustainable scenario for restoring the estu-ary. This stage of investigating, finalising, optimising and then evaluating different scenarios was based to a great extent on a comprehensive 3-D hydro-sedimentary numerical model of the estuary capa-ble of accurately reproducing the physical process-es that govern the dynamics of water movement, salinity and turbidity, but also of evaluating differ-ent development solutions. The challenges posed by the estuary meant that various innovations were needed in order to finalise the model and the results finally obtained were validated by a committee of European experts, thus underscoring the quality of the work carried out. The model provided a clearer understanding of the current functioning of the es-tuary and helped in evaluating the impact of differ-ent types of intervention.

The pre-operational programme initiated in 2007 has taken the issue a stage further. The approach now being considered is a similar one to that rec-ommended by PIANC in its document on ‘Working with Nature’, where it takes a clear stand on this matter. This considers project objectives primarily from the point of view of the natural system rather than from that of technical design and lays em-phasis on prior consultation with all the stakehold-ers involved.

At the present time, the comprehensive restoration scenario adopted is an ambitious one, as it aims to re-establish more balanced hydro-sedimentary dynamics throughout the estuary. Extensive – and very expensive – work is to be carried out, involv-ing the re-creation of around 340 ha of intertidal mud flats. It is for this reason that a first experimental stage has been studied and is still being discussed at the present time. The feasibility study has already shown the ecological advantages of such an op-eration while at the same time underlining its tech-nical, ecological, legal and social complexity.

7. REFERENCESBona, P., Prud’homme Lacroix, B., Walther, R., Rivier, A., Rieu, J., David, E. and Hamm, L. (2010): “Amé-

lioration du fonctionnement hydrosédimentaire de l’estuaire de la Loire: leviers d’intervention et mo-délisation hydrosédimentaire tridimensionnelle”, La Houille Blanche, n°6, 25-32.

Bona, P., Prud’homme Lacroix, B., Ledoux, S., Thié-bot, L., Walther, R. and Hamm, L. (2012): “Développe-ment de leviers d’intervention pour la restauration de l’estuaire de la Loire: Avancées et perspectives”, Comptes-rendus du colloque Grands Aménage-ments Hydrauliques, Paris, 14-16 November 2012, CD-ROM published by the Société Hydrotechnique de France.

GIP Loire Estuaire (2006): “Etudes Prospectives aval, Tome 1: les objectifs, un nouvel équilibre pour l’estuaire de la Loire”, Loire Grandeur Nature Pays de Loire inter-regional programme, 2000-2006.

GIP Loire Estuaire (2007): “Etudes Prospectives aval, Tome 2: les scénarios, Une démarche progressive pour l’estuaire de la Loire”, Loire Grandeur Nature Pays de Loire inter-regional programme, 2000-2006.

GIP Loire Estuaire (2008): “Etudes Prospectives aval, Tome 3: les orientations, Un programme opérationnel pour l’estuaire de la Loire”, Loire Grandeur Nature inter-regional programme.

Hamm, L. and Walther, R. (2008): “Morphodynamic coupling of bottom roughness and fluid mud for modelling tidal propagation in the Loire estuary (France)”, Proc. 31st International Conference on Coastal Engineering (ICCE 2008), Hamburg, World Scientific, Vol. 3, 2832-2841.

PIANC (2008): “Œuvrer avec la nature/Working with Nature”, Position paper de la commission EnviCom, October 2008, revised January 2011, Available from http://www.pianc.org/edits/wwnpositionpaper.htm Accessed 31 January 2013.

Walther, R., Bertrand, O., Rieu, J. and Hamm, L. (2007): “Modélisation tridimensionnelle de la salinité et de la turbidité dans l’estuaire de la Loire: couplage des processus”, La Houille Blanche, n°4, 47-55.

Walther, R., Rivier, A., Rieu, J., David, E. and Hamm, L. (2009): “Modélisation tridimensionnelle hydro-sédi-mentaire de l’estuaire de la Loire – Evaluation de modèles de turbulence verticale”, Comptes-rendus des journées de l’Hydraulique – congrès annuel de la Société Hydrotechnique de France “Morphody-namique et gestion des sédiments dans les estuaires, les baies et les deltas”, Paris, September 2009 (avail-able on CD-ROM from the SHF).

Walther, R., Schaguene, J., Hamm, L. and David, E. (2012): “Coupled 3D modelling of turbidity maxi-mum dynamics in the Loire Estuary, France”, Proc. 33rd International Conference on Coastal Engineer-ing (ICCE 2012), Santander, 1-6 July 2012, Coast-al Engineering Proceedings, 1(33), sediment.22. doi:10.9753/icce.v33.sediment.22.

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Like most of the major European estuaries, that of the Loire underwent extensive development in the 20th century with a view to improving its navigabil-ity. The work carried out in the context of such de-velopment seriously disturbed the hydro-sedimen-tary processes of the estuary, leading in particular to a deterioration in water quality in terms of salin-ity and suspended sediment and considerably re-ducing the areas occupied by intertidal mud flats, which are an important habitat in the ecosystem. This realisation led stakeholders to undertake an ambitious programme of studies and river monitor-ing work in the 1990s, the principal stages of which

are recalled here. The main results have been the introduction of an estuary indicator observation network, the development of a comprehensive ‘morphological’ restoration scenario for the estu-ary whereby the mechanisms that trap sediment in the inner estuary are reduced while at the same time restoring the estuary’s major ecological func-tions, and the development of a pre-operational approach whereby work can be implemented in a progressive, concerted manner on the basis of an experimental programme currently being dis-cussed.

SUMMARY

Comme la plupart des grands estuaires euro-péens, celui de la Loire a connu sur le dernier siè-cle des aménagements majeurs visant à améliorer sa navigabilité. Les travaux réalisés ont fortement perturbé le fonctionnement hydrosédimentaire de l’estuaire et conduit à dégrader notamment la qualité des eaux en termes de salinité et de matières en suspension et à réduire fortement la surface occupée par les vasières intertidales qui constituent un maillon important de l’écosystème. Ce constat a conduit les acteurs estuariens à engager dans les années 1990 un programme d’études et de suivi ambitieux du fleuve dont nous

retraçons ici les principales étapes. Les principaux résultats acquis sont la mise en place d’un réseau d’observation d’indicateurs estuariens, la mise au point d’un scénario global de restauration ’mor-phologique‘ de l’estuaire permettant de diminuer les mécanismes de piégeage de sédiments dans l’estuaire interne tout en restaurant des fonctions écologiques majeures de l’estuaire ainsi que le développement d’une approche pré-opéra-tionnelle permettant une réalisation progressive et concertée à partir d’un programme expérimental en cours de discussion.

RESUME

Wie die meisten großen europäischen Ästuare hat auch das der Loire im 20. Jahrhundert im Hinblick auf die Verbesserung der Schiffbarkeit eine weitrei-chende Entwicklung durchgemacht. Die Arbeiten, die im Zusammenhang mit einer solchen Entwick-lung durchgeführt wurden, haben die Hydro-Se-dimentationsprozesse im Ästuar erheblich gestört, was insbesondere hinsichtlich des Salzgehalts und der gelösten Sedimente zu einer Verschlechterung der Wasserqualität geführt hat und zu einer erheb-lichen Reduzierung der Wattbereiche, die einen bedeutenden Lebensraum innerhalb des Öko-systems darstellen. Die Durchführung dieser Arbe-iten veranlasste Interessengruppen in den 1990er Jahren dazu, ehrgeizige Studienprogramme und

Monitoring am Fluss durchzuführen, deren Haupt-etappen hier wiedergegeben werden. Die we-sentliche Ergebnisse führten zu der Einführung eines Ästuar-Indikator-Beobachtungs-Netzwerks, der Entwicklung eines umfassenden ‘morphologis-chen‘ Wiederherstellungszenarios für das Ästuar, in dem jene Mechanismen reduziert wurden, welche das Sediment im Inneren des Ästuars binden, während zur gleichen Zeit die wesentlichen ökolo-gischen Funktionen des Ästuars wiederhergestellt und ein funktionsfähiger Ansatz entwickelt wurde, wodurch die Arbeiten in einer fortschreitenden, aufeinander abgestimmten Weise auf der Basis experimenteller Programme, die kürzlich diskutiert wurden, durchgeführt werden können.

ZUSAMMENFASSUNg

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KEY WORDS: wide-gauge canal, regional devel-opment, environment, public-private partnership, performance criteria

MOTS-CLES: canal à grand gabarit, développe-ment régional, environnement, partenariat public-privé, critères de performance

1. INTRODUCTIONMajor transport infrastructure projects such as the Seine-Nord Europe Canal primarily fulfi l an eco-nomic role. Such projects must enable the over-all transport system to improve its competitiveness and enhance effi ciency of logistics chains in the European economy. In the case of the Seine-Nord Europe Canal, this means linking the North of France to the 20,000 km of waterways in the Euro-pean wide-gauge network.

The improvement to the transport network will have a positive impact on the competitiveness of the areas the canal passes through. Its proxim-ity to one of the major commercial axes should strengthen the competitiveness of import and ex-port activities by regional businesses and attract new industrial activities as it is these that stand to gain the most from waterway transport. This will thus contribute to the re-industrialisation of the re-gions that have in some cases been abandoned by this type of activity. In addition, the installation of four new multi-modal platforms connected to the road and rail networks will draw activities that

have not traditionally had relations with water-ways. As the fi nd economically viable solutions in waterway transport, they will opt for modal shift.

2. THE STAKES FOR ECONOMIC AND INDUSTRIAL DEVELOPMENT OF THE CANALThe European Seine-Scheldt river link project rep-resents a new system for the transport of goods between France, Belgium, The Netherlands and Germany, situated at the heart of a wide-gauge waterway network that serves the major econom-ic centres of northern Europe. This area is char-acterised by intense cross-border fl ows of goods and by one of the highest levels of saturation of road transport on the north-south axis. The Seine-Scheldt link includes several sections in France and Belgium, which, once the wide-gauge Seine-Nord Europe Canal is in operation, will join together to create a single major wide-gauge river link.

Although development work has been underway since 2000 on the North and South parts of the link, in both France and Belgium, the Seine-Nord Europe wide-gauge canal to be built between Compiègne and Aubencheul-au-Bac is the cen-tral link of the Seine-Scheldt connection, which was selected as one of the thirty priority projects for the Trans-European Transport Network (RTE-T) in 2004.

ThE SEINE-NORD EUROPE CANAL – ACCOUNTING fOR MULTI-PURPOSE APPLICATIONS

Of ThE wATERwAY IN ThE PARTNERShIP CONTRACT

CANAL SEINE-NORD EUROPE – PRISE EN COMPTE DE LA MULTI-fONCTIONNALITé DE

LA VOIE D’EAU DANS LE CONTRAT DE PARTENARIAT

BENOÎT DELEU

Deputy Director Direction of European waterways and Innovation, VNF175, rue Ludovic Boutleux 62400 BéthuneFrance

Tel.: +33 3 21 68 83 62E-mail: benoit.deleu@vnf.fr

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Seine-Nord Europe means the creation of a new 106 km canal through two French regions: Picardie and Nord-Pas-de-Calais, whose technical char-acteristics match the European waterway classi-fication for navigable waterways of international concern known as ‘class Vb’.

It is made up of the following features:

- eight reaches connected by seven locks with a drop height of between 6.4 and 30 metres, equipped with water-saving basins;

- two reservoir basins for water supply during low-flow periods;

- three aqueducts including one 1,330 metres long enabling crossing of the Somme;

- four multi-modal platforms and seven quays to serve as cross-over points with other modes of transport (road and rail);

- five reception facilities for community and indi-vidual pleasure boating.

The Seine-Nord Europe project is part of a broader

approach towards both development and com-petitiveness for the region, reducing the environ-mental impact of transport and enhancing the multi-purpose functions of waterways. The project meets several public policy objectives:

- eliminating the major bottleneck on the Euro-pean wide-gauge waterway network;

- improving the competitiveness of businesses by making the advantages of water transport available to them;

- strengthening the integration of the Great Pari-sian Basin and Nord-Pas-de-Calais into the core of the European economy and contributing to regional development;

- supporting the development of French maritime ports by developing their hinterland;

- developing the accessibility of goods at the heart of major agglomerations;

- rooting sustainable development stakes in trans-port policies;

- enhancing the hydrological and tourism advan-tages offered by waterways.

Fig. 1: The Seine-Nord Europe Canal – central link of the Seine-Scheldt connection

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3. REgIONAL PLANNINg AND DEVELOPMENT PERSPECTIVES FOR THE PROJECTOne of the main features of the economic influ-ence of the project for the regions it crosses lies in the creation of activity zones to be supported by the future canal: multi-modal port zones, loading docks and agricultural storage and shipping plat-forms. These are to be spread across four large-scale port activity zones intended for industrial and logistics usage. Cambrai-Marquion, Péronne Haute Picardie, Nesle and Noyonnais.

Fig. 2: The four platforms of Seine-Nord Europe

These four platforms benefit:

o Enlargement of the hinterland of French mari-time ports

o New provisions for massified logistics, that will be able to take advantage of the inter-modality to be set up between maritime, waterway, rail and road transport

o The competitiveness of businesses in the French regions of Picardie, Nord-Pas-de-Calais and the greater Parisian basin

The construction of the Seine-Nord Europe Canal also enables the development of other activities, of which the most significant relate to water tour-ism (river cruises and private boating), the supply of raw water to agglomerations in the North of France and the production of renewable energy.

• Waterway tourism: All of the tourist activities brought about by the opening of the canal could generate a total turnover of € 46.5 million in 2020. The associated added value is estimat-ed at 15 % of the turnover according to predic-tions, being € 7 million.

• Supply of raw water: The agglomeration of Lille is currently supplied by the Chalk aquifer (50 mil-lion m3), the Carboniferous aquifer (20 million m3) and rivers water (15 million m3). These resources may prove insufficient in about ten years’ time, especially during dry years. Studies carried out during the preliminary project phase confirmed the possibility of transferring 1 to 2 m3/s from the Oise basin to the North of France with a view to strengthen the prospects for the supply of drink-ing water to the North of France.

• Production of renewable energy: Recovery of the land running alongside the canal offers potential for the production of wind and photo-voltaic energy or from biomass.

4. ENVIRONMENTAL INTEgRATION FOR THE PROJECT4.1. A Project that Respects Water Resources

Preserving Resources

The hydraulic design of the canal has been set as a high performance objective, with the aim of sav-ing water as a key priority. To this end, the canal will be fitted with a sealing system, whose average permeability should not exceed the equivalent of a 30 cm layer with a permeability coefficient of 10 -8 m/s. The locks themselves will be equipped with water-saving basins and water recycling systems. All of these measures will allow the 106 km-long ca-nal to consume a maximum of just 1.2 m3 water/s, including evaporation and safety margins. The second essential point regarding hydraulic design aims to develop a supply scheme that is respectful of natural surroundings and other uses. The Oise has been selected as the only sup-ply source because of the good quality and hy-draulics of the water. The canal will be supplied through continuous drawing from the Oise, re-source permitting, which is to say once the flow of the Oise stays above a threshold flow that takes into account the needs of the surrounding area and uses. In the event of low-flow on the Oise, wa-ter storage in two reservoir basins guarantees the supply to the canal. The water intake has been positioned as far downstream as possible on the water course, nearest to the confluence with the Aisne, in order to keep the impact on the natural stretch of the Oise and the Natura 2000 area to a minimum, protecting the valley.

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As a new water body, the Seine-Nord Europe Ca-nal has a duty to achieve its ecological potential. The Oise was also chosen as the source of the water supply for this reason, thus guaranteeing a good quality supply. In order to preserve the quali-ty of the resource for the length of the canal, water renewal is considered from the reservoir basins.

4.2. A Project for a Living Canal, Integrated into the green and Blue Belts

A Project Designed to Limit the Impact on Bio-diversity

The Seine-Nord Europe Canal project has been designed in accordance with the ‘Avoid, Reduce, Compensate’-approach which must currently guide all development projects. This approach is based on the principle of integrating environ-

mental issues into the design data for the project, on the same level as other technical or financial items. Primarily, this means designing the project is such a way as to avoid environmental impact as far as possible, including for the choice of the most fundamental decisions regarding the project (nature of the project, location, etc.). With this in mind, the design plans for the Seine-Nord Europe Canal have made it possible, to draw up a route with minimal impact, avoiding sites of interest and sensitive natural habitats as far as possible (for ex-ample, in the river Sensée sector).

Where passing through sensitive areas has been unavoidable, integration measures have been put in place to limit the impact of the project. In this way, a 1,330 m long aqueduct will cross the valley of the river Somme, respecting the continuity of the ecological corridor made up by the river.

Fig. 3: Diagram showing the water supply for the Seine-Nord Europe Canal

Fig. 4: Photomontage of the river Somme aqueduct (©VNF-Archivideo)

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Finally, the compensatory measures are defined according to the residual impact. The equiva-lence between the loss and compensation will be not only quantitative (surface), but also calculat-ed in terms of quality (biodiversity) and ecological functions.

A range of compensatory measures has thus been planned to off-set the impact of the various types of environment and habitats affected. In addition to ‘heavy’ ecological development in some sec-tors for the re-construction, rehabilitation or res-toration of functional environments, preservation action for existing areas as well as lighter develop-ments, such as planting hedges, creating ponds, building roost boxes, nest boxes or shelters for chi-roptera or birds.

By way of example, the area of forest that would have to be cleared to make way for the construc-tion of the project is estimated at around 70 ha. Reforestation will be carried out at a ratio of 4:1, making around 280 ha, including 1/1 for ecologi-cal objectives and 3/1 for forestry objectives. Re-garding wetlands, the off-set area should be at least 1.5 times the affected area, making more than 135 ha for the 90 ha affected.

4.3. A Project for a ‘Living Canal’ in order to Achieve the WFD Objectives

In order to meet the requirements for good eco-logical potential set by the Water Framework Di-rective (WFD), specific ecological installations such as 25 km of lagooned embankments and hydrological extensions are planned. They will en-able the development of different species of flora and fauna, fulfilling the role of the ‘green lung’ of the canal. This innovative design of the embankments and extensions will allow the canal to develop live characteristics. Given the good design and good management, these areas could offer a very di-verse environment for flora and become a sanc-tuary or a zone for breeding and nurturing young for a large number of animal species, particularly aquatic species. The methods for maintaining and managing these new spaces will then become the key to their ecological efficiency and durability.

4.4. A Human Project Integrated into its Surroundings

Use, Landscape and Heritage

The Seine-Nord Europe Canal will represent a new axis that cuts across and joins together the territo-ries it passes through. The change in usage and trade in the region has therefore been integrated as a key challenge in the construction of the ca-nal.

As regards integration into the landscape, respect for the identity of territories has been set as a prior-ity. This work, together with the architectural han-dling of the structures, to which it is closely linked, has been entrusted to designers recognised by their peers. Designing the identity of the project and the shape of the landscape development policy will be coherent with the ecological stakes mentioned above.

Finally, preservation of the cultural heritage has been integrated into the consideration of the en-vironmental challenges. In this way, the diagnos-tic studies and archaeological digs have already been carried out along the proposed path in or-der to identify remains.

In the impact study presented in 2007, VNF made a commitment to setting up an environmental observatory in order to monitor the effect of the project on the main environmental features. In the report, the public inquiry supported this commit-ment and insisted on the idea that the observato-ry should be “set up as early as possible in order to carry out an inventory before beginning work and to be able to then monitor the progress of the work and their impact on the natural surroundings”.

This observatory was established in 2009. It is made up of independent experts, whose expertise cov-ers the main effects of the project on the environ-ment, representatives of State services in charge of water, ecology and town and country planning policies.

Its goal is to guarantee the integration of the proj-ect within the surrounding area in the long-term and verify the implementation and efficiency of the compensatory measures proposed, to ensure transparency between all of the stakeholders. The works are structured around three committees who are responsible for issues relating to water re-sources, biodiversity and landscape respectively.

5. THE PARTNERSHIP CONTRACT AND THE PERFORMANCE CONTROLOpting for a partnership contract enables optimi-sation of the cost of the project and a reduction to the construction time. These contracts meet the demands of a commitment in terms of duration and quality of the service provided to users and the upkeep of infrastructure. In addition, putting together groups of private partners makes it pos-sible to pool highly specialised expertise in a range of areas that are specifically adapted to the vari-ous functions of the project, on a European level, both in terms of construction and in terms of the whole range of services made available to the market and the region by the time the canal is

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opened, thanks to the multi-purpose functions of the waterway.

This tool also enables overall management of com-plex projects, by integrating infrastructure as well as the additional activities related to it into the same contract. The project benefits from the develop-ment of associated economic activities put for-ward by the private partner through the ‘competi-tive dialogue’ procedure.

The competitive dialogue gives private partners and the public entity the opportunity to gradually optimise the project, in order to come to the best suitable solution for the project in controlled risk conditions. This discussions and exchanges pave the way for the implementation of new and inno-vative solutions.

The Seine-Nord Europe partnership contract is built on performance objectives that measure the qual-ity of service offered to users, the quality of the up-keep of the infrastructure and, last but not least, the control of the environmental impact.

The performance objectives linked to transport aim to guarantee transport time for vessels traveling along the link. These objectives are based on an average transit time and on requirements regard-ing availability of the structures.

Traffic simulations carried out on a flow model devel-oped by the Centre d’Etudes Techniques Maritimes

et Fluviales (French Institute for Inland and Maritime Waterways) have shown that he average journey for a wide-gauge fleet was 17 hours and that 90 % of the fleet covered the length of the canal in less than 21 hours. This data is solid, fitting with the volume of traffic except where the locks approach saturation point. These values have therefore been maintained in order to characterise the canal oper-ating performance. The partner must abide by the performance up to the saturation threshold they present in their bid. When the saturation threshold is reached, VNF and the partner agree to define new performance objectives in light of the situation or to double the number of locks.

The reliability and availability objectives aim to guarantee that the infrastructure remains open to navigation. A distinction is made between closure of the canal for offline periods on the one hand and unforeseen interruptions due to problems with operating the structures on the other. The reliabil-ity and availability objectives have been set based on the past experience of wide-gauge waterway managers on a European level.

For offline periods, the objectives distinguish be-tween annual offline periods for carrying out pre-ventive maintenance operations and night-time interruptions enabling more frequent and shorter operations. The periods reserved for annual offline periods are shorter in the initial years of the structure following the installation adjustment period. This has

Table 1: Performance criteria for availability of the link

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been set at eight days per year, based on experi-ence from the Rhone, while retaining the possibility of carrying over a certain proportion of the allocat-ed time from one year to the next.

A summary of these availability objectives is shown in the table on the previous page.

Reliability objectives emerge from the statistics on wide-gauge structures in Belgium and Germany. The main objective involves limiting interruption to the fl ow of traffi c along the canal to less than 100 hours per year, which would mean 99 % reliability across the whole link. The number of stoppages is also limited in order to limit disruption for users and to encourage the partner to return to using of the waterway, even in downgraded mode. A distinction is drawn according to the duration of stoppages. The number of stoppages of between 3 and 8 hours is limited to 7. At the most, a stop-page of 8 hours is permitted provided that it does not go beyond 3 days.

The performance objectives cover the condition of the structures for the duration of the contract. The partner and VNF have the indicators of the operating condition of the structures stipulated in the contract. This operating condition indica-tor characterises the suitability of the structures for correct operation.

In terms of the environment, waterproof seal per-formance is taken into account, as part of the wa-ter-saving approach explained above, as are wa-ter quality, quality of implementation of ISO system

14 001, renewable energy production and energy consumption.

The waterproof seal indicator measures loss through infi ltration. Checks can be carried out each year during the offl ine period with direct measurement of the lowering of the water course. The cost of penalty fi nes is fi xed in such a way as to encourage the partner to identify the location of leakages and carry out repairs.

The water quality indicators aim to ensure that the ecological potential of the canal is maintained alongside the quality of raw water for the produc-tion of drinking water.

The energy indicators aim to ensure operational effi ciency of the canal, according to traffi c, on the one hand, i.e. the total electricity consump-tion with regard to a contractually agreed refer-ence and minimum production of renewable en-ergy on the other.

Finally, the contract provides for indicators that measure user satisfaction. This more qualitative measurement is based on satisfaction surveys and on the duration of intervention by the partner for incidents beyond their control (accidents, load losses, etc.)

These performance objectives are quite close to those established on the PIANC report 111 on the defi nition of performance indicators for water-way networks. Indeed, the parts relating to transit time or crossing time though locks, the reliability of

Table 2: Type of performance indicators for the Seine-Nord Europe partnership contract

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locks, etc. are also found here. The PIANC WG 111 report indicators are broader as they cover the entire transport chain, including port services and are intended for use by institutional stakeholders in order to determine the overall efficiency of the transport system.

In conclusion, the Seine-Nord Europe Canal com-bines several economic, social and environmen-tal functions. The partnership contract is a suitable format for the completion of this complex project

as it enables control over a number of different objectives, arising from an initial dialogue with the stakeholders, within a contractual framework. Performance measurement is ensured through the monitoring of indicators and gives rise to an assessment each year. These mechanisms aim to provide users or other beneficiaries with the ‘best’ possible quality of service, while taking into ac-count progress in the field of waterway manage-ment.

As a frontline project for trans-European trans-port networks, the Seine-Scheldt link will ensure a wide-gauge waterway connection from the Seine basin through to the Scheldt and Rhine basins. Seine-Nord Europe is a sustainable development project. Environmental integration means special consideration for economic management of wa-ter resources and is underpinned by the principle of working with nature to develop solutions that respect the natural surroundings. The realisation of Seine-Nord Europe through a partnership contract enables a commitment to be made regarding the

performance of the structure and offers guaran-tees as to maintaining the infrastructure in good condition over time.

This article presents the Seine-Nord Europe Canal, which is at the heart of the Seine-Scheldt link, and provides information about the functions the ca-nal fulfils as well as the principles of environmen-tal integration. The article explains how the vari-ous functions of the canal are taken into account in the performance objectives of the partnership contract.

SUMMARY

Projet prioritaire des réseaux transeuropéens de transport, la liaison Seine-Escaut assurera la con-nexion fluviale à grand gabarit depuis le bassin de la Seine jusqu’aux bassins de l’Escaut et du Rhin. Seine-Nord Europe est un projet de développe-ment durable. L’insertion dans l’environnement apporte un soin particulier à la gestion économe de la ressource en eau et retient le principe de travailler avec la nature en développant des so-lutions respectueuses des milieux naturels. La ré-alisation de Seine-Nord Europe en contrat de partenariat permet d’avoir un engagement sur les

performances de l’ouvrage et donne des garan-ties sur le maintien en bon état de l’infrastructure dans la durée.

Dans cet article, on fera une présentation du canal Seine-Nord Europe au sein de la liaison Seine-Escaut, on donnera des indications sur les fonctions assurées par ce canal ainsi que sur les principes de son insertion environnementale, en-fin, on décrira comment les différentes fonctions du canal sont prises en compte dans les objectifs de performance du contrat de partenariat.

RESUME

Als ein Projekt in vorderster Front des transeuropä-ischen Transportnetzwerks wird die Seine-Schel-de-Verbindung eine weiträumige Wasserstraßen-verbindung vom Seinebecken bis zur Schelde und dem Rheinbecken sicherstellen. Seine-Nordeuro-pa ist ein nachhaltiges Entwicklungsprojekt. Die In-tegration von Umweltbelangen stellt eine beson-dere Herausforderung für das wirtschaftliche Management der Wasserressourcen dar und wird unterstützt von dem Prinzip „Working with Nature“, um Lösungen zu entwickeln, die das natürliche Umfeld berücksichtigen. Die Umsetzung des Seine-Nordeuropa-Projekts mittels eines Partnerschafts-

vertrags erlaubt eine Verpflichtung bzgl. der Lei-stungsfähigkeit der Anlagen und bietet Garantien, dass die Infrastruktur während der Lebensdauer in einem guten Zustand gehalten wird.

Dieser Artikel stellt den Seine-Nordeuropa-Kanal vor, der sich im Zentrum der Seine-Schelde-Verbin-dung befindet, und liefert Informationen über die Funktionen, die der Kanal erfüllt, ebenso wie über die Grundsätze zur Einbindung der Umweltbe-lange. Der Beitrag erklärt, wie die verschiedenen Funktionen des Kanals bei den Leistungszielen des Partnerschaftsvertrags berücksichtigt wurden.

ZUSAMMENFASSUNg

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KEY WORDS: Mont-Saint-Michel, hydraulic works, hydro-sedimentary studies, dam, hydraulic fl ushing

MOTS-CLES: Mont-Saint-Michel, aménagements hydrauliques, études hydrosédimentaires, barrage, chasses hydrauliques

1. LE PROJET DE RETABLISSEMENT DU CARACTERE MARITIME DU MONT-SAINT-MICHELL’opération de rétablissement du caractère mari-time du Mont-Saint-Michel entre dans sa dernière phase de travaux qui porte sur la réalisation des aménagements hydrauliques à l’aval et à l’amont du nouveau barrage sur le Couesnon jusqu’à l’anse de Moidrey. Ces travaux devraient s’achever en 2015 après la mise en service du pont-passerelle et la destruction de la digue-route.

Celle-ci fut contestée dès sa construction en 1879: « Nous avons une chose unique au monde, si belle qu’on ne la peut imaginer quand on ne l’a pas vue. Un bijou de granit, un colosse de dentelle, une merveille incomparable encadrée dans un paysage d’une invraisemblable beauté, dans un golfe de sable jaune, s’étendant à perte de vue. Les ingénieurs sont arrivés qui ont fait une digue. La digue menace le monument et doit faire pousser des choux dans la mer de sable qui semble, au soleil couchant, un océan d’or », écrivait Guy de Maupassant en 1884.

Cet ouvrage s’inscrivait dans la logique de la pol-dérisation de la baie lancée en 1769 par Quinette de la Hogue qui obtint une concession de 2000 hectares et poursuivie par la Compagnie des Pol-ders de l’Ouest à la fi n du 19ème et au début du 20ème siècle. Jusqu’en 1969, date de construc-tion de l’ancien barrage sur le Couesnon, les aménagements dans la baie ont eu pour effet d’accélérer son colmatage par des sédiments et de rapprocher les bancs d’herbus du rocher sur lequel se dresse l’abbaye du Mont-Saint-Michel.

AVANCEMENT DU PROJET DE RéTABLISSEMENT DU CARACTèRE MARITIME DU MONT-SAINT-MIChEL

PROGRESS Of ThE RESTORING OPERATION Of ThE MONT-SAINT-MIChEL’S MARITIME ChARACTER

ROMAIN DESgUéEBRUNO LEgENDRE

Syndicat Mixte Baie du Mont-Saint-Michel2, rue du PrieuréBP 2950170 ARDEVONFrance

E-mail: M. Desguée: r.desguee@rcm-mtstmichel.frE-mail: M. Legendre: b.legendre@rcm-mtstmichel.fr

JOËL L’HER

CETMEF, Centre d’études techniques maritimes et fl uvialesTechnopôle Brest-IroiseBP 0529280 PLOUZANÉFrance

E-mail: joel.lher@developpement-durable.gouv.fr

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Le projet actuel est lancé en 1995, après de nom-breuses tentatives portées par diverses commis-sions. Trois objectifs lui sont fixés:

• rendre à la marée et aux sables l’espace occu-pé par la digue et les parcs de stationnement,

• libérer les abords du Mont-Saint-Michel de la présence des voitures,

• assurer un accès permanent au Mont tant pour les besoins des visiteurs que pour les Montois.

Les études de définition se déroulent jusqu’en 2001. D’importantes études hydrosédimentaires sont menées pour répondre à l’objectif de rétab-lissement du caractère maritime en exploitant au mieux les forces de la marée et la puissance de chasse du Couesnon. Un modèle physique hy-drosédimentaire de 24 m sur 48 m est notamment construit par la SOGREAH pour tester différents aménagements. Les études s’appuient aussi sur l’important effort de recherches hydrosédimen-taires mené depuis les années 1970 qui a fait pro-gresser considérablement la connaissance scien-tifique de la baie du Mont-Saint-Michel.

Un projet est établi et validé en 2000 par une com-mission scientifique présidée par Fernand Verger. La déclaration d’utilité publique (DUP) est pronon-cée le 21 juillet 2003. Les aménagements hydrau-liques prévoient la construction d’un nouveau barrage permettant la pénétration de la marée dans le Couesnon pour assurer des chasses avec des volumes renforcés par l’aménagement du Couesnon et la création d’un réservoir dans l’Anse de Moidrey. Par ailleurs, un seuil hydraulique per-met de partager le Couesnon en un bras à l’Ouest et un bras à l’Est du Mont.

Les travaux commencent en 2005 et, en 2006, le projet est confirmé avec quelques aménage-ments optimisant les épis, le positionnement du chenal Ouest, la longueur du pont-passerelle et la position du seuil de bipartition du Couesnon.

Pour conseiller le Maître d’Ouvrage aux différ-entes étapes de la réalisation du projet un co-mité de suivi hydrosédimentaire est constitué en juillet 2007. Ce comité présidé par Pierre-Louis Viollet, a dans un premier temps, recommandé le développement d’un modèle numérique de transport sédimentaire. L’outil construit à partir d’un maillage géométrique de la baie, calcule en différents points des paramètres (hauteur d’eau, vitesse, concentration) en simulant la dynamique sédimentaire par des lois physiques. Le comité a suivi le développement de cet outil qui malgré sa sophistication à la pointe de l’état de l’art actuel, reste loin de pouvoir fournir des certitudes compte tenu de la complexité des phénomènes modéli-sés. Le comité l’a néanmoins exploité pour étayer les avis que lui a demandé le Maître d’Ouvrage sur différents questionnements, tels que la lon-gueur du pont-passerelle, le cône hydraulique de

chasse dans la baie, l’aménagement de l’anse de Moidrey, l’optimisation des points de rejets de la tangue issue des terrassements à l’aval du bar-rage, etc.

Fig. 1: Schéma global des aménagements programmés

2. LE BARRAgE SUR LE COUESNONOuvrage d’art à part entière, construit entre 2006 et 2009, l’architecture du barrage intègre toutes les dimensions d’un site où nature, technique et culture se rencontrent de façon exceptionnelle. Elle concilie une juste inscription dans le grand paysage de la baie, mêlant les fonctionnalités techniques de gestion des eaux et des espaces publics de découverte et de contemplation.

Partie intégrante de la baie, en relation sensible avec le Mont Saint-Michel, le barrage s’inscrit dans une dimension culturelle profonde qui entre en résonance avec le génie du lieu et l’imaginaire collectif qui s’y rattache.

2.1. Principes de conception: entre équipements hydrauliques et espaces de contemplation

Au-delà de sa fonction première de régulation

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des eaux, le barrage est conçu, dans toutes ses dimensions, pour prendre en compte et révéler le caractère exceptionnel du site. Dans sa fonction-nalité hydraulique, le projet est dessiné à partir du principe dit de ‘la vanne-secteur’, dont la géomé-trie se déduit des contraintes de gestion des eaux. Pour des raisons à la fois techniques et architec-turales, les huit ensembles de vannes implantés à l’amont du barrage, côté Couesnon, permettent de libérer face à la mer et au Mont une perspec-tive dégagée sur le paysage.

Dans sa dissymétrie, l’ouvrage propose, en com-plément des équipements hydrauliques, la créa-tion d’espaces publics majeurs au-dessus des eaux: face au Mont, le pont-promenade et le balcon maritime offrent au public un espace de contemplation unique. La perspective s’ouvre sur le Mont. Au sud, côté terre, ils permettent de con-templer le fleuve canalisé et l’efficacité méca-nique des équipements en mouvement régulier.

2.2. Les équipements hydrauliques

Le projet est dessiné à partir du principe classique de la vanne-secteur. Chacune des huit vannes est actionnée par deux vérins hydrauliques. L’entité homogène que forment la vanne-secteur, ses deux bras et les deux vérins qui les actionnent, constitue de par sa spécificité et sa mobilité cy-clique l’élément original du projet ; sa répétitivité dans les huit passes du barrage lui confère une im-portance singulière.

Fig. 2: Dessin des vannes secteurs et réalisation finale

Le dessin de l’armature des vannes renvoie aux formes circulaires des instruments de marine com-

me les sextants, en référence au déplacement cy-clique des astres qui anime les marées. La poussée horizontale des vérins qui actionnent les vannes joue dans la direction contradictoire du mouve-ment des eaux de mer et des eaux du Couesnon.

L’ensemble cylindrique que forment les seize roues dans la perspective du barrage est directement appréhendable depuis le pont-promenade par le public.

Fig. 3: Schémas du barrage et détails de la maquette des vannes secteurs

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La rotation des vannes permet d’assurer le remp-lissage par ‘sur-verse’ (par-dessus la vanne) pour limiter les apports de sédiments et de vidange par une ouverture progressive en ‘sous-verse’ (sous la vanne), ainsi que l’ouverture hydraulique totale, en fonction du jeu des marées et du mouvement des eaux du Couesnon.

2.3. Les espaces ouverts au public

Le pont-promenade est traité comme un espace de déambulation, de liaison entre les deux berges du Couesnon, en continuité de plain-pied avec les chemins aménagés sur les digues est et ouest. Une grande qualité de prestations est conférée à son traitement architectural: transparence du garde-corps côté terre, ossature en acier peint, ‘bastingage’ en bronze, allège coupe-vent en verre sérigraphié, finition du sol en béton désac-tivé et insertion d’éléments de granit, suivant la trame du barrage.

Fig. 4: Schémas du barrage et détails de la maquette des vannes secteurs

Le balcon maritime est dessiné comme un espace suspendu, projeté vers le Mont, sur cette ligne de partage symbolique entre baie et intérieur des

terres, entre puissance des éléments naturels et mécanique de régulation ; le seul endroit de la baie au-dessus des eaux, avec le futur pont-passerelle, où il soit possible de demeurer lors des marées hautes. Le garde-corps du balcon mari-time forme une sorte de longue table cintrée telle un bastingage, en figure de proue au-dessus des eaux, face au Mont Saint-Michel. Devant le grand paysage de la baie, il est couronné par un pupi-tre de bronze linéaire : le pupitre des lettres. Sur sa surface sont gravés les quatre alphabets qui ont fondé l’histoire écrite de l’Europe, dont le Mont Saint-Michel demeure un des repères vivants: les alphabets hébreu et arabe, s’écrivant d’Est en Ouest ; les alphabets grec et latin, d’Ouest en Est.

2.4. La technicité du barrage

D’une longueur totale de 138,46 m culées com-prises et d’une largeur maximale de 32,4 m (por-tée maximale du balcon maritime), le barrage est équipé de 8 passes de 9 m de largeur hydraulique chacune et de 2 écluses à poissons de 3,10 m de large, situées de part et d’autre de l’ouvrage. Constitué de 9 piles de dimensions variables (23 à 27m pour 1, 8 m de large), il est étanche jusqu’à la cote: 9,40 m IGN 69.

Fig. 5: Vues amont du barrage, vannes ouvertes

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La fonctionnalité première de cet ouvrage est de redonner au Couesnon une force suffisante pour éroder les fonds sédimentaires aux abords du rocher en effectuant régulièrement des lâch-ers d’eau. L’efficacité hydraulique des remplis-sages et vidanges, dépend du débit d’apport du Couesnon fluvial et du niveau de la mer. Son cycle de fonctionnement, décrit ci-dessous, est dicté par le rythme des marées: les remplissages fluvio-maritimes débutant 10 minutes avant l’heure de pleine mer, les lâchers d’eau, 6 heures plus tard.

Les 8 vannes du barrage fonctionnant dans les deux sens, elles permettent, en phase de remp-lissage, de limiter les apports de sédiments dans les parties amont de l’ouvrage: les entrées d’eau se font alors par sur-verse. A l’opposé, au mo-ment des lâchers d’eau, les écoulements se font par sous-verse, permettant ainsi au courant pou-vant atteindre 100 m3/s, de nettoyer le radier de l’ouvrage et d’ainsi reprendre les sédiments dépo-sés en amont de ce dernier.

3. LES AMENAgEMENTS HYDRAULIQUES Le nouveau barrage ne saurait, à lui seul, restituer toute sa puissance au Couesnon, mais conjugué à des aménagements hydrauliques, il donnera à nouveau au fleuve la force perdue au fil des ans depuis plus de quarante ans. Les aménage-ments hydrauliques prévus à l’amont et à l’aval du barrage vont en effet aider ce dernier à agir plus efficacement pour redonner au Couesnon la force d’emporter au loin du Mont les sédiments et d’entretenir un environnement maritime autour des remparts.

3.1. Les aménagements à l’amont du barrage

L’ensemble des aménagements hydrauliques amont est réalisé sur une période de 4 ans, de septembre 2011 à début 2015. Après le nettoyage

et l’élagage préalables des berges, réalisés début 2010, le fond du lit du Couesnon est curé. Cette opération porte sur les 4,7 km de fleuve situés à l’amont du nouveau barrage, jusqu’à l’anse de Moidrey. Ces travaux, qui consistent à extraire 455.000 m3 de sédiments permettront, à terme, d’obtenir un volume de stockage de 800.000 m3 dans le lit du fleuve.

En complément du dragage du lit du fleuve, l’anse de Moidrey, progressivement comblée au fil du temps, se voit modifiée pour devenir une véritable réserve en eau. Pour lui rendre cette capacité, un réservoir hydraulique d’une capacité de 300.000 m3 est reconstitué à travers 36 ha de canaux (9 km au total, pour 700.000 m3 de matériaux extraits) sur les 86 ha qu’elle compte.

Avec l’ensemble de ces travaux, le Couesnon retrouvera une capacité de stockage de près d’1,1 million de m3 d’eau en moyenne, pour des marées de coefficient 95 ; pouvant aller jusqu’à un volume de 1,4 millions de m3 d’eau stockés lors des périodes de très grandes marées.

Ces différents travaux vont conduire à extraire du lit du Couesnon et de l’anse de Moidrey quelque 1,2 million de m3 de tangue. Grâce à sa teneur en calcaire, ce sédiment gris argenté, mélange de sablons et de débris coquillés, propre à la baie du Mont-Saint-Michel, s’avère être un excellent complément minéral pour les terres agricoles des polders. Il permet également de satisfaire plu-sieurs centres équestres intéressés pour utiliser ce matériau adapté aux articulations des chevaux. Différentes pistes de valorisation locale de ce sédiment ont donc été étudiées. L’ensemble de ces matériaux excédentaires sera alors, tout au long de ces 4 années de chantier, utilisé pour le rechargement de parcelles agricoles environ-nantes, l’amendement de certaines parcelles et le rechargement de centres équestres. Au final, l’intégralité du matériau sera valorisée locale-ment, cette valorisation faisant partie intégrante de ces travaux hydrauliques amont.

Fig. 6: Principe simplifié de fonctionnement du barrage

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Fig. 7: Dragage dans le Couesnon, décapage des exhaussements et terrassements

dans l’Anse de Moidrey

3.2. Les aménagements à l’aval du barrage

Fig. 8: Image de synthèse des résultats escomptés dans l’estuaire du fleuve Couesnon

Les travaux d’aménagement hydrauliques aval, débutés en septembre 2011 s’étalent sur 4 an-nées. Dans le cadre de ces travaux, une partie des cordons d’enrochement qui enserraient le Couesnon est démantelée. Ils servent à la réalisa-tion d’un seuil de partage qui serpente sur 2 km, depuis le barrage jusqu’au pied du Mont, afin de mieux guider l’action des lâchers d’eau. Les deux chenaux Ouest et Est ainsi formés garantiront une

bonne répartition des chasses du barrage de part et d’autre du Rocher.

Pour compléter ces aménagements, des épis dé-flecteurs et écarteurs accompagneront et faciliter-ont la divagation du Couesnon sur les grèves. Les courants circuleront ainsi plus facilement et plus fortement autour du Mont, empêchant les sédi-ments de se déposer toujours au même endroit.

Les aménagements hydrauliques à l’aval du nou-veau barrage sur le Couesnon nécessitent différ-entes techniques de dragages très particulières, qui sont de plus réalisées dans un environnement très contraignant (interventions en fonction des marées, des débits du Couesnon et de la ges-tion du nouveau barrage). Les interventions ont en effet lieu à la fois dans le lit du fleuve et sur les herbus, pour permettre de remanier au total plus de 850.000 m3 de sédiments. Ces derniers sont soit réutilisés sur le site (remblaiements de fouille, ré-alisation de nouveaux ouvrages, etc.), soit évacu-és, pour 400.000 m3 environ, par la technique du ‘dragage à l’américaine’, qui est régulièrement à l’œuvre dans les ports industriels.

Fig. 9: Pelle amphibie et travaux hydrauliques en aval du barrage

Cette technique consiste, après extraction, à relâcher les sédiments directement dans le lit du fleuve Couesnon, pendant les périodes de lâchersd’eau du barrage et pendant la marée descen-dante afin de bénéficier d’une évacuation vers le large grâce à l’action du courant. Cette méthode est utilisée aussi bien pour des sédiments extraits du lit du Couesnon, après traitement préalable (aspi-ration dans l’eau et triage par un godet cribleur

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aspirateur de type REMU), que pour les sédiments extraits des herbus. Tous les volumes sont donc soit transportés vers un atelier de dragage où les sédi-ments seront mélangés avec de l’eau sous pres-sion avant d’être rejetés dans le fleuve via une canalisation flottante, soit évacués directement au moyen d’une pelleteuse amphibie équipée du godet REMU. Au final, contrairement aux amé-nagements hydrauliques à l’amont du barrage, l’intégralité des matériaux excédentaires sera soit réutilisée directement sur site, soit évacuée au fil des lâchers d’eau du barrage et des marées de-scendantes, l’obligation étant de n’exporter au-cun matériau vers l’extérieur du site.

Fig. 10: Vue sur la structure métallique du futur pont-passerelle entre le continent et le Mont,

dont la mise en service est prévue pour le printemps 2014

4. EN CONCLUSIONLe caractère singulier exceptionnel du Mont-Saint-Michel et de sa baie, « double œuvre de la nature et de l’art », comme l’écrivait Victor Hugo, impose des conditions particulières à la réalisation des travaux pour la requalification durable de ses abords. Aujourd’hui, alors que le chantier est en-core en pleine activité, le visiteur peut déjà perce-voir le début de la concrétisation des objectifs visés par les promoteurs du projet, avec la libération de l’abord du Mont de la présence des voitures et les premiers signes de la réappropriation de l’espace proche du Mont par les marées grâce à l’action des chasses du barrage sur le Couesnon.

5. BIBLIOgRAPHIEMinistère chargé de la Culture, ministère char-gé de l’Environnement, ministère chargé de l’Équipement (1995): « Projet de rétablissement du caractère maritime du Mont-Saint-Michel ». Séguin, J.-F. (1998): « Mont-Saint-Michel – La recon-quête d’un site », Le cherche midi éditeur.Migniot, C. (1998): « Rétablissement du caractère maritime du Mont-Saint-Michel – Synthèse des connaissances hydro-sédimentaires de la baie ».

Mission Mont-Saint-Michel (1999): « Rétablir le car-

actère maritime du Mont-Saint-Michel: les solutions proposées – programme technique détaillé ».

Morelon, J.-P. (1999): « Un projet d’équilibre pour la reconquête d’un site exceptionnel: le Mont-Saint-Michel », Échos du conseil général des ponts et chaussées.

Verger, F. (2000): « Entre terre et mer: le Mont-Saint-Michel », Pour la Science (édition française de sci-entific american) n°274.

Caude, G. et L’Her, J. (2005): « Rétablissement du caractère maritime du Mont-Saint-Michel : mo-délisation et suivi environnemental », la Houille Blanche, n°3.

De Beaulaincourt, F.-X. et L’Her, J. (2007): « Le ré-tablissement du caractère maritime du Mont Saint-Michel – le comité de suivi scientifique des travaux hydrosédimentaires », Colloque SHF-AIP-CN-CETMEF ‘Grands Aménagements’, Paris.

Caude, G. (2008): « Le Mont-Saint-Michel retrouve son caractère maritime – Brève synthèse du projet de rétablissement », revue technique maritime et fluviale n°1 – CETMEF.

Desguée, R. (2012): « Le rétablissement du car-actère maritime du Mont-Saint-Michel », Colloque SHF-AIPCN-CETMEF ‘Grands Aménagements du-rables’, Paris.

Syndicat mixte Baie du Mont-Saint-Michel (1997): « Rétablissement du caractère maritime du Mont-Saint-Michel – retrouver le Mont-Saint-Michel dans sa vérité – Projet ».

Syndicat mixte Baie du Mont-Saint-Michel – Revue la baie n°1 (août 1997) à 31 (novembre 2012) et suppléments :

Dossier hydrosédimentaire:

- n°1 les études hydrosédimentaires: démarches et solutions (mars 2001),

- n°2 les suivis hydrosédimentaires: comprendre et adapter (juin 2010).

Dossier environnement:

- n°1 environnement et paysage: retrouver la na-ture profonde de la baie (octobre 2001),

- n°2 environnement et paysage: le programme de suivi (juin 2009).

Site Internet: http://www.projetmontsaintmichel.fr

Crédits photos/illustrations/schémas:

Thomas Jouanneau, Altibreizh, Daniel Fondimare et Nicolas Borel, photographies/Luc Weizmann Architecte, croquis et dessins/Catherine Claden, maquette/Aprim - Syndicat Mixte Baie du Mont-Saint-Michel, schémas.

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The restoring operation of the Mont-Saint-Michel’s maritime character, launched in 1995, aims to re-turn the surrounding of the Mont-Saint-Michel to the sea and the sand. Important hydro-sedimenta-ry studies have established a project that involves the construction of a new dam allowing penetra-tion of the tide in the Couesnon to ensure flushes with strengthened volumes. The work began in 2005 and is monitored by a scientific committee.

The dam on the Couesnon was completed in 2009. Its architecture integrates all dimensions of a site where nature, art and culture meet in excep-tional circumstances. Design principles aimed at integrating required hydraulic functionalities and the creating of a space for contemplation.

From the hydraulic point of view, the dam has eight valves operated by two hydraulic cylinders each. The rotations of the valves ensure the filling by overflow to reduce the insertion of sediments and the discharge by underflow to optimise the effect of flushing. The dam is also a space open to the public: the promenade deck and maritime ob-servation terrace are treated as a space for walk-ing and a liaison between the two banks of the Couesnon. The dam is about 140 m with 8 passes of 9 m of hydraulic width each and 2 fish ways. His first feature is to restore Couesnon sufficient power to erode bottom sediments near the Mount. The hydraulic efficiency of the filling and emptying de-pends on the flow contribution of the Couesnon river and on the sea level. The dam works in two directions, allowing, in the filling phase, to limit the sediment intrusion in the upstream of the dam: the water inputs are then realised by overflow. In con-trast, at the time of release of water, flows are by underflow, thereby creating a flushing current.

Upstream of the dam, facilities include cleaning and pruning of banks, as well as the cleaning of the bed of the Couesnon to create a storage vol-ume of 800,000 m3. In addition a water reserve capacity of 300,000 m3 is reconstituted in Moidrey cove across 36 acres of canals. Through this work, the Couesnon find a storage capacity of nearly 1.1 million m3.

Downstream of the dam the works focus on the realisation of a dividing rockfill from the dam to the foot of the Mount, to create two channels of Couesnon which ensure a good distribution of flushing. This development is complemented by hydraulic structures: the creation of two priming channels and deflector and protector rockfills. The work is carried out in a very constraint environment given the tidal flows of the Couesnon river and the management of the dam. One implemented technique consists in the disposal of sediments

directly into the Couesnon river during periods of water releases from the dam and during the ebb tide to receive a discharge to sea due to the ac-tion of the current.

SUMMARY

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L’opération de rétablissement du caractère mari-time du Mont-Saint-Michel lancée en 1995 vise à rendre à la marée et aux sables les abords du Mont-Saint-Michel. D’importantes études hydro-sédimentaires ont permis d’établir un projet qui prévoit la construction d’un nouveau barrage permettant la pénétration de la marée dans le Couesnon pour assurer des chasses avec des vol-umes renforcés. Les travaux ont débuté en 2005 et sont suivis par un comité scientifique.

Le barrage sur le Couesnon a été achevé en 2009, son architecture intègre toutes les dimensions d’un site où nature, technique et culture se rencontrent de façon exceptionnelle. Les principes de sa con-ception visent à intégrer les fonctionnalités hy-drauliques souhaitées et la création d’un espace de contemplation.

Du point de vue hydraulique, le barrage com-porte huit vannes actionnées par deux vérins hy-drauliques chacune. La rotation des vannes per-met d’assurer le remplissage par sur-verse pour limiter les apports de sédiments et la vidange par sous-verse pour optimiser l’effet des chasses. Le barrage est aussi un espace ouvert au public: le pont-promenade et le balcon maritime sont traités comme un espace de déambulation et de liaison entre les deux berges du Couesnon. Le barrage d’environ 140 m est équipé de 8 passes de 9 m de largeur hydraulique chacune et de 2 écluses à poissons. Sa fonctionnalité première est de redon-ner au Couesnon une force suffisante pour érod-er les fonds sédimentaires aux abords du rocher. L’efficacité hydraulique des remplissages et vid-anges, dépend du débit d’apport du Couesnon fluvial et du niveau de la mer. Le barrage fonc-tionne dans les 2 sens, permettant, en phase de remplissage, de limiter les apports de sédiments dans les parties amont de l’ouvrage : les entrées d’eau se font alors par sur-verse. A l’opposé, au moment des lâchers d’eau, les écoulements se font par sous-verse, permettant ainsi de créer un courant de chasse.

En amont du barrage, les aménagements com-prennent le nettoyage et l’élagage des berges, ainsi que le curage du fond du lit du Couesnon pour obtenir un volume de stockage de 800.000 m3. En complément une réserve en eau d’une ca-pacité de 300.000 m3 est reconstituée dans l’anse de Moidrey à travers 36 ha de canaux. Grâce à ces travaux, le Couesnon retrouvera une capaci-té de stockage de près d’1,1 million de m3.

A l’aval du barrage les travaux d’aménagement portent sur la réalisation d’un seuil de partage depuis le barrage jusqu’au pied du Mont, afin de créer deux chenaux du Couesnon qui garantiront

une bonne répartition des chasses. Cet aménage-ment est complété par des ouvrages hydrauliques : la création de deux amorces de chenaux et d’épis écarteurs et protecteurs. Les travaux sont réalisés dans un environnement très contraignant compte tenu des marées, des débits du Couesnon et de la gestion du barrage. Une technique mise en œuvre consiste à relâcher les sédiments direct-ement dans le lit du fleuve Couesnon, pendant les périodes de lâchers d’eau du barrage et pendant la marée descendante afin de bénéficier d’une évacuation vers le large grâce à l’action du cou-rant.

RESUME

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Der Wiederherstellungsprozess des maritimen Charakters des Mont-Saint-Michel, der im Jahr 1995 begonnen wurde, hat eine Meerwasser- und Sandumgebung des Mont-Saint-Michel zum Ziel. Bedeutende hydro-sedimentäre Studien dienten als Grundstein eines Projekts, das den Bau eines neuen Damms beinhaltet, der das Eindringen der Tide in den Couesnon erlaubt und so das Aus-schwemmen in größerem Umfang sicherstellt. Die Arbeiten begannen im Jahr 2005 und werden von einem wissenschaftlichen Komitee begleitet.

Der Damm am Couesnon wurde im Jahr 2009 fer-tig gestellt, seine Architektur verflechtet sämtliche Dimensionen an einem Schauplatz, an dem Natur, Kunst und Kultur in außergewöhnlicher Weise auf-einandertreffen. Die Gestaltungsgrundsätze hat-ten zum Ziel, die erforderlichen hydraulischen Funktionalitäten mit dem Schaffen eines Ortes der Kontemplation zu verbinden.

Aus hydraulischer Sicht hat der Damm acht Du-rch-lassventile, die jeweils von zwei hydraulischen Zylindern betrieben werden. Die Rotation der Ven-tile sorgt beim oberstromigen Überlaufen für einen reduzierten Sedimenteintrag und regelt zugleich das Rücklaufgeschehen, um den Spüleffekt zu optimieren. Der Damm ist auch ein für die Öffent-lichkeit geöffneter Raum: Das Promenadendeck und die Seeterrasse sind begehbar und bilden so eine Verbindung zwischen den beiden Ufern des Couesnon. Der Damm ist ca. 140 m lang, besitzt acht Durchlässe mit jeweils 9 m hydraulischer Brei-te und verfügt über zwei Fischpässe. Seine Haupt-aufgabe ist es, dem Couesnon genügend Kraft zu liefern, um die Bodensedimente in der Nähe des Berges Saint-Michel zu erodieren. Die hydraulische Effizienz des Füll- und Entleersystems hängt von dem Zufluss des Couesnon und zugleich von der Höhe des Meeresspiegels ab. Der Damm funktioniert in zwei Richtungen, wodurch es möglich ist, während der Füllphase den Sedimenteintrag oberstrom des Damms zu begrenzen: Die Wassereinträge werden hierbei durch Überströmung erzielt. Im Gegensatz dazu wird bei ablaufendem Wasser durch Unter-strömung eine Spülströmung erzeugt.

Oberstrom des Damms gibt es Vorrichtungen zum Reinigen und Freischneiden der Böschung-en, ebenso wie zur Reinigung des Bettes des Couesnon, was zu einem Speichervolumen von 800.000 m³ führt. Zusätzlich wird in der Moidrey-Bucht eine Wasser-Reservekapazität von 300.000 m³ auf einer Fläche von über 36 Acre (1 Acre ~ 4047 m²) des Kanals wiederhergestellt. Dadurch beträgt die Speicherkapazität des Couesnon fast 1,1 Mio. m³.

Unterstrom des Damms konzentrieren sich die Ar-

beiten auf die Errichtung einer trennenden Stein-schüttung vom Damm zum Fuße des Berges, um zwei Kanäle für den Couesnon zu bauen, die eine günstige Verteilung der Spülströmung gewährlei-sten sollen. Dieser Ausbau wird durch weitere hydraulisch wirksame Elemente vervollständigt: Bau von zwei Grundkanälen sowie abweisende und schützende Steinschüttungen. Die Arbe-iten werden in einer eng begrenzten Umgebung durchgeführt, bedingt durch die Tideströmungen im Couesnon und den Betrieb des Dammes. Eine implementierte Verfahrenstechnik besteht in der Ablagerung von Sedimenten direkt im Couesnon in Zeiten, in denen das Wasser aus dem Damm strömt sowie während Ebbe, um bedingt durch die Strömung einen Abfluss zum Meer zu erreichen.

ZUSAMMENFASSUNg

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KEY WORDS: Seine estuary, compensatory mea-sures, scientifi c follow-up, morphology, biological resources

MOTS-CLES: estuaire de la Seine, mesures com-pensatoires, suivis scientifi ques, morphologie, res-sources biologiques

1. INTRODUCTION

With more than € 50 million dedicated to environ-mental measures, Port 2000, an extension to the port of Le Havre constructed between 2001 and 2005, is part of a genuine sustainable development policy for the Seine estuary carried out in close co-operation with the stakeholders concerned. Half of that budget has been allocated to an exten-sive programme of rehabilitation of the mud fl ats, an environment conducive to development of organisms that form a vital link in the food chain for many species. Other measures include the cre-ation of new rest areas for birds, the aim being to

promote biodiversity in the Seine estuary and to support the management of nature areas (Nature Reserve and specifi c ‘Espace Préservé’ (Preserved area immediately southeast of Port 2000). To as-sess the impact of these environmental measures, a large-scale scientifi c monitoring programme has been implemented since 2000 in conjunction with the Scientifi c Council of the Seine Estuary.

After describing the main infrastructure of Port 2000 and the associated environmental measures, this paper presents the various scientifi c programmes and discusses the main methodological lessons learnt in the conclusion.

2. PORT 2000 AND THE MAIN ENVIRONMENTAL MEASURES2.1. Port Infrastructure

The work exclusively relating to the port (Fig. 1 on the next page) mainly comprises a breakwater some 5.5 km long extending into the estuary of the Seine to shelter 4.2 linear km of quays. Access to the quays is via a navigation channel approxi-mately 7 km long dredged in the riverbed which was previously located at – 3m LHSL (Le Havre Sea Level), down to a depth of – 16 m LHSL over a width varying from 300 to 600 m. It joins the ship-ping channel about 1km from the entrance chan-nel to the port of Le Havre. Some 60 million m3 of material have been dredged half of which being reused in the civil engineering works (reclamation and breakwaters), the remainder being deposited in the sea off Octeville outside the estuary.

MONITORING Of PORT 2000 ENVIRONMENTAL MEASURES

LE SUIVI DES MESURES ENVIRONNEMENTALES DE PORT 2000

PASCAL gALICHON

Grand Port Maritime du HavreTerre-Plein de La Barre BP 141376067 Le Havre CedexFrance

Tel: +33 (0)2 32 74 70 30E-mail: pascal.galichon@havre-port.fr

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Since the Port 2000 facilities reduce the width of the estuary in its downstream section, an increase in currents was expected, resulting in the erosion of the Northern trench of the Seine estuary lo-cated directly south of Port 2000. To support this change in the bottom and minimise its impact, support dredging to help recalibrate the Northern trench was carried out. Sedimentological studies conducted by SOGREAH showed the dredging work was of interest both in controlling the sedi-mentological changes in the Northern trench and the access channel to the Port of Rouen, but also of ecological interest as a means of preserving the mudflats and the species that live within them, lo-cated at the foot of the Pont de Normandie (Nor-mandy Bridge).

Modelling was used for the preliminary sizing of the volumes, locations and phasing of the support dredging work. Regular monitoring of the bottom during construction work allowed the dredging to be adapted according to the morphologi-cal changes observed (3.5 million m3 have been dredged).

Fig. 1: Location of the various facilities

2.2. Environmental Work

The environmental interest of the Seine estuary and the findings concerning its past changes led the Grand Port Maritime du Havre to imple-ment, as part of the Port 2000 project, a major pro-gramme of environmental measures designed to preserve and develop the environmental features which were declining, mainly due to the reduc-tion in the surface area of the interdidal mudflats. These measures included development work.

2.2.1. ‘The Dune Bird Resting Area’: An Area of Peace and Quiet for Water Birds

Defined in relation with the regional environment directorate (DREAL) and the organisation in charge of the nature reserve (Maison de l’Estuaire), the de-velopment work was carried out during the winter of 2001-2002, the aim being to provide a function-al replacement for the site (which now no longer exists) where birds concentrated before construc-

tion work began on Port 2000. This first environmen-tal measure to be implemented, the construction of a bird resting area near to the dune zone, was completed in February 2002 before any work took place on the site requiring compensation. Cover-ing a surface area of some 30 ha, the land was remodelled to encourage usage of the site by wa-ter birds of the estuary (ducks and other species feeding on the mud flats at low tide) needing rest areas at high tide.

Ornithological monitoring by the Avifauna Obser-vatory of the Seine Estuary resulted in additional developments to increase the site’s attractiveness. For example, an area was regraded to promote the nesting of avocets, and a gate to manage the water levels inside the resting area were put in operation in 2005. The most recent monitoring has indicated a gradual increase in site occupancy, which is now promising, in particular through the effective management of water levels by the Mai-son de l’Estuaire. In 2010, nesting by 10 different species was observed, including 50 pairs of avo-cets.

2.2.2. The Bird Resting Island in the Seine

Designed to accommodate seabirds and diver-sify the sites for the different species of seabirds to nest and rest, an island covering five contiguous hectares at low tide is located in the southern part of the estuary (opposite Villerville). Its construction was completed in April 2005. The site, which is one of its kind, is 320 metres long and 200 metres wide. Its main characteristics (shape and land level) were defined in very close cooperation between the regional environment directorates (DREAL) for Upper and Lower Normandy, the Normandy Ornithological Group (GONm) and the port engi-neers.

In accordance with the decree creating the Na-ture Reserve inside which it was built, except for the officers of the Maison de l’Estuaire who carry out the scientific monitoring of its use by birds and the eventual introduction of other species of flora and fauna, all forms of human presence are pro-hibited in order to preserve the tranquillity of the site. A video camera has been installed to improve the quality of follow-up without disturbing the birds on the island.

The first bird counts that were made immediately showed the merits of the design of the island with more than a thousand birds of more than twenty different species regularly nesting and resting on it. Since then, nearly sixty species of birds have been observed, at least three of which breed on the island in 2010 (Common Shelducks, Great Black-Backed Gulls and Mallards). Botanical monitoring has shown the presence of about 70 plant species including a growing number of heritage species.

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2.2.3.RestorationoftheInterdidalMudflats,aMajor Environmental Component of Port 2000

During the consultations held throughout the de-velopment phase of the Port 2000 project, it quick-ly became apparent that the major environmen-tal challenge of the Seine estuary concerned the mudflats, whose surface area was very significantly decreasing (by some 25 ha/year). It was therefore agreed that the main environmental measure of Port 2000 should focus on a programme to reha-bilitate the intertidal estuary mud flats, the aim be-ing to impede the progression of grassy marshes and to create new mud flats.

The rehabilitation work on the mud flats was speci-fied further to the various studies that were carried out.

Fig. 2 locates the various works, namely:

• a curved seawall oriented in the southwest/northeast direction connected to the north low-crested Seine breakwater opposite Honfleur

• a breach in the breakwater 550 m long, 2 km upstream of the Pont de Normandie

• raising the current breach• the digging of a channel between the current

breach and the future breach • raising the North low-crested breakwater by

1 metre between the current breach and the head of the seawall described above

• the installation of a layer of pebbles and rocks to protect the bridge piers of the viaduct of the Pont de Normandie

Initiated during the summer of 2003, the rehabilita-

tion work on the mud flats was completed in the summer of 2005. Several phases of implementa-tion were deemed necessary in order to let nature take its course and to check step-by-step the ac-curacy of the modelling carried out during the de-sign phase.

Scientific monitoring of the rehabilitation pro-gramme of the mud flats of the Seine estuary made between 2005 and 2010 highlighted several findings on the bio-hydro-sedimentary situation of the mudflats, namely:

• The progression of the grassy marshes had ef-fectively been halted

• Mud flats were effectively developing over more than 100 ha downstream of the facilities (along the low northern breakwater and south of the dune bird sanctuary)

• The ‘Banc de la passe’ east of the curved scan-wall has risen in height. It mainly consists of sand, recently covered by a mud layer progressing from west to east, which is encouraging,

• On the other hand, a significant input of sedi-ment is occurring in the environmental channel dredged upstream of the Pont de Normandie. This development, which had not been envis-aged when designing the facilities, is continuing to be monitored in close conjunction with the Scientific Council of the Seine Estuary.

In addition, scientific monitoring of the biological elements can be used to highlight the relation-ships between the physical environments and living habitats observed. Overall, in terms of the species found, the northern part of the estuary is becoming increasingly marine in nature, although

Fig. 2-3: Location and layout of the development

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it is not possible to determine whether this is due to the impact of the development work or to the low flow rates of the river Seine since the end of the work.

2.2.4. Environmentally Oriented Beach

Since the construction of Port 2000 removed a beach on which a protected species grew (‘Crambe maritima’), it was necessary to recre-ate a similar environment in order to re-introduce the species. The environmentally oriented beach marks the eastern tip of the backfilled area south of the Charles Laroche dyke. Constructed in 2003 under the protection of the breakwaters of Port 2000, it is a little over 500 m long and its initial cross section has beach slopes similar to those observed in the natural environment. Experimental settle-ment took place. Monitoring carried out after the first attempts to implant ‘Crambe maritima’ by the Bailleul National Botanical Conservatory showed that the instability of the beach was such that the deliberate settlement of ‘Crambe maritima’ was not sustainable. The operation will be renewed once the beach has become more stabilised. In addition, it is worth noting that instances of natu-ral colonisation by ‘Crambe maritima’ have been found on the outer beach of Port 2000, which was built at the head of the Northern breakwater for hydraulic purposes (to decrease the number of overflows).

2.2.5. The Creation and Ecological Manage-ment of a Preserved Area of 70 Hectares

During the preliminary studies for Port 2000, vari-ous rare or protected species were identified in a natural area of some about 70 hectares that the Grand Port Maritime du Havre decided to pre-serve. It included plants (several orchids, marsh peas and dune grass), amphibians (frogs, newts, toads) and birds (nesting, migrating and winter-ing species). This area – now called the ‘Preserved Area’ – was originally intended for logistics facili-ties to the Southeast of Port 2000.

The main measures for the management and sci-entific monitoring of this Preserved Area were en-trusted by a convention to the Maison de l’Estuaire and the Bailleul National Botanical Conservatory as part of the management plan for the Preserved Area. The plan includes various restoration and management operations of the more interesting habitats and scientific monitoring of the protected species. In particular, since 2001, the botanists at the Conservatory have been entrusted with man-aging sectors in which the Liparis Loesel orchid grows (a plant protected at the European level).

An environmental management plan was drafted for the 2004/2011 period with the help of the Na-ture Reserve, the Bailleul National Botanical Con-servatory and the Regional Directorate for the En-

vironment. A new management plan developed on the basis of scientific surveys carried out dur-ing the first management plan has been adopted with the same partners for the 2012-2016 period.

3. THE gENERAL ORgANISATION OF SCIENTIFIC MONITORINg3.1.GeneralMonitoringSpecifications

With the help of the scientists working on the Seine estuary, an extensive programme of sci-entific monitoring operations in areas likely to be affected by Port 2000 was developed. In order to be consistent with the various already existing scientific programmes on the Seine Estuary, main-ly the Seine-Aval programme, the specifications for the monitoring operations were presented by the Grand Port Maritime du Havre and approved by the Scientific Council of the Seine Estuary. This council consists of a dozen scientists covering various areas of major interest to the Seine estu-ary (sedimentology, water quality, biological re-sources, etc.). It also helps interpret the results.

3.2. Implementation of Monitoring

Apart from monitoring the change in the bottom carried out by the ports of Le Havre and Rouen, both of which have the means and skills to ac-quire this type of data (the interpretation being entrusted to outside consultants), scientific moni-toring is entrusted after open and competitive calls for proposals (except in cases of unique expertise), to the appropriate laboratories or authorities. Funding is overwhelmingly provided by the Grand Port Maritime du Havre except in certain cases where pooling with other partners proved relevant.

3.3. Dissemination of Results

The scientific monitoring results in reports and regular presentations to the Scientific Council of the Seine Estuary, which helps interpret the re-sults and ensures consistency with other scientific programmes existing on the estuary. In addition, depending on the topics, the results may be ex-changed with other more specialised bodies (re-search teams, etc.).

To help the dissemination of knowledge and im-prove the sharing of information on changes in the estuary, the acquired data are also made available to the all the scientific community and more particularly that associated with the Seine-Aval scientific programme through the Seine-Aval Public Interest Group which unites scientific re-search across the Seine estuary and the eastern Bay of the Seine.

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4. THE SCIENTIFIC MONITORINg PROgRAMME4.1. The Different Themes and general Methodologies

The scientific monitoring of Port 2000 focuses on:

- the changes in the beds of the estuary from both the morphological and granulometric points of view, because the types of sediment influence the types of living organisms that live in them,

- the biological resources of the estuary with specific respect to the benthic and supraben-thic species, the fish and shellfish and finally the birds,

- the protected species on land (flora and fauna) that have been subject to special conservation measures.

4.1.1. Monitoring Changes in the Beds of the Estuary

Monitoring the changes in the beds comprise first of all the morphological changes, but also the changes in the nature of the sediments. Monitor-ing is mainly carried out by the Grands Ports Mari-time of Rouen and Le Havre, both of which have the technical and human resources needed to conduct the monitoring operations and analyse their results in conjunction with specialised con-sulting firms. Throughout the construction period (January 2002 - March 2005), surveys of the North-ern trench were carried out every two months and an overview of the readings for the entire estuary is produced once a year by the Grand Port Mari-time of Rouen. In conjunction with the bathymetric readings for the Northern trench of the Seine estuary, sediment samples are taken twice a year to clarify the sedi-mentary dynamics observed.

Because of the difficulty of access to certain ar-eas (the high intertidal mudflats) and the develop-ment of airborne laser techniques (LIDAR), bathy-metric surveys are completed by surveys using this technology. Surveys of this type were carried out in 2001, 2004, 2006, 2008, 2010 and annually since. It should be noted that these quantitative data are supplemented annually by high-resolution pho-tographs of sedimentary structures that enable a spatial approach. This work is done by Mr A. Cuvil-liez of the University of Le Havre in continuity to the work for his PhD thesis.

During the construction work on Port 2000, ob-servations were regularly detailed in a technical committee chaired by the Director of the Centre for Maritime and Fluvial Studies (CETMEF). It was this committee which checked that the chang-

es observed were consistent or inconsistent with those forecasted by the various models and de-cided whether adaptations in the phasing of the works and support dredging were needed in or-der to minimise the impact of construction work on the dynamics of the estuary and particularly on the mudflats and the navigational channel of the Port of Rouen. The Scientific Council of the Seine Estuary was also informed of the observations and measures taken.

Since the end of the construction work and after a call for proposals, the bed development data ac-quired are provided to ARTELIA which carries out an annual analysis that is presented to the Scien-tific and Technical Council of the Seine estuary. All the data acquired and their interpretation are of particular use in the production of a digital 3-D hy-drosedimentary model of the Seine estuary which was entrusted to ARTELIA after a European call for proposals, its purpose being on the one hand to understand the changes better and secondly to study what additional developments might be considered in order to improve the effectiveness of the developments made to date.

4.1.2. Monitoring the Biological Resources of the Estuary

Preceded by overviews of existing knowledge in 1994-1995, scientific monitoring of the biological resources in the estuary began before the con-struction work in order to have an initial situation report with which to establish a reliable baseline on the one hand and on the otherhand a diag-nosis as relevant as possible on the impacts of the project.

Benthic species

The monitoring of benthic species involves three components: the intertidal benthos, the subtidal benthos and the suprabenthos.

Monitoring of the intertidal benthos is performed in conjunction with the Maison de l’Estuaire, which is in charge of managing the Nature Reserve. As part of Port 2000, since 2002, a campaign has been carried out in September each year on eight radial sectors located on either side of the Pont de Normandie.

Monitoring of the subtidal benthos was entrusted to the Normandy Coastline Monitoring Unit, two campaigns per year (in September and March) having been conducted since 2002, after an initial situation report done in 2001.

Monitoring of the suprabenthos was initially car-ried out by the laboratory of the Wimereux Ma-rine Station and Caen University. Initiated in 2001, two campaigns per year took place until 2006, but given the absence of any significant changes

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in the suprabenthic species, the following cam-paigns took place in 2011-2012.

The analysis of the changes in benthic species confirms the increasingly maritime nature of the northern trench of the Seine estuary.

Fishery Resources

Given the major impact that Port 2000 might have had on commercial fishing activities, the first an-nual monitoring of fish nurseries was entrusted to IFREMER in 1995 long before any work in the Es-tuary. After consultations with professional fish-ermen, monitoring of the fishery resources was increased from 2000 onwards. The Normandy Coastline Monitoring Unit has carried out between 6 and 8 campaigns every year since June 2000. Each campaign involves 32 research trawls cover-ing the whole of the estuary. It is supplemented by specific fisheries in the run-off channels that con-stitute related intertidal habitats of interest to cer-tain species of the juvenile fish (sea bass, flounder, smelt, etc.).

The variations in fish populations observed differ according to the species concerned and range within the classic inter-annual oscillations observed on other sites that have not been subject to con-struction work.

Over and above the evaluation of the impact of construction work on Port 2000, these monitoring operations have also improved knowledge on the one hand of shrimp cycles in the Seine estuary, and on the other that of the role of all the small rivers in the estuary for certain species of juvenile fish such as bass. In addition, by starting to have a long chronological series of observations (of more than ten years) it is possible to highlight correla-tions with multi-annual kinetic phenomena.

Faced with the need for as accurate an estimation as possible of the impact of Port 2000 on profes-sional fishing, in addition to the scientific monitor-ing of the resources mentioned above, monitoring systems on economic fishing issues have also been implemented. For example, in close conjunction with local fishing committees in Le Havre and Hon-fleur-Courseulles and under the aegis of the Direc-torate-General for Maritime Affairs and Fisheries, a system for collecting catch data was introduced in 2000. In view of its relevance especially for pro-fessional fishermen, the system originally intended to last the same period as the construction work, i.e. until 2005, was initially extended until 2011 and then again until 2015.

Birdlife in the Estuary

Sparse data on birdlife in the estuary existed prior to 1995, and so the Port of Le Havre Authority en-trusted the Andrews firm of consultants in 1995 with

an inventory, carried out with the help of the Nor-mandy Ornithological Group.

Since 1999, data are routinely acquired by the bird observatory set up by the Maison de l’Estuaire in conjunction with the Boucles de la Seine Nor-mandy Nature Park. The operations are partially financed by Port 2000 funding reserved for scientif-ic monitoring. They include systematic monitoring of the most interesting species, mainly based on monthly readings for the entire Seine estuary with more detailed observations on the facilities pro-vided for birdlife (dune bird resting area and the resting island). The data thus acquired also serve as input for national statistics on the observation of birdlife.

4.1.3. Monitoring of Protected Species on Land

An inventory of the species of flora and fauna in the area concerned by the future Port 2000 termi-nals was completed in 2001. Noteworthy results in-cluded the presence of protected species of am-phibians (Natterjack toad and Common parsley frog) and plants (Liparis loeselii, Oxtongue Broom-rape, seakale – ‘Crambe maritima’).

For the amphibians, before any work began, it was decided and authorised to capture and then re-lease the amphibians on sites safe from any devel-opment. Scientific monitoring of the success of the operations was carried out for three years by the LBPA of the University of Savoie, making it possible to assess the development of the species trans-ferred and to acquire further knowledge about the behaviour of these animals. The monitoring showed that on two of the three sites selected, the transferred individuals were still present. Since this initial monitoring, other operations were undertak-en over the period 2009-2011 by Fauna Consult to have a vision of the development of the species still present in large numbers in the port area and that their state of health is good.

For plant species, the main management and scientific monitoring measures involved the Pre-served Area except for the ‘Crambe maritima’, which was replanted on the ecological beach. Implementation of the management action plans for the Preserved Area was entrusted to the Maison de l’Estuaire and to the Bailleul National Botanical Conservatory. Within that framework, since 2001, the botanists at the Conservatory have been en-trusted with managing sectors in which the Liparis Loesel orchid grows (a plant protected at the Eu-ropean level). For example, in the autumn of 2004, they began experimental digging in these sectors in order to promote soil moisture, a crucial factor for the survival of this wetland plant. At the end of 2003, the same botanists planted a protected species, Oxtongue Broomrape, in the Preserved area, to ensure its preservation outside the areas

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affected by Port 2000. Annual monitoring is un-dertaken to examine the dynamics of the species and guide management actions.

5. CONCLUSION5.1.ScientificMonitoringasaMeansforDialogue and Consultation

The quality of the scientific monitoring carried out before the start of the construction work on Port 2000 was necessary to have a satisfactory situa-tion report integrating the multi-annual variations of the various parameters monitored. Recognition of the quality of the initial data is important, first in order to correctly understand the impact of Port 2000 and secondly, to facilitate the dialogue be-tween the contracting authority and the various stakeholders involved, because only quality data enables consultation based on mutually recog-nised objective facts rather than on more or less properly-substantiated assumptions. For that qual-ity to be recognised, the methodologies used re-quire validation by parties other than the project’s proponents.

5.2.ScientificMonitoringasaBasisforAdaptive Management

Carrying out port construction work and environ-mental projects at the same time was one of the major technical difficulties in Port 2000, since all of them had to be studied, selected and implement-ed in order to minimise the impact of port activities on the estuarine environment. The scientific moni-toring operations carried out during construction work and more particularly those concerning the changes in the riverbeds have made a significant contribution to the optimisation of project man-agement. Similarly, the scientific monitoring op-erations carried out to assess the effectiveness of the environmental work are essential in order to develop adaptive management strategies, be-cause ecological engineering is not as exact a science as port engineering and it should always be possible to adapt the facilities on the basis of the observations performed.

5.3.ScientificMonitoringasaSustainablePartnership Approach

The scientific monitoring associated with Port 2000 was originally scheduled to last a maximum of 10 years. Because of the estuarine dynamics, the multi-annual variations observed and the difficulty in interpreting certain evolutions, it was consid-ered necessary to maintain the monitoring longer than the initial ten-year period. In addition, the data acquired during the monitoring of the facili-ties associated with Port 2000 proved to be useful to other stakeholders, whether scientific or not. In

addition, it was considered absolutely vital both from a purely scientific point of view and from the financial point of view, on the one hand that the scheduling of scientific monitoring operations be conducted in line with other scientific monitoring programmes existing in the same region, and on the other hand, that they have the benefit of a multidisciplinary scientific structure capable of as-sessing and adapting them in accordance with the results observed.

For these various reasons, this type of scientific monitoring of the impacts of facilities must be set up from the start as a partnership approach in or-der to share the costs and exchange the knowl-edge acquired on a sustainable long-term basis. With this in mind, the provision of data acquired must be based on partnerships with organisations such as Scientific Public Interest Groups (the Seine Aval public interest group in our case) or a Region-al Biodiversity Observatory.

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Port 2000, which is a large-scale extension of the port of Le Havre with 4.2 km of quay dedicated to container traffic, included significant environ-mental measures (€ 50 million). With input from the scientists working on the river Seine estuary, a vast programme was drawn up of scientific surveys in the areas affected by Port 2000 and its environ-mental measures. Focusing on consistency and knowledge sharing, the programmes were de-fined in conjunction with the Scientific Council of the Seine Estuary, which also helps interpret the results. The main topics followed up include the

hydro-sedimentary dynamics of the Seine estuary, its biological resources and protected species.

The scientific surveys were seen to be essential as a means of constituting a solid basis for coopera-tion with the various stakeholders in the Estuary, and needed in order to adjust the facilities with re-spect to the results obtained and the requisite ob-jectives. Initially scheduled for a ten-year period, it has been decided to extend the programme and develop partnerships with scientific groups in order to share and further the knowledge acquired.

SUMMARY

Port 2000, importante extension du port du Havre (4,2 km de quai dédiés au trafic conteneur) a inté-gré des mesures environnementales conséquentes (€ 50 millions). Avec l’aide de scientifiques travail-lant sur l’estuaire de la Seine, un important pro-gramme de suivis scientifiques dans les domaines sur lesquels Port 2000 et ses mesures environnemen-tales ont des impacts a été élaboré. Dans un souci de cohérence et de partage des connaissances, la définition de ces programmes a été faite en lien avec le Conseil Scientifique de l’Estuaire de la Seine qui concourt aussi à l’interprétation des résultats. Les principales thématiques suivies sont: la dynamique hydro-sédimentaire de l’estuaire de

la Seine, les ressources biologiques estuariennes et des espèces protégées terrestres.

Les suivis scientifiques sont apparus essentiels pour constituer des bases solides de concertation avec les différents acteurs de l’Estuaire et nécessaires pour pouvoir adapter les aménagements faits au regard des résultats observés et des objectifs re-cherchés. Initialement programmé sur 10 ans, il est apparu utile d’aller au-delà de cette durée et de développer les partenariats avec les groupe-ments scientifiques pour mutualiser et consolider les différentes connaissances acquises.

RESUME

Bei dem Projekt „Hafen 2000“ handelt es sich um eine großräumige Erweiterung des Hafens von Le Havre mit einem 4,2 km langen Kai für Contai-nerschiffe, das zudem bedeutende Umweltschutz-maßnahmen (50 Mio. €) beinhaltet. Mit Hilfe von Wissenschaftlern, die im Mündungsgebiet der Seine arbeiten, wurden umfangreiche wissen-schaftliche Studien sowie Umweltschutzmaßnah-men für die betroffenen Gebiete erarbeitet. Mit Schwerpunkt auf Konsistenz und Wissensaustausch wurden die Programme zusammen mit dem Wis-senschaftsrat für die Seine-Mündung (Scientific Council of the Seine Estuary) definiert, der auch dabei helfen wird, die Ergebnisse zu interpretieren. Die Hauptthemen, die verfolgt werden, sind die

Hydro-Morpho-Dynamik im Seine-Ästuar, dessen biologischen Ressourcen und die dort geschütz-ten Arten. Die wissenschaftliche Begutachtung wurde für notwendig erachtet, um eine solide Basis für die Kooperation mit den verschiedenen Akteuren im Seine-Ästuar aufzubauen und um die Raumpla-nung an die gewonnenen Ergebnisse und die gesetzten Ziele anzupassen. Es wurde beschlos-sen, das ursprünglich für 10 Jahre vorgesehene Programm auszudehnen und Partnerschaften mit wissenschaftlichen Gruppen aufzubauen, um das erlangte Wissen zu teilen und zu erweitern.

ZUSAMMENFASSUNg

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KEY WORDS: ports, waterways, strategy, infra-structures, services

MOTS-CLES: ports, voies navigables, stratégie, in-frastructures, services

1. LA SITUATION DU TRANS-PORT MARITIME ET FLUVIAL

EN FRANCE ET EN EUROPE Depuis un demi-siècle environ, le volume du trafi c maritime mondial n’a cessé de croître. On observe sur les dix dernières années un taux de progression annuel en volume d’environ 4 %. Le développe-ment des gains de capacité unitaire par navire a favorisé la progression constante du tonnage des marchandises transportées dans un contexte de globalisation des échanges.

L’AMBITION D’UNE STRATéGIE NATIONALE POUR LES TRANSPORTS MARITIMES ET fLUVIAUx EN fRANCE

RéPONDANT AUx ENJEUx DE LA TRANSITION éCOLOGIqUE

ThE AMBITION fOR A MARITIME AND INLAND wATERwAY TRANSPORT STRATEGY IN fRANCE AS AN ANSwER TO ThE ChALLENGE Of ECOLOGICAL TRANSITION

JéRÔME MEYER

Chef du bureau de l’analyse économique des transports fl uviaux et maritimes et des ports

Tél.: +33 1 40 81 73 43Fax: +33 1 40 81 72 90 E-mail: jerome-a.meyer@developpement-durable.gouv.fr

THIERRY LAgADEC

Chargé d’études économiques, bureau de l’analyse économique des transports fl uviaux et maritimes et des ports

Tél.: +33 1 40 81 84 72, +33 1 40 81 72 90, E-mail: thierry.lagadec@developpement-durable.gouv.fr

DIDIER BEAURAIN

Chef du bureau du transport fl uvial

Tél.: +33 1 40 81 13 22, +33 1 40 81 72 90, E-mail: didier.beaurain@developpement-durable.gouv.fr

JéRÔME MEYER

Chef du bureau de l’analyse économique des transports fl uviaux et maritimes et des ports

Tél.: +33 1 40 81 73 43Fax: +33 1 40 81 72 90 E-mail: developpement-durable.gouv.frdeveloppement-durable.gouv.fr

THIERRY LAgADEC

Chargé d’études économiques, bureau de l’analyse économique des transports fl uviaux et maritimes et des ports

Tél.: +33 1 40 81 84 72, +33 1 40 81 72 90, E-mail: developpement-durable.gouv.frdeveloppement-durable.gouv.fr

THIERRY LAgADEC

KEY WORDS: ports, waterways, strategy, infra-

DIDIER BEAURAIN

Chef du bureau du transport fl uvial

Tél.: +33 1 40 81 13 22, +33 1 40 81 72 90, E-mail: developpement-durable.gouv.frdeveloppement-durable.gouv.fr

DIDIER BEAURAIN

HéLÈNE FREYTOS

Chargée d’études « Développement durable du transport fl uvial », bureau du transport fl uvial,

Tél.: +33 1 40 81 22 36, Fax: +33 1 40 81 72 90, E-mail: helene.freytos@developpement-durable.gouv.fr

BENJAMIN BOYER

Chargé d’études « Réglementation technique du transport fl uvial », bureau du transport fl uvial

Tél.: +33 1 40 81 72 65, +33 1 40, Fax: 81 72 90, E-mail: benjamin.boyer@developpement-durable.gouv.fr

gAUTIER HOUEL

Chargé de mission « Réforme des voies navigables », bureau des voies navigables,

Tél.: +33 1 40 81 87 73, Fax: +33 1 40 81 16 61,E-mail: gautier.houel@developpement-durable.gouv.fr

YOANN LA CORTE

Adjoint au chef du bureaudes voies navigables

Tél.: +33 1 40 81 13 42Fax: +33 1 40 81 16 61, E-mail: yoann.la-corte@developpement-durable.gouv.fr

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Le ‘rail du Nord’ européen est la deuxième fa-çade maritime mondiale. De la mer du Nord à l’océan Atlantique en passant par la Manche, il s’agit de la principale interface maritime de l’Europe. Il génère plus de 600 millions de tonnes de trafi c. Dominé par Rotterdam, le principal port européen, Anvers et Hambourg, c’est la véritable porte d’entrée de l’Europe.

La France était en 2010 la 6ème puissance mon-diale exportatrice de marchandises et la 2ème

exportatrice mondiale de produits agricoles1. La France compte aujourd’hui une quarantaine de ports de commerce sur son territoire. Ces espaces voués au transit de marchandises et de passag-ers concentrent des activités (industrie, logistique, services) en constante relation avec le monde extérieur. Avec près de 360 millions de tonnes de fret dont environ 50 % de vracs liquides et 13 % de march-andises conteneurisées traitées chaque année dans les ports de commerce maritimes français, le secteur portuaire français représente 5 % du trafi c mondial et 10 % du trafi c européen. La France compte deux ports parmi les 50 plus grands ports mondiaux. Marseille et Le Havre sont placés aux 5ème et 6ème rangs européens en volume total de marchandises traitées. Marseille est le 3ème port pétrolier au monde, Le Havre est le 10ème port de conteneurs en Europe et le port de Rouen le 1er port céréalier d’Europe.

Fig. 1: Transport de granulats par voie fl uviale sur la Seine (© Laurent Mignaux/METL-MEDDE)

De son côté, le transport fl uvial ne représente que 6 % en tonnes kilomètres des transports ter-restres en Europe. L’activité du transport fl uvial est concentrée sur le bassin du Rhin qui con-stitue une infrastructure naturelle performante à l’embouchure duquel se trouve Rotterdam, pre-mier port maritime européen qui dessert de vastes territoires industriels (la Ruhr, …). L’Allemagne et les Pays-Bas réunis représentent près de 75 % de l’ensemble du transport fl uvial européen. Si l’on ajoute le transport fl uvial belge et français, le total

représente alors près de 90 % de l’ensemble du transport fl uvial européen. En France, le trafi c fl u-vial est aujourd’hui concentré sur les voies naviga-bles à grand gabarit. Le trafi c fl uvial sur le réseau Freycinet est relativement faible et très concentré en certains points du réseau. En tonnes transpor-tées, le bassin de la Seine génère plus de la moitié du trafi c fl uvial français. Le bassin du Rhône et de la Saône se place en deuxième position, suivi de la partie française du bassin rhénan (Source: Voies navigables de France, 2011).

2. LE DEVELOPPEMENT DES INFRASTRUCTURES FACE AUX ENJEUX DU XXIème SIECLELes premiers ports français disposent d’infrastruc-tures de qualité et capables (tirant d’eau, longueur des quais, nombre de poste à quai) d’accueillir et traiter tous les types de navires, même les porte-conteneurs de toute dernière génération. Ils sont équipés d’outillages modernes régulièrement re-nouvelés permettant de garantir un taux de pro-ductivité au-dessus de la norme internationale.

La France dispose également d’infrastructures de transports terrestres de qualité. Les réseaux routiers et ferrés français couvrent l’ensemble du territoire et connectent la France à tous ses voisins euro-péens. Néanmoins, les ports français ne bénéfi -cient pas encore tous de connections optimisées aux réseaux fl uviaux desservant leurs hinterlands (gabarit inadapté, hauteur des ponts, fonction-nement des écluses…).

Les efforts en matière d’infrastructures portent par conséquent en priorité sur la desserte des ports ainsi que sur la régénération et la modernisation du réseau fl uvial.

2.1. Privilégier les dessertes terrestres des arrière-pays portuaires

Le réseau routier français regroupe autour d’un million de kilomètres de voies diverses. La route représente près de 90 % des marchandises trans-portées sur le territoire français en tonnes kilo-mètres. Elle est appréciée pour sa fl exibilité et sa fi abilité et a bénéfi cié d’un fort développement de ses infrastructures. Elle est par ailleurs très com-pétitive. Depuis 1985, les prix du transport routier ont diminué de 30 %.

Le réseau ferré est lui-aussi très dense. RFF (Réseau Ferré de France), gestionnaire de l’infrastructure ferroviaire française, gère près de 30.000 kilo-mètres de lignes sur lesquelles circulent chaquejour 15.000 trains de fret et de voyageurs. Ses lignes

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desservent l’ensemble des pays européens limitro-phes.

Le réseau national de pipelines transporte le pé-trole brut ou ses multi-produits (essence, kérosène, gazole, fioul domestique) et approvisionne les ter-ritoires français et européens. Le développement des modes massifiés et de l’offre logistique associée nécessite d’améliorer les connexions entre les ports et les réseaux fluviaux et ferroviaires, pour une meilleure compétitivité des modes massifiés.

Le gouvernement français a demandé d’intégrer la modernisation et la fiabilisation des dessertes des ports dans la stratégie des gestionnaires d’infrastructures ferroviaires et fluviales. Définissant les grandes orientations nationales d’infrastructures de transport pour moderniser et fiabiliser les des-sertes des ports, le gouvernement s’assure que les dessertes des ports deviennent bien prioritaires pour développer les modes massifiés.

Fig. 2 : Transport multimodal, trains chargés de conteneurs au port du Havre

(© Laurent Mignaux/METL-MEDDE)

2.2. Régénérer et moderniser le réseau fluvial

Le réseau navigable français s’étend sur environ 8.300 km. L’État est propriétaire de la plus grande partie de ce réseau, mais celui-ci est placé sous la responsabilité de plusieurs gestionnaires. Depuis le 1er janvier 2013, Voies navigables de France gère la majeure partie de ce réseau (6.740 km), la Compagnie nationale du Rhône et l’État en gérant respectivement 500 km et 400 km.

Une partie du domaine public fluvial a été trans-féré par l’État aux collectivités territoriales lors d’une première vague de décentralisation dans les années 1990.

Avec l’émergence des préoccupations écolo-giques en France au milieu des années 1980, le

renouveau de la voie d’eau, quelque peu oubliée dans la première moitié du XXème siècle, s’impose comme une nécessité. L’État créé l’établissement public Voies navigables de France en 1991, sous l’impulsion du Premier ministre Michel Rocard, et lui confie en gestion la majeure partie du domaine public fluvial. Un peu plus de 20 ans après la créa-tion de l’établissement, la voie d’eau française continue, malgré le contexte de crise économique actuel, à gagner des parts de marchés. Entre 2000 et 2010, la part modale du fluvial évolue favor-ablement, de 3,4 à 4,3 % (Source: Eurostat).

Cet effet, qui s’explique en partie par le rattra-page des investissements, se poursuit et contribue notamment aux objectifs de l’État en matière de transition écologique et énergétique. Ainsi, la voie d’eau française a vocation à se développer et à s’imposer comme un mode de transport massifié, économiquement pertinent, bénéficiant d’un ré-seau modernisé et géré comme un véritable sys-tème industriel.

Afin de répondre à ces enjeux stratégiques, l’essor du transport fluvial repose aujourd’hui sur la régé-nération et la modernisation du réseau des voies navigables, ainsi que sur le développement com-mercial de la voie d’eau. C’est pourquoi, répon-dant aux objectifs de report modal en accompag-nant le développement du trafic fluvial et assurant la sécurité des usagers et des agents, l’Etat et Voi-es navigables de France (VNF) ont construit, dans le cadre du projet ‘Voies navigables 2013’, un programme d’investissement sur cinq ans, visant à régénérer, mettre en sécurité et moderniser le réseau.

Le contrat d’objectifs et de performance en-tre l’État et VNF, pour la période 2011-2013, con-stitue la première phase de réalisation de ce programme. Il se décline en actions de mise en sécurité et de remise en état du réseau pour ga-rantir des niveaux de fiabilité et de disponibilité du service et des itinéraires. Il prévoit également de passer d’une maintenance curative des ouvrages et des infrastructures à une maintenance préven-tive, pour fiabiliser le niveau de service. Sur le réseau à grand gabarit, l’État a fixé à VNF des objectifs d’ouverture 24h/24, comme le font déjà nos voisins du Nord, avec une navigation libre toute l’année sur le réseau connexe à ce grand gabarit, sur la base de douze heures par jour, sept jours sur sept. Sur le réseau touristique, une offre de service sera mise en place qui tiendra compte de la saisonnalité de ce secteur et des besoins des différents usagers. Le contrat d’objectifs et de performance comprend enfin des opérations de développement sur le réseau à grand gabarit, dans une vision positive de l’évolution du réseau et en vue des objectifs de report modal vers la voie d’eau.

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Ce programme d’investissement présente égale-ment un volet consacré à la modernisation des méthodes d’exploitation et contribuera à mieux adapter l’offre de service aux besoins des usagers et à l’évolution des trafics français et européens et à supprimer les situations de travail pénibles ou ex-posées, notamment sur les ouvrages manuels, et optimiser les moyens nécessaires à l’exploitation par l’automatisation, la télécommande et la centralisation de l’exploitation des ouvrages ainsi que par le déploiement progressif des services d’information fluviale. L’État a fixé des objectifs de mise en con-formité environnementale, par la réalisation d’aménagements liés aux enjeux de biodiversité, de qualité de l’eau et de restauration des conti-nuités.

Fig. 3 : Chantier d’aménagement d’une écluse sur la Meuse

(© Laurent Mignaux/METL-MEDDE)

Cet effort s’ajoute au plan de relance portuaire, qui comprend un volet consacré à l’amélioration de la desserte fluviale de nos ports.

3. LES NOUVELLES TECHNOLOgIES AU SERVICE DU DEVELOPPEMENT DURABLE DE LA TRANSITION ECOLOgIQUELe développement de l’activité fluviale et mari-time doit non seulement être porté par des infra-structures de qualité, mais aussi contribuer à des transports plus performants et plus respectueux de l’environnement. Pour réduire les émissions et la consommation d’énergie, la modernisation de la flotte et le développement de carburants alter-natifs, comme le GNL, pour les bateaux et les na-vires passent par des innovations technologiques.

3.1.Moderniserlaflottefluviale

En France, le plan de déchirage, intervenu dans

les années 1990, a permis de restructurer le mar-ché et de le préparer à la libéralisation intervenue en 2000. Depuis, la flotte française augmente en productivité en conservant la même capacité d’emport (un million de tonnes avec un nombre plus réduit de bateaux). Les plus petits bateaux (Freycinet) sont remplacés par des bateaux de 1.000 à 1.500 tonnes qui desservent les bassins fermés du réseau à grand gabarit français. Ces bateaux sont souvent achetés d’occasion aux Pays-Bas ou en Belgique. Dans ces deux pays en effet des investissements massifs ont eu lieu depuis 2005 dans des unités neuves et de grande taille (jusqu’à 3.000 tonnes).

La France considère que pour que le mode flu-vial demeure une alternative au transport routier, il est nécessaire de poursuivre, voire d’accélérer, l’adaptation et le renouvellement de la flotte en vue:

• de répondre aux besoins des chargeurs. Ainsi de nouveaux bateaux Freycinet (la flotte Freycinet actuelle a environ 60 ans de moyenne d’âge) doivent être construits afin de maintenir la des-serte du réseau à petit gabarit ; des grands ba-teaux modernes doivent arriver sur le marché (entre 1.000 et 1.500 tonnes) afin que le trans-port fluvial poursuive les économies d’échelle.

• De répondre aux enjeux environnementaux. Il s’agit de limiter les émissions des moteurs dont la longévité ne permet pas rapidement de passer aux nouveaux standards. Il convient de travailler sur la conception des coques et des moteurs afin de limiter la consommation en énergie.

Dans le cadre d’une gestion modernisée du ré-seau et d’une meilleure gestion du trafic, la France poursuit le déploiement des services d’information fluviale et notamment incite les entreprises ayant équipé leur bateau avec un transpondeur AIS à installer des équipements d’aide à la navigation afin que le système soit pleinement opérationnel (lecteur de carte ECDIS, GPS).

Un plan d’aide à la modernisation de la flotte flu-viale a donc été mis en œuvre par le gouverne-ment français et VNF pour la période 2008-2012 doté d’un montant de € 16,5 million. Un projet de plan couvrant la période 2013-2017 vise plus particulièrement à favoriser l’achat de bateaux ou moteurs neufs ou modernes répondant à des standards environnementaux stricts, allant au-de-là des normes en vigueur.

Plusieurs solutions technologiques sont aujourd’hui envisagées pour développer de nouveaux ba-teaux fluviaux et adapter les motorisations de la flotte existante pour en particulier réduire les émis-sions de polluants tels que les oxydes d’azote et les particules fines.

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Tout comme dans le secteur maritime, la propulsion au gaz naturel liquéfié s’expérimente. Toutefois, si cette solution est pertinente pour la construction d’unités neuves, d’autres solutions technologiques doivent être adaptées pour la flotte existante, en particulier pour la ‘flotte petit gabarit française’. Pour ces bateaux, l’installation de moteurs diesel-électrique fait aujourd’hui l’objet d’une attention particulière, au regard des gains sur la consom-mation, de la réduction des émissions polluants lo-caux avec des moteurs à régime constant, et une meilleure gestion de la puissance motrice suivant les secteurs de navigation.

L’évolution du cadre réglementaire devrait en outre contribuer à ce processus de modernisation de la flotte. La Commission européenne envisage en effet de réviser la directive 97/68/CE relative aux mesures à prendre contre les émissions de gaz et de particules polluants provenant des moteurs à combustion interne destinés aux engins mobiles non routiers.

Fig. 4 : Transport fluvial sur la Seine(© Laurent Mignaux/METL-MEDDE)

3.2. Développer l’avitaillement des navires au gNL

Avec l’entrée en vigueur de l’annexe VI de la con-vention MARPOL à l’OMI au 1er janvier 2015, les navires devront réduire leurs émissions de soufre en Manche, en mer du Nord, en mer Baltique et le long des côtes des États-Unis d’Amérique et du Canada. L’emploi des carburants marins tradition-nels, comme le fioul lourd (HFO), ne répond pas à cette nouvelle réglementation. Des solutions tech-niques sont nécessaires à mettre en œuvre pour développer le transport maritime en respectant l’environnement. Des solutions alternatives exis-tent en effet tel que l’utilisation de filtres, appelés scrubber, l’emploi du gasoil marin ou du gaz na-turel liquéfié (GNL).

Selon l’OMI et l’Union européenne, l’emploi du GNL constitue une réponse particulièrement adaptée et innovante aux futures normes environnemen-tales, parce que ce carburant répond excellem-ment à l’ensemble des conditions posées par les textes de l’OMI et communautaires. Ainsi, par rap-port au fioul lourd, le GNL entraîne une réduction de 100 % des émissions de dioxyde de soufre, de

100 % des particules, de 80 % des oxydes d’azote et de 25 % de dioxyde de carbone.

Selon certaines études (Autorité maritime danoise, TRI ZEN), le prix de ce carburant serait néanmoins supérieur au fioul lourd mais inférieur au gasoil marin, ce dernier étant, à l’heure actuelle, 40 à 50 % plus cher que le fioul lourd. Le prix du GNL serait également moins sensible aux variations des cours du pétrole comparé à celle des carburants traditionnels. La flotte mondiale de navires propul-sés au GNL est donc en constante progression, et pourrait atteindre au moins 1.000 navires alimen-tés en GNL vers 2020. Un saut majeur est interve-nu avec la mise à flot du ‘Viking Grace’, ferry de croisière, alimenté au GNL, opérant en mer Bal-tique entre la Finlande et la Suède. Le volume de consommation du GNL comme carburant marin est en augmentation et devrait atteindre 4 à 5 mil-lions de tonnes en 2020 (Source: DNV).

Le passage au GNL va au-delà d’un simple changement de carburant marin. Il implique la création d’une nouvelle filière industrielle pour concevoir et fabriquer les installations spéci-fiques de soutage et le développement des ac-tivités de construction navale, qui se traduit par l’adaptation des motorisations ou la construction des unités neuves. Ce qui représente des perspec-tives non négligeables pour les chantiers navals. Cette nouvelle filière industrielle doit s’appuyer sur des domaines d’excellence en ingénierie comme la conception de citerne et de réservoirs mais aus-si de systèmes de soutage. Ce nouveau carburant peut favoriser la construction de navires neufs et relancer ainsi la construction navale.

Fig. 5 : Ferry manœuvrant dans le port de Marseille(© Laurent Mignaux/METL-MEDDE)

4. L’AMBITION D’UNE STRATEgIE NATIONALE POUR LES TRANSPORTS FLUVIAUX ET MARITIMESLe développement des transports fluviaux et mari-times s’inscrit dans une vision stratégique qui porte sur la qualité des services rendus.

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4.1. La réforme de Voies Navigables de France

Depuis sa création en 1991, le principal gestion-naire de la voie d’eau, Voies Navigables de France, bénéficiait, pour la réalisation de ses mis-sions, de l’appui des services de navigation de l’État et de certaines directions territoriales de l’État, qui étaient mis à sa disposition.

Toutefois, cette organisation ne permettait pas d’assurer une continuité du service optimale sur l’ensemble du réseau ou encore d’optimiser l’allocation des moyens.

Face à ce constat, le législateur a voulu regrou-per la collectivité de travail dans un seul et unique établissement, placé sous l’autorité d’un direct-eur général disposant de tous les leviers d’action nécessaires à la réalisation de ses missions. Ainsi, la loi du 24 janvier 2012, votée à l’unanimité en deuxième lecture au Sénat, regroupe depuis le 1er janvier 2013, au sein d’un même établissement public administratif, les 4.400 agents des services déconcentrés de l’État et les 400 salariés de droit privé de VNF. Ce rapprochement permet au nouvel établisse-ment d’instaurer une véritable communauté de travail et de maîtriser la totalité des moyens indis-pensables à son action.

Ce rapprochement permet également au nouvel établissement public d’améliorer son organisation territoriale. Par exemple, VNF prépare actuelle-ment avec le soutien de l’État, la création d’une 7ème direction territoriale en Bourgogne, en lieu et place de trois anciens services. Cette nouvelle organisation qui est entrée en vigueur le 1er jan-vier 2013, permet à l’établissement, sur le territoire concerné, de gagner en efficacité et d’avoir une capacité d’action plus réactive et plus homogène sur le réseau.

En outre, de nouveaux leviers d’action sont égale-ment donnés à VNF pour lui permettre de mieux valoriser son domaine et de trouver de nouvelles ressources à consacrer à la restauration du ré-seau.

4.2. La relance portuaire nationale

Avec la mise en œuvre de la réforme portuaire de 2008, le transfert de l’outillage et du personnel aux opérateurs privés s’est achevé en juillet 2011 et la fiabilité des places portuaires françaises s’est améliorée. Les grands ports maritimes ont retrouvé les moyens d’une saine compétition avec les au-tres ports leaders européens. Le gouvernement affirme son ambition pour

l’ensemble de son système portuaire, afin de don-ner à la France une place de premier rang dans le commerce international comme point d’entrée ou hub européen, et pour contribuer au dével-oppement industriel, économique et social du pays.

Situés à l’interface de routes maritimes et de réseaux de transports multimodaux, les ports français sont au cœur de la chaîne logistique d’approvisionnement des territoires. Ils ont voca-tion à accueillir les multiples activités dans les sec-teurs logistique et industriel, notamment dans le secteur énergétique ou sur les filières industrielles d’avenir.

A ce titre ils concilient ambition logistique, industri-elle et aménagement, dans un souci d’excellence environnementale.

Les ports français sont des ‘architectes’ de solu-tions logistiques maritimes et terrestres sur un hin-terland de portée européenne. Pour cela, les ports se positionnent comme des coordonna-teurs, démontrant une forte valeur ajoutée dans la mise en place de chaînes logistiques intégrées, économiquement compétitives et pérennes, fa-vorisant les moyens massifiés, afin d’attirer et fidé-liser les opérateurs et les clients.

Les zones portuaires sont, de par leur position géographique, de véritables pierres angulaires du développement industriel du pays. Les ports fran-çais ont vocation à devenir les lieux d’implantation privilégiés d’activités industrielles et économiques génératrices de trafics maritimes. Pour cela, ils ont un besoin impérieux de maîtriser la gestion de leurs espaces et de leurs capacités d’accueil.

Les ports français développent ainsi une approche intégrée d’aménageur et de gestionnaire de leurs espaces dans toutes leurs composantes: industri-alo-portuaires, logistiques, naturels, sans négliger l’interface ville-port, et ce en liaison avec les terri-toires. Les ports ont des responsabilités spécifiques vis-à-vis de leur domaine naturel, responsabilités qu’ils exercent, le plus souvent, en partenariat. Ils s’attachent à une meilleure prise en compte des enjeux environnementaux dans le respect de leur juste équilibre avec les enjeux économiques, équilibre dont l’État est le garant.

Pour mettre en œuvre cette ambition, les ports peuvent s’appuyer sur plusieurs leviers : la politique d’investissements priorisant les projets générateurs de croissance, d’emploi et d’innovation, la pro-motion du dialogue social sur la place portuaire, la valorisation des actions en matière de sécurité des personnes et de sûreté, le développement des compétences, l’influence du système portuaire français au niveau européen, le développement d’une marque forte et commune.

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Fig. 6: Porte-conteneurs à quai dans le port industriel du Havre

(© Laurent Mignaux/METL-MEDDE)

En présentant une stratégie globale pour les modes massifiés, le gouvernement fixe ainsi un cap ambi-tieux pour développer les transports maritimes et fluviaux et répondre aux enjeux d’une nécessaire transition écologique.

Although they have been boosted by a strong growth of maritime and inland navigation trans-port, ports and inland waterway development will only be achieved with high-level engineering and cutting-edge technology as answers to the social, environmental and economic challenges of the XXIst century. This development should be support-ed by quality infrastructures and must foster more

efficient transports contributing to the inevitable ecological transition. The fleet must be upgraded and boats and ships should use alternative fuels in order to reduce emissions and energy consump-tion, but for that, technological innovations are still required. These developments are part of the strategic vision of the services to the community by high-volume transports.

SUMMARY

Dynamisés par des croissances fortes des transports fluviaux et maritimes, les ports et les voies naviga-bles ne peuvent se développer qu’avec l’appui d’une ingénierie de haut niveau et de technolo-gies de pointe pour répondre aux multiples défis sociaux, environnementaux et économiques du XXIème siècle. Ce développement doit être porté par des infrastructures de qualité et contribuer à des transports plus performants, prenant toute leur

part à la nécessaire transition écologique. Pour réduire les émissions et la consommation d’énergie, la modernisation de la flotte et le développement de carburants alternatifs pour les bateaux et les navires requièrent encore de nombreuses inno-vations technologiques. Ces développements s’inscrivent dans une vision stratégique des servic-es rendus par les transports massifiés à la société.

RESUME

Obwohl es starkes Wachstum im See- und Binnen-transport, bei den Häfen und den Binnenwasser-straßen gegeben hat, kann eine weitere Entwick-lung nur mittels hoher technischer Standards und Spitzentechnologien erreicht werden, als Antwort auf die sozialen, ökologischen und ökonomischen Herausforderungen des 21. Jahrhunderts. Diese Entwicklung sollte durch qualitativ hochwertige In-frastruktur unterstützt werden und muss zu einem leistungsfähigen Transport beitragen unter Berück-

sichtigung, dass ein ökologischer Übergang not-wendig ist. Die Flotte muss verbessert werden und die Boote und Schiffe sollten alternative Brennst-offe verwenden, um die Emissionen und den En-ergie-verbrauch zu reduzieren; aber um das zu erreichen, sind noch zahlreiche technische Inno-vationen erforderlich. Diese Entwicklungen sind Teil einer strategischen Vision von Dienstleistun-gen, durch den Gütertransport für die Gesellschaft übernommen.

ZUSAMMENFASSUNg

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KEY WORDS: locks, remote control, traffic man-agement

MOTS-CLES: écluses, téléconduite, gestion du trafic

ThE RhONE TRAffIC MANAGEMENT CENTRE

CENTRE DE GESTION DU TRAfIC DU RhôNE

PIERRE EMMANUEL PAREAU

Head of Maintenance and New Projects DepartmentCompagnie Nationale du Rhône

2 rue André Bonin - 69316 Lyon Cedex 04France

Tél: +33 (0)4 72 00 69 65E-mail: p.pareau@cnr.tm.fr

ROMAIN BARTHELET

Responsible of Automatic Systems DivisionCompagnie Nationale du Rhône

2 rue André Bonin - 69316 Lyon Cedex 04France

Tél: +33 (0)4 72 00 68 88E-mail: r.barthelet@cnr.tm.fr

Fig. 1: CNR’s developments on the Rhone

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1. THE RHONE-SAONE CORRIDOR, A MEDITERRANEAN ARTERYThe Rhone has been developed by the Compag-nie Nationale du Rhône in the framework of a concession with the threefold objective of provid-ing hydroelectricity production, navigation and ir-rigation.

The wide-gauge section of the Rhone is 330 km long and permits the passage of multiple barge convoys of 4,400 tonnes. It has a guaranteed draught of 3 m and a head clearance of 6.30 m.

In 2011 river traffic amounted to 5.8 million tonnes for a flow of 1,300 million tonnes x km. North of Lyon, the Rhone is prolonged by the Saone river which also allows the passage of wide gauge ves-sels. Together they provide a navigable waterway more than 500 km long that serves the major in-dustrial and agricultural regions of southern and eastern France.

Since the Saone and Rhone flow into the Mediter-ranean, their natural outlets are the ports of Mar-seille and Sète, the latter being linked to the river by the Rhone canal. Nearly half (about 45 %) of the traffic using the basin passes via one of these two seaports, though Marseille-Fos outweighs Sète in terms of volume.

This highlights the importance of having a competi-tive maritime interface for the stakes of river devel-opment. However, taking this example alone, one out every two containers passes via the ports of northern Europe, thus avoiding the Rhone, where-as our ports on the Mediterranean are obviously the natural points of entry for these containers.

The port reform set up in 2011 is therefore crucial for accelerating modal transfer from road to wa-terway. Its deployment over the past year has been encouraging for container traffic, which has increased at an annual rate of nearly 10 % since April 2011.

If other types of traffic are not as dynamic, we think that it probably due to the gloomy economic cli-mate and the resulting contraction in key sectors, such as the construction and automobile indus-tries. What is more, salt consumption was low dur-ing the winter of 2012 while cereal exports suffered a downturn, explaining the reduction of traffic in 2012 and putting an end to a decade of growth.

Nonetheless, there is a bright side. Although it is too early to predict a general resumption of ac-tivity, container traffic could set the example with modal transfer; port reform also promises posi-tive repercussions, even though confidence can

only be built through time. Lastly, the creation of a Rhone-Saone ports committee, in addition to the impetus provided by the government, should boost modal transfer.

In this context, the Port of Lyon EdouardHerriot pro-vides a good illustration: the volume of river traffic handled by the port has risen by more than 7 % over the year (compared to a fall for the basin) and it is heavily involved in container transport (+19 %). Thus, it forms the bridgehead and hub for river traffic, with an interesting and promising out-look for modal changes.

However, traffic can only develop sustainably through attracting new clients and new transport.

Changing logistic organisation and bringing new entities into the basin require considerable invest-ments.

The confidence that skippers and transporters are able to place in the waterway operator and in its capacity to stand by its commitments in the long-term is a decisive factor for success.

The arrival of new modern and high capacity units in recent years is proof of this confidence.

As the operator of the navigable waterway of the Rhone, CNR is bound to strengthen its commitment to modernise navigation, a process that began in 2003 following the signature of its new contract.

To this end, CNR started to implement a plan in 2004 that focuses on the following actions:

➢ Improving lock reliability➢ Commissioning a user information system (Infor-

hone.fr), producing ECDIS charts➢ Constructing new infrastructures (mooring

points, a container terminal at Port de Lyon)

The recent growth in traffic and the outlook for de-velopment highlight the need to adapt to meet the new challenges:

➢ Increasingly strict security and regulations for transport (monitoring hazardous substances, in-creasing numbers of passengers)

➢ Providing information to users and monitoring the passage of goods through the supply chain

➢ An increased workload for locks (traffic doubled from 1998 to 2009)

As part of its second five-year plan of Missions in the General Interest, CNR must pursue its activities in the following three areas:

➢ Continue and speed up the lock upgrading and reliability programmes

➢ Traffic management, provide new services to skippers and crews, by facilitating the growth in

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traffic and by integrating new information tech-nologies

➢ Prolong opening hours for commercial vessels (24h/24h)

Therefore, the Company has embarked on a proj-ect to ‘Upgrade the navigable waterway’ with the aim of passing through different stages from ‘lock operation’ to ‘traffic management’, by setting up a traffic management and monitoring centre and by speeding up the programme to upgrade and increase the reliability of the locks.

The first component of this project was to set up a Traffic Management Centre (CGN) whose long term mission is to manage traffic in real time and ensure remote control of the locks on the lower Rhone 24 hours a day.

2. THE MAIN PRINCIPLESSetting up the Rhone Traffic Management Centre meets the need to improve the level of service provided to the traffic and the need to optimise the management of the navigable waterway and the operation of the locks.

Managing the traffic on the river requires the permanent acquisition of information on traffic conditions, hydrometeorological conditions, the availability of the structures, specific conditions (warnings to the river traffic, incidents, damage, etc.), the position of boats and the goods trans-ported, in order to plan lock passages, supply in-

formation and guide skippers and crews.

Furthermore, the locks must be operated as effi-ciently as possible, in order to reduce waiting time and filling lock chambers without boats.

Traffic management must gather, centralise and analyse all the information required to control a constantly evolving situation.

Operating the locks requires a dialogue with the sailors, traffic forecasts, ordering boat passages, starting and monitoring lock passages and filling a database.

Therefore, traffic management and operating the locks complement each other, while the tasks in-volves are common to both, especially the acqui-sition and diffusion of information and the organi-sation of passages.

The management involved permits evolving from a fragmented view made up of each lock to a global view of the section of river in question.

At the same time, the workload involved in man-aging, operating and monitoring changes as a function of the overall situation, the density of traf-fic and external events.

Designing the organisation of these activities leads to seeking a solution that:

➢ achieves the reactivity required to adapt in real-time

Fig. 2: Block diagram of traffic management

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➢ ensures the continuity of operations➢ guarantees the level of security, traffic safety,

personal safety and the security of property

Fig. 3: View of the new traffic management software due for commissioning in 2013

3. THE PROJECT ORgANISATIONThe project is managed completely by CNR. The CNR Operations Division is the client for the proj-ect: it sets out the objectives, the functions, follows up the schedules for implementation and man-ages the global budget for the operation.

The CNR Engineering Division acts as design and engineering manager for the project: it sets out the general technical design and supervises de-velopment and implementation. It also builds the SCADA and the automated systems.

The tasks of adapting the electric and control and instrumentation systems, the development of video and local communications management software applications are outsourced to special-ised companies and overseen by the CNR Design Engineer.

4. PERIMETER AND gENERAL PRINCIPLES OF THE PROJECTThe perimeter of the project involves the fourteen locks on the lower Rhone, including Port Saint Louis and Barcarin which provide access to the port of Marseille.

Every operator at the remote-control centre has the technical capacity to operate any lock con-nected to the centre.

They can supervise two lock passages simultane-ously, except for the lock at Port Saint Louis, which

is controlled alone due to the presence of a lift bridge.

The telecontrol operator operates the lock ac-cording to the same procedures as they would if controlling locally (control of cycles). They have similar interfaces (the same control buttons) and video and PA equipment to those used when op-erating from a control tower. The locks can also be operated from the control towers.

The telecontrol project has been subjected to safety studies and an experimental phase on two locks. The telecontrol centre has ergonomically designed controls and information that are the same for all the locks.

Fig. 4: A lock supervision screen

The architecture of the equipment used at the telecontrol centre is similar to that used for the telecontrol of CNR’s hydropower plants and it is based on an ABB micro-SCADA.

Communication is ensured via CNR’s existing com-puter network for both control and instrumentation flows and video, sound, etc.

The telecontrol is adapted to existing systems. The oldest have been modernised and new equip-ment has been deployed or adapted to the locks to ensure telecontrol (video and interphone equip-ment, etc.) and satisfy the specifications of safety and ergonomics studies.

The local adaptations of automation systems are implemented:

➢ without impeding or representing a risk for navi-gation: tests are performed on the platform and during programmed stoppages of navigation (in March);

➢ with the minimum impedance for all the oth-er actions that have to be performed on the locks (civil engineering maintenance, mechan-ics, electrical renovation, etc.). This constraint was taken into account when phasing deploy-ment.

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5. ORgANISATION AND OPERATION OF THE RTMC5.1. Organisation

Defining the organisation of the river traffic man-agement centre requires knowledge and taking account of:

➢ elements that characterise river traffic ➢ tasks to be performed that stem from the mode

of operation adopted

Analysis of river traffic has highlighted substantial seasonal variation, with the number of lock pas-sages varying from 4,000 in January to 11,000 in July.

Whatever the season, most of the traffic occurs during the day as night-time traffic only makes up 13 % of the total.

The number of river traffic technicians is deter-mined so that navigation is managed under the same conditions as presently (in terms of lock pas-sage time and monitoring). Therefore, number of river traffic technicians remains the same through-out the year, even if there is less traffic from Oc-tober to March, which could justify a lower work-force.

The number of technicians is set at 36 organised in teams working in 3 eight-hour shifts or in 2 eight-hour shifts.

There are seven technicians on duty from 6 a.m. and 10 p.m. and four technicians at night depend-ing on the progression of night-time traffic.

The teams are supervised by three managers.

5.2. Operating Principles

A river traffic technician can select any lock from their workstation (validated in remote control mode) that they manage in OPERATING mode or in MONITORING configuration.

They can perform a maximum of two tasks simul-taneously:

➢ monitor two selected locks (one selection per ½ workstation)

➢ operate two locks (1 lock per ½ workstation)➢ they can operate a lock (on a ½ workstation)

and monitor a selection of locks (on the other ½ workstation)

NB: except for Port St Louis du Rhône which has a lifting bridge: when a river traffic technician se-lects this lock in operating mode, he cannot oper-

ate another lock or monitor a selection of locks.

Fig. 5: Telecontrol console

In case of system failure, all the locks can be con-trolled from their control towers, the switch to local control is performed in less than 30 minutes.

6. OPERATINg SECURITYOperating security guarantees the safety of pas-sengers and personnel and the reliability of the structures is one of the keys of the success of the lock telecontrol project.

This element was taken into account from the out-set of design and will be until the new system is commissioned.

A global approach has been adopted that is based on:

➢ Continuous action during different steps of the project to define the security studies to be car-ried out and the sensitive points to be given specific attention. It is manifested by assistance given to the owner by an independent external consultant.

➢ A working group dedicated to risk studies, com-posed of representatives of the designers (own-er and engineer), and CNR traffic management personnel (lock keepers, technicians, local man-agers). During its different meetings, this work-group fuels overall reflection on risk studies.

➢ Performing risk studies of SIST law type for each lock managed by telecontrol.

➢ The aim of the studies performed is to present a Preliminary Safety Study in conformity with the SIST law 2002-3 of January 3, 2002 relating to the safety of transport infrastructures and systems.

A Preliminary Safety File (DPS) before carrying out the works (the subject of this document is attached in the appendices),

➢ A safety report drawn up by an expert or a qual-ified organisation

➢ A Safety File (DS) before the operation started.

The risk analysis performed on the locks of Pierre-Bénite, Bourg les Valence and Avignon taking into account the current installations, operated

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locally, showed that the level of safety was global-ly satisfactory. The current system therefore served as reference to evaluate the GALE (Globally At Least Equivalent) level of the telecontrol project’s safety.

The main impact on safety of implementing the telecontrol project is to eliminate both the pres-ence of a lock keeper capable of intervening in the lock chamber and the visual control per-formed by the lock keeper of a large number of more or less dangerous situations.

Consequently, the three measures considered that compensate for the lock keeper’s distance from the site are the following:

➢ Reinforcing the video system composed of cameras, especially at the heads of the locks, which requires:

• Carrying out an ergonomics study on the de-velopment of the TCMC and supervision

• Carrying out a study of the camera positions➢ A standby duty call with fast intervention in the

case of a technical problem or incident➢ The presence of seasonal workers at certain

locks to inform pleasure boat crews of the right procedure to follow

In conclusion, the risk analysis showed that for each risk identified, the measures considered to reduce it were considered adequate enough for level of safety of the installation to be globally sat-isfactory and equivalent to the safety level of the reference installation.

7. ARCHITECTUREThe architecture of the telecontrol comprises four main systems which are the following:

➢ The control and instrumentation for remote lock operations

➢ The emergency stop system to ensure the safety of the lock by tripping the power supply to the control and instrumentation and operating de-vices

➢ Video-monitoring to ensure visual control around the chamber and around the lock

➢ The vocal communication management sys-tem (VHF radio with the boats, PA system in the chamber and lock lay-bys to diffuse spoken and recorded messages, and telephones)

All the systems make use of CNR’s fibre-optic net-work, a computer network with a data flow rate of 1Gbits/s allowing real-time video image transmis-sion. This network is backed up by an emergency network which, in case of failure of the main net-work, guarantees a bandwidth of 1Gbits/s dedi-cated to the telecontrol.

Fig. 6: Flow diagram of the four systems

7.1. The Control and Instrumentation System

This consists in interfacing the local automation devices (operating PLCs known as ‘APN’, PLCs ensuring ultimate safety known as ‘CSU’, general service PLCs, APX, with computerised systems with man-machine interfaces called ‘SCADA’ devel-oped on the basis of the micro-SCADA software from ABB.

Fig. 7: Control and instrumentation system

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The local SCADAs dialog with the SCADA central servers at the RTMC that manage all the displays and controls on the 8 operator consoles at the RTMC. The central RTMC SCADA plays the role of main switchboard: it connects an operator console with one or more locks.

The RTMC operator has the process information of the locks they manage on five screens. These five screens allow him to manage two locks:

➢ On the 1st screen: positions and statuses of the devices of the 1st lock

➢ On the 2nd screen: faults affecting the devices or the system of the 1st lock

➢ On the 3ème screen: positions and statuses of the devices of the 2nd lock

➢ On the 4ème screen: faults affecting the devices or the system of the 2nd lock

➢ On the 5ème screen: selection of locks being managed

Screens 1 and 2 compose the left ½ console. Screens 3 and 4 compose the right ½ console.

By using their five screens, the operator can also send macro-commands interpreted and con-trolled by the site APN PLC:

➢ cycle commands: ‘upstream cycle’, ‘down-stream cycle’, ‘stop’, ‘confirmation’

➢ selection commands (selection of devices, functions, etc.)

The RTMC operator has a push button situated on each ½ console of their workstation. It allows

them to stop with certainty (by tripping the elec-tric power supply) all the devices of the lock they are operating. This action, called ‘stop process’, is ensured by the normal channel of the control and instrumentation channel system.

Fig. 9: RTMC operator workstation – instrumenta-tion and control part

The local and central servers are replicated in number and in separate geographical sites in or-der to ensure optimal system availability.

These systems considered as belonging to CNR’s core activity have been developed by teams internally in view to ensuring full control over the maintenance of these tools. The latter (PLCs, SCA-DA servers) are also used for other CNR operating systems, in particular the entire management of hydropower production.

7.2. Remote Emergency Stops

The stop process described previously uses the normal computerised channel of the instrumen-tation and control system. It is replicated by an independent system developed on the basis of specific PLCs known as ‘APS’.

Fig. 8: Switching system

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Each lock is equipped with an APS PLC linked to its correspondent at the RTMC by CNR’s Ethernet IP communication network. The safety channel thus built permits the transmission of the emergency stop request that the RTMC operator can activate by pressing a button on a wall-mounted mimic diagram panel.

The mimic diagram panel is equipped with four-teen push buttons (one per lock). The implementation, installation, programming and maintenance of the APS were specified in conformity with standard IEC 61-508. The Safety Integrity Level (SIL) defined by this standard has been assessed for locks and level 3 was chosen.

The entire emergency stop system, from the trip push-button to the actuators on the site has been specifically designed and developed to obtain SIL3 certification.

Fig. 10: The remote emergency stop system

7.3. The Video-Monitoring System

Based on a reference framework of about sixteen cameras located at strategic positions around the chamber and the approach areas, the RTMC vid-eo-monitoring system permits controlling the cam-eras and viewing the images on three dedicated screens on each ½ control console.

The cameras must allow verifying the position of the boats in the chamber, which should be cor-rectly lashed, especially in the case of pleasure crafts – whose crews are less experienced with this

type of manoeuvre – and visually check that the lock passage proceeds smoothly.

Electronic encoders have been installed in the chambers. They transform the analogue video sig-nals received by the cameras into digital signals that are then compressed in MPEG4 standard. Each encoder then multicasts the images on the IP network.

The encoder is programmed in order to diffuse im-ages with:

➢ CIF quality (352 x 288 pixels), 2 CIF (704 x 288 pix-els) or 4 CIF (704 x 576 pixels)

➢ refreshment every 25, 12 or 6 images per sec-ond

➢ an IP rate that can be limited (300 kbits/s to 3000 kbits/s)

In order to ensure high quality, most of the images are diffused in 4CIF, 25 images per second without limiting the bit rate.

Fig. 11: The video system

All the images are managed at the RTMC by a main server that diffuses them from the encoders

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located on the sites. This video server is linked to the RTMC SCADA server, as to identify the locks managed by the operator of each console. It is replicated to guarantee good video system avail-ability.

The images are recorded digitally on a server and can be accessed from a specific workstation re-served exclusively for maintenance. The operators only have access to real-time images. The record server is used as a backup in case the link with the RTMC server fails.

7.4. The Vocal Communication System

This system provides the RTMC with the same com-munications resources as those that were used by the lock-keeper in his control tower. To achieve this, local communications, whether telephone, VHF radio or via the PA system, are transmitted to the RTMC via the CNR computer network.

Fig. 12: Vocal Communication System

The architecture of this system is quite similar to that of the instrumentation and control and the video, with:

➢ a local acquisition system: for the audio, the sys-tem is non-overlapping:

• For telephone communications, acquisition is ensured by Media Gateway telephone systems that convert analogue telephone messages for transmission via IP networks. They permit han-dling conventional telephone calls made to the locks.

• For VHF radio and the PA system, acquisition is ensured by ATA equipment (analogue tele-phone adapter) that converts VHF and PA sig-nals (command and voice signals) for the IP network.

➢ a central management and switching system: this system is called CTI (telephone-computer coupling). It entails a central server at the RTMC that links the operator’s audio interfaces with the lock systems for which he is responsible.

The operator has a single and ergonomic ‘Audio’ interface on their console that allows them to use any of the communication channels connected: VHF, telephone, PA, interphone.

Fig. 13: View of the vocal command station (VHF, telephone, PA system)

8. THE WORKSThe works essentially comprise the following:

➢ the equipment of a development and mainte-nance platform at Pierre Bénite. This platform accommodates the entire project team, the design and engineering management and the development teams. It also allows testing all the systems before their deployment in production. Tests are performed with software to simulate the hydraulic, electric and automation behav-iour of two locks. Two operator workstations at the RTMC have been installed on this platform.

➢ the works to equip the centre at Châteauneuf and the installation of remote control equip-ment. These works were carried out from Sep-tember 2008 to February 2009.

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➢ the development of specific software and the procurement of computer hardware (video, vocal communication, operation). The devel-opment of software applications linked to the instrumentation and control system was per-formed by CNR’s teams, whereas the develop-ment of the video and vocal communication systems was entrusted to external companies under the supervision of CNR.

➢ the local adaptation of the locks, comprising in particular works on automation devices, and improving the video equipment. This adapta-tion was done according to scheduling dic-tated by the annual stoppage of navigation on the Rhone which takes place every year during March for a period lasting from 7 to 10 days. Modifications made to the electrical system and automation devices were prepared the previous year (from April to September), then deployed from October to February, in parallel with the existing systems and finally connected when navigation was stopped in March. There-fore, in March 2008, two locks, Avignon and Bourg-les-Valence, were prepared locally. In March 2009, three other locks were ‘adapted’. Five more were adapted in March 2010 and the four remaining locks were adapted in March 2011. Once adapted, the locks can be con-nected to the centre outside the periods when navigation is stopped. The first two, Avignon and Bourg-les-Valence, were connected in April 2009, the three following locks were connected in November 2009, four in 2010 and the last four in autumn 2011.

➢ the connection of the locks of Port Saint Louis and Barcarin to CNR’s fibre optic network: these two locks on the southern end of the Rhone are not directly connected to CNR’s Ethernet net-work. A fibre optic link was laid along Barcarin canal in 2011 to link these two locks.

9. THE REMOTE MAINTENANCE SYSTEMCNR’s teams have developed system mainte-nance software in parallel with the telecontrol sys-tem.

This application is used for the remote monitoring of the equipment of the River Traffic Management Centre and the locks under telecontrol.

Several screens permit monitoring lockage opera-tions in real-time and checking the operation of the global system, perform initial diagnostics and visualise the faults and alarms.

In addition to well-designed ergonomics, the screens are accessible to all the personnel con-cerned (operation, maintenance) via the CNR intranet. The advantage of this is that the depart-ments involved are informed in real-time by the telecontrol system and it facilitates remote main-tenance and troubleshooting operations.

Fig. 14: View of the RTMC control screen

Fig. 15: View of alarms

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The wide-gauge section of the Rhone river is 330 km long, which, prolonged by the Saone river, forms a corridor linking southern and eastern France with the Mediterranean basin. The Compagnie Nation-ale du Rhône (CNR) holds the concession to oper-ate the Rhone river (navigation hydropower) and is currently carrying out a ‘Navigable Waterway Modernisation’ project aimed at progressively up-grading aspects ranging from ‘lock operation’ to ‘traffic management’, by developing a centre for traffic management and the remote control of the fourteen locks built on the Rhone.

The first five locks were commissioned in 2009, with

the other nine locks being commissioned in 2010 and 2011.

The originality of this centre, besides the fact that it manages a large number of locks from a single location, is its flexibility as it permits operating any lock from any console, meaning that the centre can be adapted to deal with the traffic at a given moment and the number of persons available in the centre.

The project has been designed and developed from the outset by CNR’s engineering teams.

SUMMARY

Long de 330 km, le Rhône à grand gabarit con-stitue, prolongé par la Saône, une artère fluviale reliant les régions du Sud et de l’Est de la France au bassin méditerranéen. La Compagnie Nation-ale du Rhône concessionnaire du Rhône s’est engagée dans un projet de ‘Modernisation de la voie navigable’ dont l’objet est de passer, par étapes, de la ‘manœuvre des écluses’ à la ‘ges-tion du trafic’, en créant un centre unique pour la gestion du trafic et la téléconduite des 14 écluses du Rhône.

Les cinq premières écluses ont été mises en service

en 2009, les neuf autres écluses en 2010 et 2011.

L’originalité de ce centre, outre le nombre d’écluses conduites depuis un seul point est la sou-plesse de fonctionnement qui permet de condu-ire n’importe quelle écluse depuis n’importe quel demi-pupitre, offrant ainsi une grande capacité d’adaptation en fonction du trafic et du nombre de personnes présentes.

Le projet a été conçu et développé par les équipes d’ingénierie de la CNR.

RESUME

Die Rhone ist 330 km lang und um die Saone ver-längert, bildet sie eine Flussader, die das südliche und östliche Frankreich mit dem Mittelmeer verbin-det. Die Compagnie Nationale du Rhône (CNR), Konzessionär für Transport und Wasserkraftanlagen auf der Rhone, ist zurzeit dabei, ein Wasserstraßen-Modernisierungs-Projekt durchzuführen, mit dem Ziel, schrittweise vom manuellen Schleusenbetrieb auf ein Verkehrsmanagement umzustellen, indem eine Zentrale für Verkehrsmanagement und eine Fernleitzentrale für die 14 Schleusen, die an der Rhone stehen, entwickelt wird.

Die ersten fünf Schleusen wurden im Jahr 2009

beauftragt, die anderen neun Schleusen folgen in den Jahren 2010 und 2011.

Das Alleinstellungsmerkmal dieser Zentrale ist ne-ben der Tatsache, dass sie eine große Anzahl von Schleusen von einer einzigen Stelle aus managt, ihre Flexibilität, da sie es gestattet, jede Schleu-se von jeder Konsole aus zu betreiben, was be-deutet, dass die Zentrale sich an die jeweilige Verkehrssituation anpassen kann, auch bezüglich des benötigten Personals.

Das Projekt wurde von dem CNR-Ingenieurteam entworfen und entwickelt.

ZUSAMMENFASSUNg

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KEY WORDS: Panama Canal, numerical model, physical model, lock design

MOTS-CLES: Canal de Panama, modèle nu-mérique, modèle physique, conception d’écluse

1. INTRODUCTIONIn the framework of the construction works of the new locks of the Panama Canal, the final design of the locks F-E system has been carried out us-ing both a physical scale model and a set of 1-D, 2-D and 3-D numerical models. The validation of F-E system final design had to be carried out in 16 months since this step was on the critical path with

respect to the locks construction schedule.

The physical model has been run in the Laborato-ry of the Compagnie Nationale du Rhône in Lyon while the numerical model studies were performed by MWH in Buenos Aires. Initially, numerical models had been run to fix the design to be tested in the physical model. Then, each model was run at the same time, allowing to crosscheck the results and to minimise the time to achieve the validation of the hydraulic performance of the F-E system.

2. THE THIRD SET OF LOCK PROJECT

NUMERICAL SIMULATIONS AND ExPERIMENTAL MODELS: ThE ExPERIENCE Of ThE NEw LOCKS Of

ThE PANAMA CANAL

MISE EN œUVRE COUPLéE DE MODèLES NUMéRIqUES ET DE MODèLES PhYSIqUES DANS

LE CADRE DE L’éTUDE DE CONCEPTION DES NOUVELLES éCLUSES DE PANAMA

SEBASTIEN ROUX

Laboratoire de Mesures et d’EssaisCompagnie National du Rhône

4, rue de Chalon sur Sâone - 69007 LyonFrance

E-mail: s.roux@cnr.tm.fr

NICOLAS BADANO

MWH ArgentinaMarcelo T. de Alvear 612C1058AAH Buenos Aires

ArgentinaE-mail: nicolas.badano@mwhglobal.com

Fig. 1: Third Set of Locks structure – Overall view

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The Panama Canal Authority (ACP) decided to build a new lane along the Panama Canal that will double capacity and allow more traffic. Along with this new lane, two sets of larger locks, referred to as the Third Set, is under construction as from 2009, one set of locks in the Pacific end and an-other one in the Atlantic side. Each set of locks will have three consecutive chambers with lengths varying between 427 m and 488 m, depending on the position of the inner gates, and a width of 55 m. The design ship is a so-called New Pana-max 13,000 TEU container carrier (366 m x 48.8 m x 15.2 m; CB = 65 %). Because water consumption is a major issue, each of the six new locks will be equipped with three Water Saving Basins (WSB).

This ‘3 locks & 9 WSB’ configuration will help to save 87 % of the water required for the transit of one ship between from Pacific ocean to the Ga-tun lake and the Atlantic ocean (as compared to a single lift lock with no WSB). Even though the new locks will be wider and longer than the exist-ing locks, they will consume 7 % less water than the latter when the WSB are used.

The New Locks F-E system is described on the Fig. 2:

This side wall F-E system is specific because of its double culverts configuration which allows for a balanced flow distribution along the lock cham-ber. The lock chamber can be filled (or emptied) both by the upper lock or Gatun Lake and by the lateral WSB.

The culverts dimensions are outstanding since the 8.30 m wide by 6.50 m high main culvert is wide enough to allow the transit of two railroads.

3. PRESENTATION OF THE MODELS USED DURINg THE FINAL DESIgN STUDY3.1. Numerical Models

State-of-the-practice software was used to study the different problems:

- Local head losses at the different system com-ponents were computed using 3-D models based on OpenFOAM, a formerly commercial code that has become freely available. Its main

Fig. 2: New Locks F-E system

Fig. 3: Pictures of the central flow divider, main and secondary culverts

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advantages over comparable commercial software are its high-performance (Linux-based, parallel processing), access to a worldwide fo-rum to request support, and its flexibility to intro-duce new features, if needed.

- The filling/emptying times and maximum flow ve-locities were calculated with a 1-D model based on the commercial software FlowMaster V7.

- The hawser forces were inferred from the water surface slope values correlated during previous design phases. The water surface slopes were obtained using a 2-D model based on Hidrobid software (a numerical code developed by Insti-tuto Nacional del Agua) which is similar to other software like Mike 21 – by DHI –, or Delft2D.

All the models went through calibration or valida-tion processes. The validation of OpenFOAM was based on comparisons with existing experimental results. The 1-D model was first calibrated by com-parison with experimental results from measure-ment carried out on the conceptual design physi-cal model and with the results of the 3-Dmodels. Then, when the physical model tests started, the results achieved were also used. The 2-D model was validated by comparing its results with the results obtained with software Delft2D and with measurements performed in the physical model.

3.2. Physical Model

A scale model, 60 m long and 10 m wide, repre-senting two lock chambers, three Water Saving Basins (WSB) associated to the lower chamber, one fore bay and one tail bay has been built at scale 1/30 in CNR laboratory.

Fig. 4: General view of the physical model

This model has been equipped with about 100 sensors in order to measure: - The water levels in the lock chambers, basins,

fore and tail bays- The longitudinal and transversal differential wa-

ter levels in the lock chamber (i.e. the longitudi-nal and transversal water slopes)

- The velocities and flow rate in the main culverts

and WSB conduits- The pressure in the culverts and downstream the

valves- The valve positions- The longitudinal and transversal hawser forces

(i.e. the longitudinal and transversal compo-nents of the hydrodynamic force exerted by the water on the ship’s hull)

In order to handle the amount of information, a dedicated program has been developed (with the Labview software), allowing:

- To look in real-time at every data transmitted by all the sensors equipping the physical model

- To operate the physical model manually, i.e. setting the position of every valves, the water level in every lock chambers or WSB

- To define the calibration equations of every sen-sors

- To program the parameters for the tests (initial water level, valves operating schedules, sensors activated for data acquisition)

- To record the sensors measurements in several format (Tension, intensity, physical model (i.e. scale) value and prototype value)

A set of three ship models (one 12,000 TEU Post-Panamax containership, one 8,000 TEU container-ship and one dry bulker) at scale 1:30 were used for carrying out the tests in the physical model aimed at measuring the total forces exerted on the ship’s hull and calculate the hawser forces and vessel displacements.

The tests have been carried out through four tasks, starting with tests in steady flow conditions used to assess the flow distribution along the lock cham-ber and assess the head losses in the F-E system. The two following tasks aimed at verifying the F/E system proposed in the tender design by the Con-tractor will permit to comply with the hydraulic performances requested by the ACP. The last task aimed at assessing the F/E system performance for debased conditions (i.e. for different equipment availability scenarios) but also for specific type of vessel other than the design vessel.

At the end of the study, more than 1,500 tests were performed on the physical model in one year.

4. COMBINED USE OF PHYSICAL MODEL AND NUMERICAL MODELSThe final design study of the New Locks F-E system has been performed by implanting simultaneously numerical model (1-D, 2-D and 3-D) and a physi-cal model. The model interactions are described in the Fig. 5 on the next page.

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The combined use of physical and numerical model is presented through three examples in the sections hereafter.

4.1. Calibration of the 1-D Model of the Lock F-E System

The entire F-E system has been modeled with the Flowmaster 1-D software, representing and setting the parameters of every component such as res-ervoirs, culvert, bends and valves, the most com-mon components of internal flow system being already available in the software library.

Anyway, some components such as the central flow connection present a very complicated hy-draulic shape whose head losses coefficient can not been set without additional calculations with 3-D model and measurements carried out on the physical model.

Fig. 6: Central flow connection

The physical model was equipped with flowme-ter and differential pressure sensors implemented along the F-E system, the measurement of the dis-charge and the pressure drop allowed to calcu-late the head losses of the different section, espe-cially between the complex hydraulic shapes.

Once the 1-D model has been calibrated, it be-comes a very efficient tool allowing to perform fast sensitivity analysis, in order to define the op-erating parameters (i.e. valve opening schedule) before testing them on the physical model.

The construction of two 1-D numerical models, one at scale 1/30 and the other at prototype dimen-sions, also gave very valuable information on the scale effects. Indeed, even if the flow condition is turbulent in the physical model at the selected scale (Reynolds numbers are ranging between 105 and 106) it does not represent completely well all the factors involved in the F/E processes. In particular the friction losses in smooth conduits are over-predicted (Reynolds numbers on the pro-totype are ranging between 107 and 108). Spe-cial considerations must be made to accurately compare results from the physical and numerical models and correction must be applied to the physical model results in order to obtain the per-formance expected on the prototype. According to the F-E operation (i.e. between the Gatun lake and a lock chamber, between two locks cham-bers, between a lock chamber and the ocean or between a lock chamber and a WSB), the F-E times have to be reduced from 4 % to 16 % and the discharge peaks values have to be increased from 4 % to 10 %.

Fig. 5: Combined use of numerical and physical model

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4.2. Assessment of the Flow Distribution Through the Lateral Ports

The F-E system designed for the New Locks of the Panama Canal is a ‘double-culverts lateral F-E sys-tem’.

It is composed by one main culvert (8.30 m x 6.50 m) connected to two secondary culverts (6.50 m x 6.50 m) in the centre of the lock chamber. Each secondary culvert feeds the lock chamber by means of 10 ports of 2 m x 2 m as shown on Fig. 7.

Achieving a balanced flow distribution along the lateral ports is something of first importance in or-der to have smooth filling conditions and limiting as far as possible the forces exerted on the vessel (and consequently the reaction forces applied in the mooring lines). Before running all the F-E sce-narios, a lot of measurements were carried out on the physical model in steady flow condition to as-sess the symmetry of the flow entering into the lock chamber. These measurements were carried out with propellers positioned at the mouth of the port in the lock chamber.

Anyway, the flow existing each of the twenty ports along one lock wall is not symmetrical with respect

to the vertical and horizontal axis of the port be-cause of the velocity component in the second-ary culvert.

numerical model gave very valuable data, such as distribution of the flow in every port and al-lowed to set an appropriate measurement proto-col for every port (i.e. to define if 1, 2 or 4 measure-ments were necessary to asses properly the port discharge).

All this set of data allowed to get an accurate and comprehensive knowledge of the flow conditions in every port and to validate the efficiency of F-E system regarding the flow distribution.

All this set of data allowed to get an accurate and comprehensive knowledge of the flow conditions in every port and to validate the efficiency of F-E system regarding the flow distribution.

4.3. Upgrade of Some Components of the F-E system Tender Design

The combined use of physical and numerical mod-el has demonstrated its full efficiency through the modification of one main culvert valve layout.

Fig. 7: Plan view of the half-lock chamber and its lateral feeding system

Fig. 8: Flow direction in the ports

Fig. 9: Numerical calculation Vs observation on physical model

Fig. 10: Original layout of the far main culvert valves

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The series of tests carried out on the physical model allowed to detect visually that some air was sucked in the main culvert downstream of the valve n° 5 (as shown on Fig. 10) but not down-stream to the valve n° 6 while both of them were opened according to the same schedule.

Fig. 11: Air entrainment under valve n°5

A 3-D numerical model of the valve has been im-plemented. It was validated on the basis of data measured on the physical model (especially pres-sure). It showed that the culvert asymmetry of the proposed layout generated a recirculation in the internal branch, increasing locally the head loss and creating unbalance flow conditions between the two valves even for the same opening sched-ule. It resulted from this diagnosis that the valves would have to be depenned and that a more symmetrical layout would have to be selected.

A new configuration of the valve layout has then been studied with the numerical model in order to set rapidly what would be the optimal elevation for the valves (with respect to the hydraulic per-formance and the excavation volume) and only

the retained configuration has been installed on the physical model for validation. It finally proved to work perfectly as expected according to the numerical model results.

This methodology has permitted in a very short time (i.e. less than three months) to ensure the re-sults by cross-checking the data on both model and to optimise the F-E system modification from a financial point of view.

5. CONCLUSIONS The studies to define the Final Hydraulic Design of the Panama Canal Expansion Project required the simultaneous implementation of several numeri-cal models performed in Buenos Aires Office and a scale physical model performed in a laboratory located in Lyon, France. In spite of the distance between the two teams, the combined use of physical and numerical models has demonstrated its full efficiency (in term of results accuracy and time saving) through the modification of some components of the F-E system.

It also allowed performing efficient crosschecking of the data, each model being used when need-ed to support and complete the results achieved on the other. The assessment of the model and prototype performance, especially the scale ef-fects, can not be obtained without implementing both models.

Due to recent progresses, it seems that the numeri-cal modeling is mature enough to complement the traditional approach based only in the use of physical modeling. Each one provides different advantages, allowing to overcome the charac-teristic limitation of the other. The combined use of these two types of models becomes an efficient way of predicting the behavior of the final proj-ect.

Fig. 12: Flow pattern downstream the far main culvert valves

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The final design of the Panama Canal new locks filling and emptying system has been performed by implementing simultaneously a physical mod-el in the laboratory of the Compagnie Nationale du Rhône in Lyon (France) and several numerical model in the offices of Montgomery Watson Harza in Buenos Aires (Argentina).

The combined used of physical and numerical model gives birth to a very powerful ‘hybrid’ mod-

el that helps the designer to minimise the calcula-tion time, crosscheck the results, access to a large number of data and improve the prediction of the hydraulic performance of the prototype. In the case of the final design study of the Post-Panamax locks, the combined use of a physical model, 1-D, 2-D & 3-D numerical models have proven to be a very efficient tool through a lot of cases which are presented in this paper for some of them.

SUMMARY

Les études de conception finale du système d’alimentation des Nouvelles Ecluses du Canal de Panama ont été menées en mettant en œuvre à la fois un modèle physique et plusieurs modèles numériques. Le premier a été construit au sein du laboratoire de la Compagnie Nationale du Rhône à Lyon alors que les seconds ont été développés par Montgomery Watson Harza à Buenos Aires. L’utilisation couplée des modèles physique et nu-

mériques permet de générer un modèle ‘hybride’ très efficace afin d’optimiser les durées des calculs et la quantité de données collectées, de procéder à des inter-validation des résultats et d’améliorer l’évaluation des performances hydrauliques du système d’alimentation des écluses. L’intérêt de l’utilisation d’un modèle hybride dans le cas de la conception du système de remplissage/vidange des écluses de Panama est illustré dans cet article à travers quelques exemples.

RESUME

Die endgültige Konstruktion des Füll- und Entleer-systems der neuen Schleusen am Panama Kanal wurde entwickelt, indem gleichzeitig ein physika-lisches Modell im Labor der Compagnie Nationale du Rhône in Lyon (Frankreich) und verschiedene numerische Modelle bei der Firma Montgomery Watson Harza in Buenos Aires (Argentinien) ein-gesetzt wurden. Die gekoppelte Anwendung eines physikalischen mit numerischen Modellen führt zu einem sehr lei-

stungsfähigen ‚Hybrid‘-Modell, das den Konstruk-teuren dabei hilft, Rechenzeiten zu minimieren, die Ergebnisse zu überprüfen, umfassende Da-tensätze zu erhalten und die Vorhersage zum hy-draulischen Verhalten des Prototyps zu verbessern. Im Fall der abschließenden Entwurfsstudie der Post-Panamax-Schleusen hat die Kombination eines physikalischen Modells mit 1D, 2D und 3D numerischen Modellen gezeigt, dass dies in vielen Fällen ein sehr effektives Werkzeug ist. Einige Mo-delle werden in diesem Artikel vorgestellt.

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1.THE ‘WORKINg WITH NATURE’ PHILOSOPHYPIANC established a standing committee on the environment at the Seville Congress in 1994. The committee later became the Environmental Com-mission – EnviCom. EnviCom meets twice a year in February at the PIANC headquarters in Brus-sels, Belgium and during the autumn in one of the member countries.

It thus met in Strasbourg in September 2008 at the invitation of the Central Commission for Navigation on the Rhine (CCNR) and in the autumn of 2010 in Le Havre, France at the invitation of the Grand Port Maritime du Havre (GPMH). Its last meeting in 2012 was held in Koblenz, Germany at the invita-

tion of the German Federal Institute of Hydrology (BAFG).

Paul Scherrer is the French representative within EnviCom.

In 2008, PIANC, on the proposal of the Environ-mental Commission, issued a position paper en-titled ‘Working with Nature’, which in fact led to the proposal of ‘doing things’ in a different order. The document was updated by PIANC in January 2011. It is available on the PIANC website in a wide range of languages (http://www.pianc.org/wwn-positionpaper.php).

The ‘Working with Nature’ philosophy can be summed up as carrying out projects in four steps:

GRAND PORT MARITIME DU hAVRE

‘wORKING wITh NATURE’ThE ‘EMERhODE’ PROJECT IN LE hAVRE

IMPROVING wATERwAY CONNECTIONS AND LAND RESERVES:AN OPPORTUNITY fOR ThE NATURE RESERVE?

‘œUVRER AVEC LA NATURE’LE PROJET ‘EMERhODE’ AU hAVRE

AMéLIORATION DES DESSERTES fLUVIALES ET RéSERVES fONCIèRES:UNE OPPORTUNITé POUR LA RéSERVE NATURELLE?

PAUL SCHERRER

Grand Port Maritime du Havre (GPMH)Projects and Engineering Director, Member of the Executive BoardBP 141376067 Le Havre CedexFrance

Tel: +33 (0)2 32 74 73 40Fax: +33 (0)2 32 74 73 45E-mail: dir.technique@havre-port.fr

JEAN-PIERRE gUELLEC

Grand Port Maritime du Havre (GPMH)Deputy Director and Projects Offi cerEMERHODE Project managerBP 141376067 Le Havre CedexTel: +33 (0)2 32 74 73 15Fax: +33 (0)2 32 74 73 62E-mail: jean-pierre.guellec@havre-port.fr

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1) Establishing project needs and objectives2) Understanding the environment in the whole

of the project area3) Making meaningful use of stakeholders’ com-

mitments to identify win/win opportunities4) Preparing initial project proposals/design that

meet the needs of navigation and the environ-ment

This is a subtle but important evolution in the way of approaching project development. ‘Working with Nature’ first of all considers the project objectives, firstly from the point of view of the natural system rather than from that of its technical design. This approach is seen to be extremely important, on the one hand, as a means of reducing the delays and frustrations of all kinds arising from the imple-mentation of projects and, on the other hand, as a means of better meeting all the expectations and optimising the sharing of benefits in the comple-tion of projects.

2. THE CREATION OF AN INTERNATIONAL DATABASEAt the end of 2012, the Executive Committee (Ex-Com) of PIANC, on the proposal of EnviCom, cre-ated an online international database designed to recognise projects conducted according to the ‘Working with Nature’ philosophy.

Two types of project can be entered:

- Those that have not yet been consented by re-ceiving the administrative authorisations which may be included in the database with the sta-tus of ‘Candidate for a Certificate of Recogni-tion’ if their development demonstrates the in-clusion of elements of the ‘Working with Nature’ philosophy

- Those that have been implemented or which have at least obtained all their consents and are therefore included in the database with the ‘Certificate of Recognition’

Recognition is given to projects by a unanimous jury representing all PIANC Commissions.

In addition, every four years, in conjunction with the PIANC World Congress, an Award will be grant-ed to the best ‘Working with Nature’-project.

3. THE EMERHODE PROJECT IN LE HAVREAn operation led by the Grand Port Maritime du Havre in the eastern part of the alluvial plain of the Seine Estuary can be seen as an application of the new ‘Working with Nature’ philosophy. The project involved the creation of a canal for inland navi-gation vessels connecting the Grand Canal du Havre with the Tancarville Canal together with the extension of the eastern part of the port industrial zone and the improvement of the environmental capacities of the Seine estuary Nature Reserve. After the public debate (which ran from October 8, 2009 to February 7, 2010), the project became much more ambitious and wider-ranging, its ob-jective now being to determine the most harmo-nious and sustainable development possible of an alluvial plain covering some 3,000 hectares. It is now called the EMERHODE project (the French acronym for ‘multimodal efficiency, economics and hydraulic networks: an opportunity for sustain-able development of the estuary’).

In accordance with the philosophy of ‘Working with Nature’, the studies for the project, for the time being, have taken place in four phases:

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1) Definition of the project needs and objec-tives. The main objectives of the project are to improve the waterway connections either for pushed convoys or for large-scale self-pro-pelled shipping, while reducing the congestion of road and rail traffic by limiting the need for opening of the movable bridges. Another of the project objectives is to develop the port in-dustrial zone in the eastern part of the alluvial plain of Le Havre while improving the environ-mental capacities of the Nature Reserve.

2) Understanding the environment in the whole of the project area consisting of estuary wet-lands. A large-scale mathematical model of the hydraulic functionalities of the whole area has been worked out. The model has more than 130,000 meshes. Its calibration has result-ed in the accurate simulation of the complex operation of the hydraulics in the area with, in particular, the presence of two distinct water tables. In addition, the conventional fauna/ flora inventories for operations of this type have been completed by the search for a compre-hensive ecological assessment, area by area.

3) Making meaningful use of stakeholders’ com-mitment to identify win/win opportunities. In 2008 and 2009, several consultation meetings were held to introduce the study process be-fore the public debate. The public debate was held from October 8, 2009 to February 7, 2010. It helped make significant progress to the project, as noted by Supervisory Board of the Grand Port Maritime du Havre in its decision of June 25, 2010 to pursue the studies of different alternatives.

It should be noted that the studies now include two new chapters directly resulting from the con-sultation:

• A study of the opportunities to decompartmen-talise the entire eastern part of the alluvial plain in order to make the wetlands more estuarine. The study clearly shows the need for shared choices in terms of the biological functionalities that should be given priority in the framework of the project, with particular respect to the Na-ture Reserve.

• A study to improve the circulation of water be-tween the North and South of the area. Under the cliff to the north, there are several natural springs, whose runoff is hampered by roads and the Tancarville Canal. The study highlighted the possibilities to restore freshwater runoff to the North of the Tancarville Canal, while the rele-vance of transferring them south of the Canal remains to be demonstrated.

These studies are therefore continuing as well as the consultation with, in particular, four workshops held in June 2011 followed by a public review meeting on July 5, 2011. Similarly, in late 2011, four workshops were held, attended each time by be-tween 30 and 50 participants, followed by a public meeting in January 2012 involving a hundred par-ticipants. The consultation continued throughout 2012 during the completion of the studies, which should facilitate the selection of a landscape scheme by the Supervisory Board of the GPMH.

4) Preparing complete project proposals/design that meet the needs of navigation and the en-vironment. Already, the use of the ‘Working with Nature’ process has enabled certain impacts to be avoided (such as the choice of vertical ca-nal banks to reduce land use and improve boat guidance), while eliminating others (such as the production a prototype side canal to recharge the groundwater table and suppress the drain-age effect caused by digging the canal) and reducing others (lowering the reference speed of trains to limit railway rights-of-way).

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For example, given the hydraulic studies and the consultations prior to the public debate, it was de-cided to add, alongside the new river canal on the Nature Reserve side, a side canal in which the water level will be maintained at a level such that there is no lowering of the water table due to the presence of the canal.

Following the public debate, it was decided to dig a life-size test side canal approximately 100 metres long. The chosen location is alongside the Tancarville Canal in order to demonstrate the ef-fectiveness of such a scheme in raising the aqui-fer. After a few difficulties involved in finding the

optimal level at which to dig the side canal, given the presence of impermeable land alongside the Tancarville Canal, the side canal demonstrated its effectiveness.

The project was presented as part of the new in-ternational ‘Working with Nature’ database and recognised by the jury consisting of members of all PIANC Commissions as being a ‘Candidate for a Certificate of Recognition’, thereby recognis-ing the application of the ‘Working with Nature’ philosophy in the different phases of the project already undertaken.

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This paper presents the PIANC ‘Working with Na-ture’ philosophy established in 2008 and revised in January 2011, which basically means doing things in a different order:

1) Establishing project needs and objectives2) Understanding the environment in the whole of

the project area3) Making meaningful use of stakeholders’ commit-

ments to identify possible win-win opportunities4) Preparing initial project proposals/design to ben-

efit navigation and nature

Furthermore, an operation is described carried out by the GPMH in the eastern part of the alluvial plain of the Seine Estuary, which is seen as a good illustration of this new philosophy.

This project, which is still in the study phase, is one of the first projects with ‘Candidate for a Certifi-cate of Recognition” status in the new PIANC inter-national ‘Working with Nature’ database.

SUMMARY

Le présent papier présente la philosophie de l’AIPCN ‘Œuvrer avec la Nature’, élaborée en 2008 et réactualisée en janvier 2011 qui peut se résumer en réaliser les projets dans un ordre dif-férent, à savoir:

1) Etablir les besoins et objectifs du projet2) Comprendre l’environnement dans la globalité

de la zone du projet3) Faire appel d’une manière constructive à

l’engagement des parties intéressées pour iden-tifier les opportunités de gagnant/gagnant

4) Préparer des propositions/conceptions initiales

pour le projet répondant aux besoins de la navi-gation et de l’environnement.

Est ensuite présentée une opération menée par le GPMH à l’Est de la plaine alluviale de l’Estuaire de la Seine qui paraît un bon exemple de l’utilisation de cette nouvelle philosophie.

Ce projet, encore en phase d’études, est l’un des tous premiers reconnus comme ‘candidat pour un certificat de reconnaissance’ dans la nouvelle base de données internationale de l’AIPCN ‘Work-ing with Nature’.

RESUME

Dieser Artikel präsentiert die PIANC ‚Working with Nature‘ Philosophie, die im Jahr 2008 aufgestellt und im Januar 2011 überarbeitet wurde; grund-sätzlich bedeutet sie, Dinge in einer bestimmten Reihenfolge zu tun:

1) Aufstellen der Projektanforderungen und -ziele2) Verstehen der Projektumgebung im Gesamt-

kontext3) Sinnvolle Nutzung des Engagements von Interes-

sensgruppen, um mögliche Win-Win-Situationen zu identifizieren

4) Vorbereitung der ersten Projektvorschläge/der

ersten Projektgestaltung unter Berücksichtigung der Bedürfnisse von Schifffahrt und Natur

Außerdem wird eine Maßnahme beschrieben, die von GPMH im östlichen Teil der Schwemmlande-bene an der Seine-Mündung durchgeführt wurde, welche als ein gutes Beispiel für die Anwendung dieser neue Philosophie angesehen wird.

Dieses Projekt, das sich noch in der Studienphase befindet, ist eines der ersten Projekte mit dem Sta-tus ‚Anwärter für ein Zertifikat‘ in der neuen interna-tionalen PIANC Datenbank ‚Working with Nature‘.

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