14 th European Seminar on Geography of Water

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14th European Seminar on Geography of WaterFacing climate change and desertification. Water Management in Sardinia

Drought Watch System in Sardinia to Reduce Supply Vulnerability and Improve Water Resources

Management During Periods of Drought

Roberto Silvano (Director of Water Resources Management and Remote Control Service - ENAS)

Ente Acque della Sardegna

ENASEnte Acque della Sardegna

Presented by: Andrea VirdisWater Resources Management and Remote Control Service

ENAS, Ente Acque della Sardegna, Italy

Water Resources management in Italy

2 Ente Acque della Sardegna

The management of the water resources in Italy and in the other Countries of the European Union underwent during the past years through significant changes

The EU Water Framework Directive (WFD) (2000/60/EC) is the major piece of European Union (EU) legislation having environment at its core. The Directive provides for a legislative framework aiming to protect Community waters in qualitative as well as in quantitative terms

What marks the Water Framework Directive out is that it defines the quality of surface waters in terms of ecology rather than chemistry or water pollution

Main aim of Member States is to restore the good ecological status (chemical, biological, hydromorphological) of ground and surface water in the framework of the river basin producing the River Basin Management Plan, in each river basin district

According to the devolution principle of the WFD, the environmental protection and monitoring, which was before a matter under the control of the Nation, fell on hands of the Regions by the mean of the Basin Authorities. These are Bodies created with the purpose of implementing, within their territory of competence, the Directive Rules

In 2006, the Italian Government started up the process wanted by the WFD by promulgating the Legislative Decree 152/2006 titled “Environment Policies” (“Norme in Materia Ambientale”), which reformed the entire body of environmental regulations in Italy

The Decree 152/2006 lists eight river basin districts in Italy. The districts are: Serchio, Padano, Eastern Alps, Northern Apennines, Central Apennines, Southern Apennines, Sardinia, and Sicily.

After the approval of the Legislative Decree 152/2006, the Sardinian Regional Authority reviewed competences and duties in the area of Water Resource, by means of the Regional Law 19/2006 “Rules on Water Resources and Hydrographic Basins” “Disposizioni in materia di risorse idriche e bacini idrografici”

Water Resources management in Sardinia Regional Law 19/2006


H y d r o e l e c t r i c I r r i g a t i o n D r i n k i n g w a t e r I n d u s t r i a l O t h e r U s e s

58%

25%

6%9%

2%

17%

37%33%

4%10%

I T A L Y S A R D I N I A

• In Sardinia, 80% of supplied water comes from artificial reservoirs (52 dams)• Main uses of dams in Sardinia are for irrigation and drinking water

purposes

The Regional law introduces the concept of “multi purpose water system”. This system is created to deliver raw water to different categories of users, contributing to keep a balance between supply’s quantity and costs

4

Sardinian Regional Authority

Regional Basin Authority

Institutional Committee

River Basin District Agency

Managing Body of the multi purpose water system: ENAS

Abbanoa S.p.A.Integrated urban water

Authority (ATO)

Reclamation Consortia Industrial Consortia

Institutional Flowchart of Sardinian Water System

Official assignment

Raw water supply

Official assignment

Regional Law n.19/2006

ENAS is the Region’s operational agency tasked with managing the island’s multi-purpose water system It supplies the wholesale water for the principal macro demands of the region civil, irrigational and industrial

... since 1946 EAF to-day ENAS ...

Regional Law n.19/2006 transformed EAF into ENAS

expanding and upgrading EAF by the addition of major water works for

multi-purposes uses and the experience and skills of staff coming from the Land Reclamation Consortia

At the same time, ENAS gave in to the Urban Water Service all the

waterworks for civil uses

Currently, the system comprises works and infra-structure for the

collection, storage and conveyance of raw water for multi-purposes

sectors

• 34 dams (1.900 Mmc of storage capacity)• 24 diversion dams, • 850 km of aqueducts, • 209 km of conveyance canals, • 47 pumping plants (with 70 Megawatt of

installed power)• 4 hydropower plants (13, 27.5, 1.3, 1.25

Megawatt)

ENAS - Ente Acque della Sardegna

ENAS – Distributed Volumes

CIVIL: to Abbanoa SpA, which is the Water Purification Company who is in charge of the Integrated urban water management in Sardinia

IRRIGATIONAL: to the nine Land Reclamation Consortia who have the management, at retail level, of raw water addressed to irriguous purposes

INDUSTRIAL: to five Industrial Consortia

In 2010 the following volumes were distributedSector Yearly distribution (million of mc) Water demand framework

Civil uses 221 1,5 million of inhabitant

Agricultural uses 327 160.000 equipped hectares

Industrial uses 27 11 industrial areas

TOTAL 575

Sardinia is located in the centre of the western basin of the Mediterranean Sea and has a surface area of 24.000 km² with a population of 1.648.000 residents

The climate is prevalently Mediterranean, characterized by a long period of drought in summer and mild and rainy winters with isolated frosts


The amount of water resources available for civil, industrial and agricultural use contracted critically in Sardinia about ten years ago due to hydrological alterations which had occurred on the island over the last three decades, similarly to the rest of the Mediterranean basin

Hydrological features and droughts in Sardinia

0

100

200

300

400

500

600

700

800

22-2

3

27-2

8

32-3

3

37-3

8

42-4

3

47-4

8

52-5

3

57-5

8

62-6

3

67-6

8

72-7

3

77-7

8

82-8

3

87-8

8

92-9

3

97-9

8

02-0

3

07-0

8

Run

off (

mill

ion

of m3 )

Hydrologic year

Annual runoff into the reservoirs of Medio Flumendosa

Yearly Runoff Moving Average 4 years Moving Average 7 years MeanMean 1922-1974 Mean 1975-2008 Mean 1986-2008

Mean water balance in Sardinia

1922-1975 Rainfall 775 mm Runoff 245 mm Runoff coefficient 0.32

1975-2005 Rainfall 620 mm Runoff 145 mm Runoff coefficient 0.23

Mean water balance in Sardinia

Analysis of the historical hydrological series in Sardinia over the past 90 years shows that both the rainfall and runoff are non-stationary in the mean


Hydrological features and droughts in Sardinia

The rainfall-runoff transformation in Sardinia proves that runoff is highly sensitive to any reduction in rainfall:

20% reduction in rainfall may produce a decrease of 40% in runoff and consequently in water resources available for human use.

Hydrological inflows display higher stochasticity and their behaviour is difficult to predict

Such variability, which is linked to the change in climatic conditions and has high repercussions on the volumes that can be supplied by water systems, and makes it necessary to manage resources using reliable and prudential operational rules

In this type of context, the management of complex interconnected hydraulic systems, mainly based on large reservoirs regulating the water resources over multiannual periods, plays a strategic role

A proactive action to be taken against droughts before they occur rather than simply reacting to them, must be the aim of the strategy

It is crucial to define criteria and operational rules to minimizing water supply deficits and to guarantee the sustainable use of natural runoff on a multi-annual base

The Region of Sardinia has in place since several years a drought alert and risk analysis system for the management of multi-purpose water supply systems, with the aim to reduce the vulnerability of supply and increase its reliability and avoid crisis situations


Drought Management System in Sardinia

Hydrological and Operational Droughts

Hydrological droughts: random natural phenomena, revealed by analysis of the historical hydrological data series

Operational droughts:lack of water supply available to users

Hydrological droughts are transformed into Operational droughts by a transformation function that considers the physical and size characteristics of the water work system and the operational rules selected to manage such waterworks

Drought is a phenomenon composed of both random natural aspects and important human component

It is therefore essential to build a model that accounts for all such aspects and delivers effective decision support


Drought indices

An indicator that takes into account these aspects is the amount of water reserves held in the artificial reservoirs of the regional water system

This parameter is influenced both by the characteristics of the hydrological inflows in the time and by the operational rules chosen to manage reservoirs and the main water conveyance lines

The built model accounts for all such aspects by implementing a calculation method that measure the indicator at monthly intervals, so to make decisions based on such measurements


The model: Methodology

This model, which is based on stochastic analysis principles, has two components:

- a model to generate synthetic series of the runoff of Sardinian rivers which preserves: a) the basic statistics of the historical series in each relevant section of rivers of the regional territory; b) the time correlation structure; c) the spatial correlation structure; d) specific drought statistics (persistence, duration, intensity);

- a simulation model for operating the water supply system using mathematical models to accurately represent both the functional characteristics of structural elements (reservoirs, pipes, open channels, pumping plant, hydroelectric plants, etc.) and the natural phenomena impacting the system, for instance evaporation from reservoirs and the operational rules adopted for optimum management of the resource

Using these two fundamental tools, a variable indicator is generated at monthly intervals for each reservoir or for two or more reservoirs forming a single water scheme


The output of the model is a state indicator which as an excellent key factor to measure the condition of water storage in the artificial reservoirs

It is named Storage Frequency Index: Index of the probability of not exceeding stored volumes, for each month of the year, in a single hydraulic system

It represents the indicator adopted for the drought management system in the region of Sardinia

This indicator summarizes both:- natural elements (rainfall reduction and, therefore, runoff which feeds artificial

water basins)- anthropic elements (the demand for water from basins, the rules governing

management of water resource transfer in complex hydraulic systems)


The model: Methodology

Application of the Drought Management System in SardiniaCurve of Storage Frequency Index

for each month of the year, in a single hydraulic system

0

200

400

600

800

1000

1200

O N D G F M A M G L A S

Wat

er S

tora

ge (m

illio

n m

3 )

Month

Tirso-Flumendosa system

0.9-1.00.8-0.90.7-0.80.6-0.70.5-0.60.4-0.50.3-0.40.2-0.30.1-0.20.0-0.1


Example: In April the probability of not exceeding a stored volume of 200 Mmc in the system is between 0.1 and 0.2 (high probability, 80-90% of exceeding)

Example: In April the probability of not exceeding a stored volume of 1100 Mmc in the system is 0.8 (low probability, 20%, of exceeding)

The value of the drought state indicator, at monthly scale, can be determined by matching the curves of the storage frequency index with the current water storage in each system


0

200

400

600

800

1000

1200

O N D G F M A M G L A S

Wat

er S

tora

ge (m

illio

n m

3 )

Month

Tirso-Flumendosa system

0.9-1.00.8-0.90.7-0.80.6-0.70.5-0.60.4-0.50.3-0.40.2-0.30.1-0.20.0-0.1

Example 1): In April if the current stored volume is 200 Mmc

The Storage Frequency Index is 0.1- 0.2 (that means that the model has forecast an high probability of exceeding 200 Mmc)

Consequently it is evident a critical state of the hydraulic system

Example 2): In April if the current stored volume is 1000 Mmc

The Storage Frequency Index is 0.5- 0.6 (that means that the model has forecast an low probability of exceeding 1000 Mmc)

Consequently it is evident a non critical state of the hydraulic system

Application of the Drought Management System in Sardinia

The values of the indicator have been grouped into four bands which, correspond to different state of the hydraulic system and consequently to different sets of decisions to be made and already identified in the water crisis management plan

These four bands represent the four rules defined to implement specific actions for an effective short-term drought mitigation measure


Storage Frequency Index Probability of not exceeding

Crisis level

0.50 - 1.00 ORDINARY REGIME (normal) 0.30 - 0.50 VIGILANCE (pre-alert) 0.15 - 0.30 DANGER (alert) 0 - 0.15 EMERGENCY

Definition of alert pointers

Application of the Drought Management System in Sardinia

Alert pointers and drought mitigation actions

Ordinary regime: for stored volumes in excess of the value that has a 50% probability of not exceeding;

Vigilance level: for stored volumes within the values having between 50% and 30% probability of not exceeding; It is necessary to monitor climate parameters to rapidly identify any further fluctuations which may reduce the mean resources available. Concurrently, consumption should be reduced to an amount that creates only limited discomfort for users

Danger level: for stored volumes between the values with non-exceeding probability of 30% to 15%. Water supply must be reduced to a substantial degree, in order to face the possible persistence of the dry period, and the planned mitigation measures must be implemented;

Emergency level: for stored volumes within 15% of the probability of not exceeding; This level should never be reached, since water supply should be restricted once the danger level is reached. However, should the emergency level be reached, this would mean that the statistical parameters of the series are continuing to change and therefore supply must be restricted further and the annual mean of water available for distribution must be reassessed.


Application of the Drought Management System in SardiniaSeries of the monthly drought indicator Storage Frequency Index

Monti Pranu

Tirso-Flumendosa System


Application of the Drought Management System in SardiniaDrought indicators of Sardinian Reservoir


Different characteristics of alert for the various water systems of the island

More uniform and with indicators that show a general situation of normality

June 2008 March 2010

RemarksThe application of this method to Sardinian water system, over about three years, has given good results to identify crisis areas and enforce mitigation measures

This method can be more finely tuned and perfected

As experience has shown, some aspects require particularly careful assessment and monitoring: it is preferable to anticipate shortages if the costs are not a linear function of the shortage; therefore it is

preferable to have several years with a moderate shortage rather than a single year with a high shortage;

measures to meet an anticipated shortage generate costs even though such shortage may not occur;

the timescale of such costs may cover several months or even years: this is a tough decision to make;

risk perception: it is not easy to measure. Different individuals and organizations have different perceptions: conflict situations;

it is essential to pursue a technically balanced solution and seek agreement among stakeholders.

The tool implemented, identifies and describes crisis areas and situations by means of easy-to-read quantitative parameters that represents a highly effective aid to public participation and stakeholder consultation processes


Thank you very much for you kind attention

ENTE ACQUE DELLA SARDEGNAVia Mameli, 88 - 09123 Cagliari

Tel +39 070 - 60 21.1Fax +39 070 – 670758

Water Resources Planning and Remote Control Service

(Servizio Programmazione e Telecontrollo)Ing. Roberto Silvano (Director)

Ing. Andrea Virdis

[email protected]@enas.sardegna.it

http://www.enas.sardegna.it

Documents

14 th European Seminar on Geography of Water