1 Senegal Report country wise

G l o b a l E n v i r o n m e n t F a c i l i t y

GEF MSP Sub-Saharan Africa Project (GF/6010-0016):

"Development and Protection of the Coastal andMarine Environment in Sub-Saharan Africa"

SENEGAL NATIONAL REPORT

PHASE 1: INTEGRATED PROBLEM ANALYSIS

Isabelle Niang-Diop (National Coordinator)Mamadou Dansokho, Ibrahima L.Y., Seydou Niang

March 2002

Disclaimer:

The content of this document represents the position of the authors and does not necessarily reflect theviews or official policies of the Government of Senegal, ACOPS, IOC/UNESCO or UNEP.

The components of the GEF MSP Sub-Saharan Africa Project (GF/6010-0016) "Development andProtection of the Coastal and Marine Environment in Sub-Saharan Africa" have been supported, incash and kind, by GEF, UNEP, IOC-UNESCO, the GPA Coordination Office and ACOPS. Supporthas also been received from the Governments of Canada, The Netherlands, Norway, United Kingdomand the USA, as well as the Governments of Cte d'Ivoire, the Gambia, Ghana, Kenya, Mauritius,Mozambique, Nigeria, Senegal, Seychelles, South Africa and Tanzania.

Table of ContentsPage

Executive Summary ................................................................................................................................. v

Senegal Country Profile ..........................................................................................................................iii

Chapter 11. The Importance of the Coastal Zone......................................................................................... 11.1 Biophysical Characteristics of the Coastal and Marine Zone................................................... 11.1.1 Morphology .............................................................................................................................. 11.1.2 Climate and Oceanography....................................................................................................... 11.1.3 Coastal Hydrodynamics............................................................................................................ 31.1.4 Coastal and Marine Biological Resources ................................................................................ 41.1.4.1 Coastal Ecosystems................................................................................................................... 41.1.4.2 Fish Resources .......................................................................................................................... 61.2 Socio-Economic Characteristics of the Coastal Zone............................................................... 61.2.1 Population ................................................................................................................................. 71.2.2 Economic Activities.................................................................................................................. 71.2.2.1 Fisheries .................................................................................................................................... 71.2.2.2 Tourism..................................................................................................................................... 81.2.2.3 Agriculture ................................................................................................................................ 9

Chapter 22. Process of Selection of Hot Spots and Sensitive Areas and Identification of Major Environmental Issues .............................................................................................................. 102.1 Hot Spots................................................................................................................................. 102.1.1 The Djoudj Bird National Park............................................................................................... 102.1.2 The Hann Bay ......................................................................................................................... 122.1.3 Djiffere.................................................................................................................................... 132.2 Sensitive Areas ....................................................................................................................... 132.2.1 The Sngal Delta................................................................................................................... 152.2.2 The Saloum Estuary................................................................................................................ 172.2.3 The Casamance Estuary.......................................................................................................... 18

Chapter 33. Impacts of the Main Environmental Issues in Senegal........................................................... 203.1 Issue 1: Modification of Stream Flows................................................................................... 203.1.1 Reduction of Stream Flows: Constitution of Inverse Estuaries.............................................. 203.1.1.1 Description.............................................................................................................................. 203.1.1.2 Environmental Impacts ........................................................................................................... 233.1.1.3 Socio-Economic Impacts ........................................................................................................ 283.1.2 Reduction of Sea Water Intrusion/Permanence of Freshwaters due to Dam Construction .... 283.1.2.1 Environmental Impacts ........................................................................................................... 283.1.2.2 Socio-Economic Impacts ........................................................................................................ 303.2 Issue 12-13: Modification/Destruction of Ecosystems........................................................... 313.2.1 Mangrove Ecosystem.............................................................................................................. 313.2.2 Sandy Beaches ........................................................................................................................ 323.2.2.1 Environmental Impacts ........................................................................................................... 323.2.2.2 Socio-Economic Impacts ........................................................................................................ 323.3 Issue 6: Chemical Pollution .................................................................................................... 323.3.1 Description.............................................................................................................................. 333.3.2 Environmental Impacts ........................................................................................................... 343.3.2.1 Water Quality.......................................................................................................................... 343.3.2.2 Fishes ...................................................................................................................................... 34

3.3.3 Socio-Economic Impacts ........................................................................................................ 353.4 Socio-Economic Impacts Obtained with the Giwa Scoring Methodology............................. 36

Chapter 44. Causal Chain Analysis ............................................................................................................ 404.1 Issue 1: Modification of Stream Flows................................................................................... 404.1.1 Sngal River.......................................................................................................................... 404.1.1.1 Immediate Causes ................................................................................................................... 404.1.1.2 Sectoral Causes ....................................................................................................................... 404.1.1.3 Responses................................................................................................................................ 424.1.1.4 Transboundarity Issues ........................................................................................................... 434.1.2 Saloum and Casamance Estuaries........................................................................................... 434.1.2.1 Responses................................................................................................................................ 434.1.2.2 Transboundarity Issues ........................................................................................................... 434.2 Issue 12-13: Modification/Destruction of Ecosystems........................................................... 434.2.1 Fish Communities ................................................................................................................... 434.2.1.1 Immediate Causes ................................................................................................................... 444.2.1.2 Sectoral Causes ....................................................................................................................... 474.2.1.3 Responses................................................................................................................................ 484.2.1.4 Transboundarity Issues ........................................................................................................... 494.2.2 Mangrove and Wetlands Ecosystems ..................................................................................... 494.2.2.1 Immediate Causes ................................................................................................................... 494.2.2.2 Sectoral Causes ....................................................................................................................... 504.2.2.3 Responses................................................................................................................................ 504.2.2.4 Transboundarity Issues ........................................................................................................... 514.3 Issue 6: Chemical Pollution .................................................................................................... 524.3.1 Immediate Causes ................................................................................................................... 524.3.2 Sectoral Causes ....................................................................................................................... 524.3.2.1 The Industry Sector................................................................................................................. 534.3.2.2 The Petroleum Sector.............................................................................................................. 544.3.3 Responses................................................................................................................................ 544.3.3.1 Governmental Responses........................................................................................................ 544.3.3.2 Community Responses ........................................................................................................... 544.3.3.3 Market Responses ................................................................................................................... 554.3.4 Transboundarity Issues ........................................................................................................... 564.4 Root Causes ............................................................................................................................ 564.4.1 Social Changes........................................................................................................................ 564.4.1.1 Demographic Growth and Urbanization................................................................................. 564.4.1.2 Poverty .................................................................................................................................... 564.4.2 Institutional Drivers ................................................................................................................ 574.4.2.1 Limits of the Decentralization Process ................................................................................... 574.4.2.2 Weakness of Existing Legal Instruments................................................................................ 574.4.3 Economic Structure................................................................................................................. 574.4.3.1 State of the National Economy ............................................................................................... 584.4.3.2 Sectoral Policies...................................................................................................................... 58

Chapter 55. Recommendations................................................................................................................... 59

References .............................................................................................................................................. 60

Annex I Fiche Didentification: Points Chauds, Zones Sensibles Et/Ou Probleme Primordial ........... 71

List of Figures and Tables

Figure 1 The Different Types of Coasts in Senegal .............................................................................. 2Figure 2 Migration of the Isohyets Between 1931-1960 and 1961-1990 ............................................. 3Figure 3 The "Niaye" Vegetation.......................................................................................................... 6Figure 4 Vegetation Repartition in the Mangrove: Case of the Saloum Estuary.................................. 6Figure 5 Hot Spots and Sensitive Areas Selected ...................................................................................Figure 6 The Djoudj Bird National Park............................................................................................. 11Figure 7 Exit of One of the Canals in the Hann Bay Beach ............................................................... 13Figure 8 Evolution of the Sangomar Sand Spit between 1986 and 1993............................................ 14Figure 9 The Sngal "Delta".............................................................................................................. 16Figure 10 The Saloum Estuary.............................................................................................................. 17Figure 11 The Casamance Estuary........................................................................................................ 19Figure 12 Tidal Current Velocities and Tidal Range Evolution in the Saloum River in Front

of Djiffere (20 April 1982) ................................................................................................... 22Figure 13 Evolution of the Minima and Maxima of Salinity in the Saloum River between 1928

and 1993................................................................................................................................ 23Figure 14 Evolution of the Mangrove Ecosystem in the Saloum Estuary ............................................ 26Figure 15 Evolution of Some Characteristics of the Casamance Estuary Between its Mouth and

About 250km Upstream........................................................................................................ 27Figure 16 Guiers Lake Level Before and After the Diama Dam .......................................................... 30Figure 17 Causal Chain Analysis for Modification of Stream Flow: The Sngal River..................... 41Figure 18 Causal Chain Analysis for the Modification of Ecosystems: Fish Communities in the

Hann Bay .............................................................................................................................. 44Figure 19 Causal Chain Analysis for Modification of Ecosystems: Fish Communities in the

Sngal Estuary .................................................................................................................... 45Figure 20 Causal Chain Analysis for the Modification of Ecosystems: Fish Communities in

the Saloum and Casamance Estuaries................................................................................... 46Figure 21 Causal Chain Analysis of the Modification of Ecosystems: Fish Communities on

the Southern Continental Shelf ............................................................................................. 46Figure 22 Causal Chain Analysis for Modification of Mangroves and Wetlands ................................ 49Figure 23 Causal Chain Analysis for Chemical Pollution .................................................................... 53

Table 1 Main Characteristics of the Littoral Climatic Zones (1961-1990 Period).............................. 3Table 2 Deep Sea Characteristics of the Main Types of Swells Along the Senegalese Coastlines .... 4Table 3 Population Repartition by Administrative Region in 1999 .................................................... 7Table 4 Synthetic Table for Hot Spots...................................................................................................Table 5 Synthetic Table for Sensitive Areas..........................................................................................Table 6 Synthetic Table for Hot Spots...................................................................................................Table 7 Synthetic Table for the Selection of Environmental Issues......................................................Table 8 Climatic Rupture of Some Littoral Stations ......................................................................... 20Table 9 Evolution of Annual Rainfall in the Saloum Basin .............................................................. 21Table 10 Fluvial Discharge Evolution in Some Estuaries ................................................................... 21Table 11 Types of Polluted Products Entering in the Hann Bay ......................................................... 33Table 12 Pollutants Entering in the Hann Bay from Diverse Economic Activities ............................ 34Table 13 Socio-Economic Scores as Deduced from GIWA Methodology: Hot Spots ....................... 38Table 14 Socio-Economic Scores as Deduced from GIWA Methodology: Sensitive Areas .............. 39Table 15 Evolution of Fish Exportations Between 1992 and 1997 ..................................................... 48Table 16 Comparaison of Industrial and Domestic Sewages Composition......................................... 52

iExecutive Summary

The importance of coastal and marine zones for a country like Senegal can easily been deduced fromthe following numbers: 700 km of coastline, concentrating more than 50% of the population and 85%of the industries and services, two economic activities being the first sources of earnings (fisheries andtourism) but as the same time depending on marine (fish) and coastal (beaches) resources.

Based on the identification of hot spots and sensitive areas, the three main environmental problemsrelative to coastal and marine environments were, by priority order: modification of stream flows,modification/destruction of ecosystems and chemical pollution. Due to its geographical position (in asemi-arid area), Senegal is extremely sensitive to the diminution of precipitations registered since theyears 1970. Two types of modifications of stream flows were observed: the transformation of estuariesin reverse estuaries with salinity increasing upstream (Saloum and Casamance) and the artificializationof the Senegal estuary due to damming which induced a separation between a completely salineestuary downstream of the dam and an upstream part with only freshwaters. Modification andsometimes destruction of ecosystems is the second major problem in the coastal and marine zones. Areconcerned the fish communities but also the mangroves, wetlands and beaches. Finally, chemicalpollution is a problem mainly associated with urbanized coastal zones, the Hann bay being a goodexample of this issue.

The impact analysis identified different environmental and socio-economic consequences of the 3environmental issues identified. The main consequences of the modification of stream flows, in thecase of reverse estuaries, have been a salinisation of soils and waters (included aquifers) and importantchanges in the flora (mainly mangroves) and fauna (fish in particular) living in and around the rivers.This induced problems of availability of water and soils mainly for peasants as well as a diminution offisheries. However, salt production increased. In the Senegal estuary, that has been affected by theanti-salt Diama dam, the downstream part of the river was submitted to similar consequences as theprevious rivers together with morphological changes due to the dominance of sea dynamics(southwards growth of the sand spit and development of a mouth bar) while the upstream partexperienced invasion by macrophytes (mainly Pistia spp. and Salvinia molesta), modifications of thefish communities and the development of vectors of parasitoses (mainly Bulinus guernei andAnophelus spp.). These environmental modifications induced navigation problems mainly at themouth and the development of the bilharsiosis and malaria in the upper delta. However due to thedam, more water is now available for irrigated agriculture and drinking water.

The modification/destruction of ecosystems was mainly analyzed for mangroves and beaches. Themain consequences of the breaching of the Sangomar sand spit close to Djiffere was a severe coastalerosion that induced a destruction of infrastructures (i.e. fishery factory and tourist camp)accompanied by accumulation processes responsible for the death of part of the mangrove as well asdifficulties of navigation and communication with some villages.

The chemical pollution exemplified by the Hann bay has induced a deterioration of water quality, theproliferation of algae as well as deep modifications and also contamination of the fish communities inthe bay. This in turn determined a deterioration of the human health, the impossibility for differentusers to use the seawater and also difficulties for fishermen that not only need to fish further offshorebut also face difficulties to sell their fish.

Causal chain analysis was conducted for each of the environmental issues. Immediate causes arevariable depending on the environmental issue considered. They can be natural: impacts of the droughton the river systems, destruction of mangroves on the fish communities. But most of the time they areanthropic: damming of the rivers (modification of stream flows), over-exploitation (modifications offish communities and also of mangroves), discharge of untreated sewage (chemical pollution). It wasalso evidenced that some environmental issues can be the immediate cause of other issues: forexample, destruction of mangroves is partly linked to the modification of stream flows.

ii

At a sectoral level, the main sectors involved are agriculture, industry, water supply, fishery andenergy. Most of them are the basis of the main needs of the population (land and water availability,food and energy demand) and it is because they try to respond to these needs that they inducedenvironmental problems. The case of industry is a little bit different since this sector doesnt intervenein the satisfaction of the basic needs of the population. This again confirms the high dependence of thecountry to its natural resources. It is important to notice that the implication of the fishery sector isalso closely linked to the necessity to develop exports indicating a strong pressure of the internationalmarket.

At a root level, the same global causes are concerned, mainly the demographic growth, theurbanization but strongly coupled with poverty. At an institutional level, what is still predominant isthe lack of coordination between environmental and sectoral policies in a context wheredecentralization is not fully achieved. Another aspect is the weakness in the implementation of thelaws. The third main group of root causes is relative to the weakness of the national economy, withlow growth rates and the constraint of the debt leading to the development of a strategy ofexportations. The cohabitation of sectoral policies with environmental policies doesnt allow for a truesustainable development strategy.

Elements of transboundarity are present for almost all the environmental problems examined. TheSenegal river has a status of international river managed with a sub-regional organization. Someecosystems and particularly those located in protected areas have borders with the neighbouringcountries (Djoudj Park with Mauritania, Saloum delta park with The Gambia) and bilateral agreementsare already taking place. Some resources, like fish, ignore the boundaries and belong to regionalstocks. The only hot spot that doesnt present transboundary aspects is the Hann bay. However, it is agood example of the degradation of most of the big coastal cities in sub-Saharan Africa. As such, itmust be considered one of the models of coastal pollution that is a common problem in the entireregion.

iii

SENEGAL COUNTRY PROFILE

Geography and EnvironmentSurface area: total:Coastline:Maritime claims: continental shelf:

exclusive economic zone (distance fromshore):

territorial sea:EEZ:Natural resources:Land use: arable land:

permanent crops:permanent pastures:

forests and woodland:other:

Irrigated land:Environment - international agreements:party to:

signed, but not ratified:

196,190 sq km700 km200 NM or to the edge of the continental margin

200 NM12 NM147,200 km2

Fish, phosphates, iron ore12%0%16%54%18% (1993 est.)710 sq km (1993 est.)Biodiversity, Climate Change, Desertification,Endangered Species, Hazardous Wastes, Law of the Sea,Marine Life Conservation, Nuclear Test Ban, OzoneLayer Protection, Ship Pollution, Wetlands, WhalingMarine Dumping

PopulationPopulation:Population growth rate:Population density in the coastal zone:Life expectancy: total population:Urban population (% of total 1995):Urban population annual growth rate:

10,284,929 (July 2001 est.)2.93% (2001 est.)19-4081 hab/km2

62.56 years43.73.88% (rate 1995-2015)

1 Which accounts for around 19% of total land area

iv

Population living within 100 km from thecoast:Population living in coastal districts1

Literacy:(definition: age 15 and over can readand write)

83.2%54% (1996)Total population: 33.1%Male: 43%Female: 23.2% (1995 est.)

EconomyGDP: purchasing power parityGDP - real growth rate:GDP per capita: purchasing power parityGDP composition by sector:

agriculture, forestry and fisheries:industry: services:

Labour force - by occupation:Industries:

Industrial production growth rate:Electricity - production:Electricity - production by source:Electricity - consumption:Electricity - exports:Electricity - imports:Agriculture - products:

Exports:Exports - commodities:

Imports:Imports - commodities:

Currency code:Exchange rates:

$16 billion (2000 est.)5.7% (2000 est.)$1,600 (2000 est.)

19% (includes 2.6% from fisheries)20%61% (3% includes from tourism) (1997 est.)Agriculture 60%Agricultural and fish processing, phosphate mining,fertilizer production, petroleum refining, constructionmaterials7% (1998 est.)1.27 billion kWh (1999)Fossil fuel: 100%1.181 billion kWh (1999)0 kWh (1999)0 kWh (1999)Agriculture - products: peanuts, millet, corn, sorghum,rice, cotton, tomatoes, green vegetables; cattle, poultry,pigs; fish$959 million (f.o.b., 2000)Fish, ground nuts (peanuts), petroleum products,phosphates, cotton$1.3 billion (f.o.b., 2000)Foods and beverages, consumer goods, capital goods,petroleum productsCommunaute Financiere Africaine franc (XOF);XOF per US dollar - 751.641 (January 2002), 699.21(2001), 711.98 (2000), 615.70 (1999), 589.95 (1998),583.67 (1997), 511.55 (1966)

Water Resources and UsesInternal flowsFlows from other countriesTotal resources per capita cu. m3:Annual freshwater withdrawals:

% of total renewable resources:% for agriculture:

% for industry:% for domestic:

26 billion cu. m. 199913.0 billion cu. m. 19994,2431.5 billion cu. m.3.89235

Chapter 1

1. The Importance of the Coastal Zone

With about 700 km of coastline (Diaw, 1984), Senegal is extremely dependent on its coastal andmarine zones. Not only important highly productive ecosystems are present (mangroves, "niayes") butalso population as well as major economic activities is also located close to the sea. Fisheries andtourism that are the two main sources of earnings in Senegal are economic activities linked to thecoastal and marine zone.

1.1 Biophysical Characteristics of the Coastal and Marine Zone

1.1.1 Morphology

The morphology of the coasts is relatively simple with three main types of coasts (Figure 1):

rocky coasts that are limited to the Cap Vert peninsula and some sectors on the south ofDakar and in Casamance. They are characterized by cliffs made of diverse types of rocks:basaltes, dolerites, siltites, limestones, sandstones sometimes capped with laterite;

sandy coasts that belong to 2 types: north of the Cap Vert peninsula is the "Grande Cte",rectilinear, where beaches are part of a wide dune system while south of the peninsula is the"Petite Cte" constituted of a succession of capes and bay beaches. Here, beaches are backedby a single barrier sometimes limiting small lagoons; and

estuaries with mangroves the most important being, from North to South, the Senegal"delta", Saloum and Casamance estuaries. These estuaries are bordered by sand spits andpresent immense flat areas partially colonized by mangrove.

These coasts are bordered by a continental shelf whose width doesn't exceed 100 km, being thenarrower (2-15 km) around the Cap Vert peninsula (Meagher et al., 1977; Ruffman et al., 1977). Themain feature is the presence of the Kayar canyon - one of the main submarine canyon along theAfrican Atlantic coast - that is supposed to trap part of the N-S longshore transport, generating asediment starvation of the south coast (Dietz et al., 1968; Ruffman et al., 1977).

1.1.2 Climate and Oceanography

The Senegalese climate is characterized by two seasons determined by the latitudinal migration of theIntertropical Convergence Zone (ITCZ): a dry season between November and June and a rainy seasonbetween July and October. The coastal zone is influenced by the Atlantic Ocean and belongs to 3 mainlittoral climatic zones: the "Grande Cte" zone, from Saint-Louis to Dakar; the "Petite Cte" andSaloum zone, from Dakar to the Saloum estuary; then the Low Casamance along the Casamanceestuary (Malou et al., 1998). Main climatic parameters of these different zones are presented in Table1.

The recent evolution of the climate is marked by a rupture that occurred between 1966 and 1970 and ischaracterized by a diminution of precipitations varying between 20 and 40% and determining asouthwards migration of the isohyets (Figure 2) (Malou et al., 1998).

The main characteristic of the oceanic circulation is the development of seasonal upwellings inducedby NE trade winds. Beginning in November January, upwellings first are located along the north coastwhere they are coastal, being at their maximum between February and April. On the south coast, themaximum of upwelling occurs between February and May but here they are located along the 70 to100 m isobaths. The Cap Vert peninsula as well as the Kayar region is zones of convergence thatinhibit the development of upwellings. The intensity of upwellings varies from year to year (Roy,1989).

Senegal National Report 040302.

Page 2 of 76

Figure 1: The Different Types of Coasts in Senegal (from Sall, 1982)


Page 3 of 76

Table 1. Main Characteristics of the Littoral Climatic Zones (1961-1990 Period)(from Malou Et al., 1998)

Mean AnnualRainfall

Mean AnnualTemperatures

Mean AnnualHumidity

"Grande Cte" zoneSaint-Louis (1603'N, 1627'W)Dakar (1444'N, 1730'W)

265.2 mm413.5 mm

27.5C25C

64.8%75.9%

"Petite Cte" and Saloum zoneKaolack (1408'N, 1604'W) 607.2 mm 28.6C 55.4%Low Casamance zoneZiguinchor (1233'N, 1616'W) 1,251.9 mm 27.2C 67.4%

Figure 2. Migration of the Isohyets Between 1931-1960 and 1961-1990(from Malou et al., 1998)

1.1.3 Coastal Hydrodynamics


Page 4 of 76

Two main types of swells affect the Senegalese coastlines: NW swells that particularly impact theNorth coast while they are attenuated along the south coast due to the diffractions around differentpoints of the Cap Vert peninsula (Riffault, 1980); SW swells that mainly concern the south coastduring the rainy season (July to October). Although rare, W swells are very energetic. The maincharacteristics of these swells are indicated in Table 2.

Table 2. Deep Sea Characteristics of the Main Types of Swells Along the Senegalese Coastlines(from Nardari, 1993)

Types of swells Mean period Mean height Mean wavelengthPower before

breakingNW 6.3 s 1.67 m 62 m 18 kW.m-1

SW 5.7 s 1.49 m 51 m 11 kW.m-1

W 6.8 s 1.80 m 73 m 22.7 kW.m-1

Due to the fact that the swells are mostly oblique to the coast, they are responsible for general N-S toNW-SE longshore currents. Those currents are feeding and maintaining the main sand spits borderingrivers and lagoons. Estimations of the littoral drift indicate a strong difference between the North andSouth coasts: 200,000 to 1,500,000 m3.y-1 along the North coast against 10,500 to 30,000 m3.y-1 alongthe beginning of the South coast (Barusseau, 1980; Sall, 1982) and 100,000 to 300,000 m3.y-1 alongthe Sangomar sand spit (Lefur, 1950; Pelnard-Considere, 1959; Diaw et al., 1991).

Tides are semi-diurnal with a tidal range varying between 0.5 m for neap tides and 1.6 m for springtides. Tidal currents are thus very weak (speeds less than 0.15 m.s-1; Domain, 1976; Rebert, 1983).except in the river mouths. The sea level presents mean seasonal variations of 20 cm that seem to belinked with upwellings (Niang-Diop, 1995a).

The Dakar tide gauge record (between 1943 and 1965) indicates a mean sea-level rise of 1.4 mm.y-1

(Elouard et al., 1977).

1.1.4 Coastal and Marine Biological Resources

Some important economic activities are based on biological resources present in the coastal zone, inthe estuaries or in the continental shelf waters. The main resources are constituted by coastalecosystems and fish communities.

1.1.4.1 Coastal Ecosystems

Two main ecosystems are located along the coasts: "niayes" and mangroves.

"Niayes" are interdune lows where coastal aquifers are outcropping. This allowed the installation of arelict vegetation belonging to the Guinean zone (Trochain, 1940; Michel et al., 1969) andcharacterized by species like oil palm (Elaeis guineensis) accompanied by ferns (Cyclosurusproliferus, C. striatus, Lygodium microphyllum) (Figure. 3). Peats accumulated here since thousand ofyears (Pezeril et al., 1986). Located all along the North coast, the "niayes" are used for marketgardening (Ndiaye A.L., 1995). Actually they are endangered by the drought leading to a lowering ofthe water table and stress on the vegetation as well as by the inwards migration of littoral dunes.


Page 5 of 76

Figure 3. The "Niaye" Vegetation (from Michel et al., 1969)

Mangroves are well known as a high productive ecosystem all around the world. The particularity ofthe Senegalese mangroves is that they are, together with those of Mauritania (Arguin bank and Tidraisland at about 1440N), the northernmost mangroves encountered on the west coast of Africa.Measurements made in the Sine Saloum estuary gave a biomass productivity of 1.8 to 2.1 tons perhectare and per year, which is relatively low compared to other mangroves in the world (Agbogba etal., 1984). The total area covered by mangroves in Senegal in 1990 has been estimated at about300,000 ha with 80,000 ha in Saloum estuary and 250,000 ha in Casamance (Diop and Ba, 1993).

The Senegalese mangrove is constituted of six species belonging to three families: the Rhizophoracaeawith Rhizophora racemosa, R. mangle and R. harrisonii (more extended but shorter); the Verbenacaeawith Avicennia africana or nitida (Sow et al., 1994); and the Combretacaea represented byConocarpus erectus and Laguncularia racemosa. The current distribution of these species from theriverside to the interior of islands is as follows (Diop, 1986; Figure 4):

after the intertidal marshes, the first species that colonize the thick clayey soils areRhizophora racemosa and R. mangle, relatively high (up to 20 m) that constitute what iscalled the high mangrove. This external part of the mangrove traps the sediments andconstitutes a shelter against wave attack;

then comes Avicennia africana, which prefers the shallow clayey soils, less inundated butmore salted. This species can be accompanied by other trees like Laguncularia racemosaand Conocarpus erectus constituting a low mangrove. Under Avicennia, is present a carpetof Sesuvium portulacastrum accompanied with Paspalum vaginatum; and

behind are bare areas called "tannes" then herbaceous areas called lawns (Diaw et al., 1993)that are colonized by halophyte species (Diaw and Thiam, 1993) but also by trees likeTamarix senegalensis, Adansonia digitata and other species like Andropogon gayanus,Sporobolus robustus and Sphaeranthus senegalensis.


Page 5 of 76

Figure 4. Vegetation Repartition in the Mangrove: Case of the Saloum Estuary(from Diop and Ba, 1993)

Not only mangroves are important nursery and reproductive grounds (Diouf, 1996), they are alsointensively used by the populations: collection of shellfish, leaves and fruits for food, wood forcooking and building (Ndiaye, V., 1995). It is also a major attraction for tourists.

1.1.4.2 Fish Resources

There are classified in four groups: coastal pelagic, coastal demersal, offshore pelagic and estuarineresources. The first 3 groups depend mainly on the upwellings while the last one benefit from thesituation of reverse estuaries where waters are slowly expulsed to the sea, estuaries benefiting thusfrom trophic enrichment (Diouf, 1996).

Coastal pelagic are the main fish resources in Senegal (75% of the landings). About 80% areconstituted of sardines (Sardinella aurita and S. maderensis). In 1990 the potential exploitable stockswere estimated at 20,000 tonnes for the "Grande Cte", 130,000 tonnes for the "Petite Cte" and40,000 to 60,000 tonnes for Casamance (Barry-Grard et al., 1993).

Coastal demersal resources (between 0 and 200 m) include shell fish (shrimps, lobsters, crabs, ),cephalopods (octopus, ) and fishes (soles, groupers, ). They have a high commercial value and aremore and more exported. The potential was estimated at about 100,000 tonnes (Barry-Grard et al.,1993). Indices of over-exploitation have been found for depths less than 60 m especially on the SouthCoast.

Offshore pelagic resources are mainly constituted of thunidae, mainly albacore (Thunnus alalunga),bigeye tuna (Thunnus obesus) yellowfine tuna (Thunnus albacares) and Skipjack tuna (Katsuwonuspelamis). They are mainly exploited by industrial fisheries and can determine conflicts betweenartisanal and industrial fisheries but also with neighbouring fisheries (Le Reste, 1993).

Estuarine resources are mainly constituted of fishes (about 250 species), shrimps (4 species) andmolluscs (oysters, Anadara senilis, Cymbium, Murex sp.). Annually 30,000 to 50,000 tonnes of fishescome from estuaries while the shrimp production is of about 350 tonnes annually in the Saloum and800 to 1,600 tonnes in Casamance.

1.2 Socio-Economic Characteristics of the Coastal Zone


Page 5 of 76

1.2.1 Population

Senegal is divided in two geographical areas unequally populated, urbanized, equipped and developed:the western part open on the littoral, more urbanized, and the eastern and central part, more rural.

The World Bank estimated that in 1994 about 4.37 million of people lived in the coastal zone (definedas the 60 km wide land band along the shoreline and covering 17.7% of the total area) representingabout 54% of the total population (World Bank, 1996). A quick glance on the Table 3 shows a greatdisparity even in the coastal regions. The Dakar region housing the capital concentrates 24% of thetotal population, 85% of the industries and services in an area that represents only 0.28% of the totalarea.

Table 3. Population Repartition by Administrative Region in 1999(from Rpublique du Sngal, 1993)

Regions PopulationPercent of the Total

PopulationDensity

Saint-Louis 826,343 9 19Louga 550,585 6 19This 1,276,286 14 193

Diourbel 875,272 9 195Dakar 2,244,682 24 4081Fatick 618,837 7 78

Kaolack 1,074,178 12 67Ziguinchor 530,393 6 72

Kolda 778,283 8 37Tambacounda 505,924 5 8

SENEGAL 9,280,783 100

(Lines in grey represent regions with coastal zone).

Moreover, the littoral zone concentrates the urban population of the country. The big towns (Dakar,Saint-Louis, Mboro, Rufisque, Mbour, Kaolack, Joal, Ziguinchor) are located in the coastal zone(Niang-Diop, 1995b). This concentration of population along the coastal zone is one of the reasons ofthe pollution problems encountered almost in all these towns.

These trends are supposed to continue and even accelerate over the next years.

1.2.2 Economic Activities

In 1992, the active population in the coastal zone was estimated to be 1,185,666 people, representingabout 43% of the total. In 1992, the coastal zone contributed for about 68% of the GDP indicating itscrucial importance for the country. Many infrastructures (roads, harbours, airports) are located alongthe coastal zone.The main activities linked strictly to the coastal and marine zone are: fisheries, tourism and someagricultural activities (market gardening and rice growing).

1.2.2.1 Fisheries

Mainly artisanal, fishery is the main activity for 65,000 fishermen but generates more than 220,000indirect employment. Thus it employs about 15% of the total active population (Devey, 1997). Theannual fish production is around 400,000 tonnes, mainly from the artisanal fisheries (78%). Artisanalfisheries were represented by about 10,000 boats in 1995. The main landing points are Saint-Louis,Kayar, Dakar, Mbour, Joal, Kafountine and Cap Skirring (Dione, 1986). Industrial fisheries represent


Page 5 of 76

about 130,000 tonnes of fish, 90% being exported. Tuna production itself represents about 36,000tonnes.

30 to 40% of the production is transformed artisanally, mainly by women. Fish and shellfish aresmoked, grilled and dried. These transformed products are mainly consumed in Sngal (57%), therest being exported essentially in West Africa. However, the quality of the products is not always goodenough and also this activity generates a lot of pollution of the beaches (Gueye-Ndiaye, 1993).

About 70 factories, mainly located in Dakar and Ziguinchor, are specialized in the transformation ofsea products mainly for exportation. It was estimated that 70% of the exports were constituted offrozen fish, the rest being mainly canned tuna and fish flour (Devey, 1997). The main destinations forthe exportations are Europe (53%) and Africa (39%).

Since 1986, fisheries represent the first source of foreign currencies before tourism. Between 1994(year of the devaluation) and 1997, the market value of halieutic production grown from 35.2 to 42billion of CFA Franc and actually represents 2.6% of the GDP and 11% of the primary sector GDP.Between 1991 and 1996, the value of halieutic production exports rose from 61 to 160 billion of CFAfrancs. This is mainly due to the devaluation that favour exports. Meanwhile, this induces difficultiesfor the population to find fish that covered about 75% of the protein needs. Moreover, fisheriesgenerate fiscal entries of about 10 billion of CFA francs (fish licenses, taxes and penalties) and the lastfishing agreement between Senegal and the European Union (1997-2001) represented an amount of31.5 billion CFA F for the Government.

1.2.2.2 Tourism

Well developed in Dakar (37% of the tourist accommodation) and also along the South Coast (24% ofthe accommodation) and in Casamance (23%), it is mainly tourism for foreigners with big touristcompanies involved. Two main tourist complexes are present along the coast: the Saly complex (onthe South Coast just north of Mbour) with about 10 hotels (about 1,740 beds) in an area of 970 ha andthe Cap Skirring complex (Casamance) with about 10 hotels stretching along 4 km of coast (SeneDiouf, 1993). However, there is also a development of medium to low standing tourist infrastructuresmainly by villages and the private sector. Second economic activity (78.7 billion CFA francs in 1995),tourism contributes for about 3% to the GDP. The jobs generated are about 26,000, 15,000 beingseasonal.

This sector is growing constantly. Between 1972 and 1996 the number of foreign tourists raised from255,787 to 1,127,067 representing an evolution in the receipts from 2 to 78.7 billion of CFA F. Thedevaluation in 1994 induced a doubling of the receipts (27 billion in 1993 and 55 billion in 1994)(Devey, 1997).

There is a strategic plan for the development of tourism that anticipates the reception of 1.5 million oftourists by the year 2010.


Page 5 of 76

1.2.2.3 Agriculture

Market gardening is usually developed in the "niayes" with an annual production of about 155,000tonnes, 36.5% coming from the Thies region and 27.7% from the Dakar region. The "niayes"ecoregion is the second region for the production of fruits. Till now this activity is not well organizedwith a lot of problems for the transport of fruits and vegetables (Devey, 1997).

Rice growing is practiced mainly in the estuaries, especially in Casamance (pluvial growingrepresenting about 20% of the areas cultivated) and in the Senegal valley (irrigated growing).However this activity is facing problems like soil salinisation in the southern estuaries and theconcurrency with imported rice. In Casamance a shift of the rice fields from the river borders to theplateau has been observed due to soil salinisation (cf Cormier-Salem, 1994).


Page 5 of 76

CHAPTER 2

2. Process of Selection of Hot Spots and Sensitive Areas and Identification ofMajor Environmental Issues

2.1 Hot spots

The three hot spots that have been selected belong to three different parts of the country (see Figure 5)with, from north to south: the Djoudj bird National Park which is located in the north-western part ofthe Senegal delta; the Hann bay located just south east of the capital, Dakar, in the western central partof the country and Djiffere located on the Sangomar spit that limits the Saloum river.

2.1.1 The Djoudj Bird National Park

Located between 1630'N and 1610'W, at about 60 km northwest of Saint-Louis, the Djoudj BirdNational Park belongs to the Sngal delta. Created in 1971 (decree 71.411 completed by decree75.1222 of the 10th of December 1975), it covers an area of 160 km2 and is situated between theSenegal River and the Djeuss. It is composed of three lakes (Lamantin lake 1000 ha, Grand Lake,5500 ha and Khar Lake, 1500 ha) that are linked with the Senegal through a number of small rivers themain being the Djoudj to the north and the Gorom to the south, the Crocodile canal, between theSenegal river and the Lamantin lake being used to inundate the park. Before the building of hydraulicworks, it received the Senegal waters during the flood (Tricart, 1957). It is actually regulated with 4main hydraulic pumping stations that control the flood in the park together with the river dyke (built in1964 and fixed in 1994) present between Rosso and Saint-Louis (Figure 6).

Although the water is mainly fresh, increases in salinity were observed in 1996 (11.5 g.l-1) and 1997(5.2 g.l-1) between March and July, which were attributed to the high evaporation (Sanogo, 1999).

This park is one of the first three Sahelian wetlands - the others being the Arguin bank and the internalNiger delta - that migratory Palearctic birds meet after their crossing of the Sahara desert (December).It hosts about 3 million of birds belonging to about 360 species, the most typical being the whitepelican (Pelecanus onocrotalus). In 1993, 193 000 anatidae and about 200 000 limicoles sand pipers(Himanatopus himanatopus, Recurvirostra avosetta, Limosa limosa, Calidris minuta, Philomachuspugnax) have been counted, 93% of them being Palearctic. This park also hosts a number of afro-tropical birds, either migratory or sedentary, like ducks (Dendrocygna bicolor, D. viduata,Sarkidiornis melanotos, Anas actua, A. querquedula, A. crecca, A. clypeata), gooses (Plectropterusgambensis, Alopochen aegyptiacus), flamingos (Phoenicopterus rosus, P. minor), pelicans (Pelecanusonocrotalus, P. rufescens), cormorants (Phalacrocorax carbo, P. africanus, Anhinga rufa), herons(Bublucs ibis, Ardea ralloides, A. cinera, A. purpurea, Nycticorax nycticorax), ibis (Mycteria ibis,Plegadis falcinellus, Threskiornis aethiopicus), and so on (BPDA-SCETAGRI et al., 1995). Somespecies like flamingos, pelicans, herons, ibis use also the park as a nesting area. Calculations madeindicate that pelicans only when they are at their maximum (10 000) could eat daily about 4 tons offish. Economic valuation estimates that the avifauna value would be 8.6 billion of CFAF (12.3 millionUS$ at the actual rate2).

The park is also one of the last area in the delta were wild vertebrates can be encountered some ofthem having been reintroduced (crocodile, dorcas gazelle). The most common are the wart hogs,jackals, red monkeys and the varanus of the Nile. Other species like Seba pythons, antelopes, gazelles,jennets, mongooses are also present. The manatees have not been seen since 1981 and seem to havedisappeared. Batrachians (toads, frogs) are also present in the Park.

2 1 US$ = 700 CFAF


Page 5 of 76

Figure 6. The Djoudj Bird National Park(from Sanogo, 1999)

The ichthyofauna was composed, in 1996, of 41 to 53 species belonging to 26 families, the Cichlidaebeing dominant (Pandare, 1996).

For all these reasons, the Djoudj Bird National Park belongs to the World Cultural Heritage (sinceOctober 1981). It is a Ramsar site (since 1977) and also belongs to the Bern Convention. It is the thirdornithological site in the world.

It has a common border with a similar park located in Mauritania, the Diawling National Park. Createdin 1991, it has an area of 160 km2 almost constituted of inundated lows. A Management Plan has beendiscussed and approved by all the stakeholders in 1997 and was supposed to be implemented between


Page 5 of 76

1997 and 2000 by French bilateral aid and IUCN (Hamerlynck and Cazottes, 1998). A lot of hydraulicinfrastructures are already in place.

In 1988, the population living in the 7 villages around the Park was 3055 inhabitants but with a highgrowth rate (about 4%) due to the development of riziculture in the Dbi low. The main activities ofthese populations are the irrigated agriculture (mainly rice on about 1940 ha), fishing and handicrafts.A study in these villages indicated that 84% of the households practiced rice growing, 73% breedingand 66% fishing (Ba et al. , 2001). Pandare and Sanogo (1996) estimated that the economic value offishing activities in the Park and its periphery was about 15 million CFA F, representing 48 tonnes offish landed annually.

The Djoudj National Park generated direct (from tourism) and indirect (from hunting in theneighbouring) revenues for a total of about 91 million CFA F in 1997. Between 1990 and 2000, thenumber of tourists that visited the site annually grew from 2,226 to 9,812 with a peak of 12,931 in1998. Moreover, it has positive impacts on the tourism industry in Saint-Louis, since it has beencalculated that in 1996 for example, 35.76% of the hotel revenues (about 2.2 million CFA F) werelinked to the visit of the Djoudj Park. On the other side, the annual budget of the Park has beendecreasing, being only 2.614 million CFA F actually (against 12 million in 1977/78) while the numberof guards also decreased from 27 in 1977 to 17 actually.

2.1.2 The Hann Bay

Limiting the south-eastern part of the Cap Vert peninsula, the Hann bay extends from the Bel Air capeto the village of Mbao along about 10 km of coast. From the administrative point of view, it is locatedpartly in the Dakar department, partly in the Pikine Dagoudane department. Due to its position relativeto Dakar, the bay is an appropriate place for industries that have a direct access to the sea and an easyand rapid access to the Dakar harbour. A lot of factories (SAR3, ICS4), of tank units (Shell and Mobiloil tankers) as well as two industrial frank zones are located all along the road bordering the bay,representing 60% of the Senegalese industries. Other economic activities like fisheries, urbanagriculture (in the "niayes") as well as leisure (yachting) can also be found close to or along the bay.The Hann bay is one of the two main landing sites for fishermen in the Dakar region (13,130 tonneslanded in 1995 representing 50% of the production of the region; JICA/MPTM, 1997). It is borderedby traditional "lebou" villages of fishermen like Hann Pcheurs, Thiaroye sur Mer, Mbatal and PetitMbao that were created during the years 1910 to 1920 and had a population of about 69,682inhabitants in 1988 (Sylla, 1994). Concurrently, this zone presents also residential areas.

Not only all these activities and populations generate a lot of wastes and sewage but also the Hann bayis a place where three main canals (canals IV, VI and VI bis) converge to let their polluted industrialand domestic waters entering the bay without any treatment about 100,000 m3 per year according tothe Direction of Environment (Figure 7). It is also located just southwest of the Dakar harbour.

This pollution of the sea is accompanied by a lot of other risks (i.e. fires, atmospheric pollution)mainly due to the presence of numerous dangerous industries or oil tanks. Some accidents alreadyoccurred in this bay: fire of the Shell tanks, ammoniac leak from the SONACOS in February 1992 thatdid more than 100 deaths, hydrocarbon leaks from the SAR canalizations.

The catastrophic state of this bay has generated a lot of studies, meetings and papers in thenewspapers. However, it is recognized that all this mobilization didn't solve the problem of this bay.

3 S.A.R.: African Society of Refinery4 I.C.S.: Chemical Industries of Senegal


Page 5 of 76

Figure 7. Exit of One of the Canals in the Hann Bay Beach(photo Niang-Diop, 2001)

2.1.3 Djiffere

Djiffere is a small village located on the Sangomar sand spit where mainly fishermen are present. The27th of February 1987, the Sangomar spit was breached about 2 km southwards where it is thenarrowest (120 m wide) (Figure 8). This place, named the Lagoba, experienced at least 2 breaches in1860 and 1928 (Diaw et al., 1990). Other temporary breaches have been recorded (1890, 1909, 1960and 1970; Saos et al., 1992). The reasons for this breaching (a strong west swell) are still not clear(Diaw et al., 1990).

Following the breaching, severe coastal erosion was noticed that not only destroyed the northernoceanic beaches but also deepened and widened the new mouth, now 4,000 m wide and 15 m deep.The sand spit retreated to the north at a rate of about 600 to 750 m per year (Ba et al., 1993); 1.29 mper day according to Thomas and Diaw (1997). The sediments mobilized by the erosion have beenpartly accumulated in the Saloum banks and channel (about 949 m3 per day; Thomas and Diaw, 1997)creating new sandy shoals (see the red arrow on Figure. 8c). Meanwhile the extremity of the SangomarIsland continued to extend southwards at a rhythm of about 178 m per year (Diaw, 1989; Diouf, 1992).

The coastal erosion has considerably affected the ecosystems, particularly the mangroves (Diaw,1989). But this will be discussed in the chapter 3 under the environmental impacts of coastal erosion.

2.2 Sensitive Areas

The three sensitive areas that have been identified are the three main estuaries, which are from Northto South: the Sngal delta, the Saloum estuary and the Casamance estuary. All are very flat areas.


Page 5 of 76

a. 9 May 1986 b. 25 April 1991 c. 21 October 1993

Figure 8. Evolution of the Sangomar Sand Spit between 1986 and 1993(from Thomas and Diaw, 1997)


Page 5 of 76

2.2.1 The Sngal Delta

Comprised between 16 and 1630'N, the Senegal delta has a triangular shape (Figure 9). It begins atRichard Toll and is limited by red dunes. Its area the Mauritanian side comprised - is about 492,000ha, with 29,600 ha permanently inundated (BDPA-SCETAGRI/ORSTOM/SECA/AFID/SERADE,1995). It is in fact a pseudo delta that is functioning since a long time as an estuary. However anumber of authors considered it as a delta invoking in particular the existence of other mouths(Maringouins, mouths of Boytet and Gavart rivers) but those have been closed a long time ago(Tricart, 1957). The Sngal River is connected with a number of tributaries and distributaries (Taou,Gorom, Djeuss, Lampsar, Trois Marigots in the Senegalese side) delineating a number of lows(Djoudj, Ndiael, Khant, Nguine) and lakes (Guiers). The river is deflected towards the South by a longsand spit, the "Langue de Barabarie" that is 22 to 27 km long (Sy, 1982).

The Senegal river was connected by the Taou, on its left side, with the Guiers lake (24,000 ha), 50km long and 7 km wide, located between 1555' and 1623' of latitude N and between 1604' and1623' of longitude W. This lake being the major source of fresh water for irrigation and for thedrinking water of the metropolitan area (20% of the needs in drinking water: 40,000 m3. d -1 quantitythat has doubled recently) has been partly artificialised (canals, pumping stations, dams) to control thequality of water.

Due to the drought and the need for more agriculture fields, it was decided to build two dams on theSenegal River, under the control of OMVS5:

the Diama dam, located about 50 km from the mouth, was opened in 1985. Its role was tostop the penetration of seawater in the river. It has a lake area varying between 11,000 and18,000 ha. The water lake behind allows for the irrigation of more than 70,000 ha, mainly forrice growing. It is opened when the flood comes (end of July) and maintains a level of 1.5 mIGN in its upstream part to ensure the irrigation;

the Manantali dam was opened in 1988. Located in Mali, 1,100 km from the mouth, itconstitutes a reserve of 12 billions of m3 of water. It was designed to control the riverdischarge that is actually 300 m3.s-1 against 780 m3.s-1 before. It will produce power for theOMVS members, the first production being for next year; and

these two dams were supposed to allow the development of 250,000 ha of irrigated lands.

Most of the wild fauna is present in the 3 main protected areas present in the delta:

the Djoudj Bird National Park (160 km2) which is a sanctuary for Palaearctic and afro-tropical migratory birds which stop here after the Sahara. It was created in 1971;

the "Langue de Barbarie" National Park (20 km2) hosts laridae as well as 3 species of marineturtles (Chelonia mydas, Caretta caretta, Dermochelys coriacea).It was created in 1976(decree 76 016 of the 9th of January 1976); and

the Guembeul Special Fauna Reserve (7.2 km2) is a winter site for numerous birds. It is alsoa site where the Gazella dama has been reintroduced and also where there is attempt to adaptthe Oryx damnati. The terrestrial turtle Sulcata geochelone is also present. It was created in1983 (decree 83 550 of the 30th of may 1983).

5 OMVS: Organization for the Management of the Senegal River


Page 5 of 76

Figure 9. The Sngal "Delta"(from Michel And Sall, 1984)

The Ndiael bird reserve has few birds actually due to the severe reduction of water inputs. Finally, asmall population of hippopotams is present close to Richard-Toll.

The population in the delta was estimated at about 330,000 inhabitants for the Senegalese part. Thispopulation is partly concentrated in towns (Saint-Louis, Richard Toll, Ross Bthio, Rosso, Dagana)located along the river: 56% of the population is urban in the delta (BDPA-SCETAGRI/ORSTOM/SECA/AFID/SERADE, 1995). Saint-Louis is an old colonial town funded in1659 and was the former capital of Sngal and Mauritania. With a mean altitude of less than 2.5 m itis subject to floods (Camara, 1968). The mean annual growth rate is 2.85% for the Dagana departmentwhile a rate of 12% was observed in Richard Toll due to the development of the sugar industry. Theconstruction of the dams and the availability of land attracted a lot of people in the region.

The main activities in the delta are: industrial sugar production around Richard Toll (about 7,520 ha in1980), rice growing in the lows present North of Ross Bthio (7,730 ha in big fields and 1,174 ha assmaller fields) (Michel and Sall, 1984), industrial tomato (production of 82,000 tonnes in 90/91),market gardening in the Gandiolais; fishing mainly in the Guiers lake and the Taou as well asbetween Saint-Louis and the mouth (Bousso, 1992). Tourism is based on the historic site of Saint-Louis and on the Djoudj Bird National Park.


Page 5 of 76

2.2.2 The Saloum Estuary

The Saloum estuary is located between 1335' and 1410' latitude north and 1603 and 1650'longitude west. It is a big estuarine complex with a drainage basin of 29,720 km2 (4,309 km2 for theestuarine part), opening in the Atlantic Ocean by three main distributaries with an estuarinefunctioning: the Saloum to the north, the Bandiala to the south and the Diomboss in between (Figure.10). The Saloum is relatively wide (1-2 km) and deep (13 to 25 m) between its mouth andFoundiougne but after till Kaolack it is narrow (


Page 5 of 76

The Saloum estuary is protected from the Atlantic Ocean by a long sand spit (between 14 and 19 kmlong; Diouf, 1992), the Sangomar spit, that stretches southwards and is fed by the north-south littoraldrift (Sall, 1982; Diaw, 1997). Between 1927 and 1987, this spit continuously extended southwards atvarious rates between 22 m.y-1 (1969-1972) and 120 m.y-1 (1946-1954) (Diaw et al., 1988, 1991)representing a global extent of 4 km. In 1987, a breach opened in the spit that is now divided in a spitand an island determining the presence of two mouths: the Lagoba mouth (>4,000 m wide) and theSangomar mouth to the south (1,800 m wide) (see Figure. 8). The Sangomar Island continued toextend southwards with a rate of 192.5 m per year (Diouf, 1992) while the part of the spit linked withthe continent eroded. Inside the estuary are small sand spits (Niodior spits) 2 to 3 km long, directednorthwards indicating the pre-eminence of flood currents in the estuary (Barusseau et al., 1985).

The fish population in the estuarine complex is represented by 114 species belonging to 51 families,which constitutes a relative high specific richness if compared with other estuaries (Diouf, 1996). Thedominant species is a resistant species, Sardinella maderensis. 39% of the species reproduce in theestuary, which is also a nursery (85% of the fishes are juveniles) (Diouf, 1996). Moreover, 60 to 65%of fishes are predators (Diouf, 1996).

There is one protected area, the Saloum delta national park which is 760 km2. It is a MAB BiosphereReserve and a Ramsar site. It is a place for breeding and feeding of the ichthyofauna, the manatee(Trichechus senegalensis), dolphins (Sousa teuszii) and 3 species of marine turtles (Lepidochelysolivacea, Chelonia mydas and Caretta caretta). A total of 70,000 birds were counted in 1996, mainlyflamingos, pelicans, herons, terns and Palearctic limicolous. There are also a mammal fauna likemonkeys (Colobus badius Temmincki).

The population of the Saloum estuary is mainly rural (80%) with few cities: Kaolack (157,551inhabitants) and Fatick (20,491 inhabitants). In 1992, the two departments of Fatick and Kaolack had apopulation of 536,115 inhabitants (7.2% of the total population and 14% of the coastal population).Administratively, the estuarine complex belongs to three regions: Fatick (departments of Fatick andFoundiougne), Kaolack (departments of Kaolack) and Thies (department of Mbour).

The main economic activities in the region are fishing, agriculture and tourism. There is also anintensive production of salt particularly at Kaolack (Compagnie des Salins du Saloum). Thecontribution of this region to the gross national product was 12.3% in 1992. Actually, the fishproduction is of about 10, 000 tons per year (Diouf, 1996). There is a lot of fisheries infrastructureswith five main landing points: Djiffere, Ndangane, Missirah, Sokone and Foundiougne. Thepopulation of fishermen is constituted of 5,400 residents and 2,300 migrants representing 22% of thefishermen present along the Senegalese coastline (Diouf, 1996). Complementary to this there is a highactivity of shell collection, mainly oysters (Crassostrea gasar) and bloody cockle (Anadara senilis).Agriculture production is dominated by the peanuts (53% of cultivated areas), followed by millet andsorghum (43%). The rice culture has regressed due to soil salinisation. Tourism is not as developed asalong the South Coast but there is a lot of small camps in the islands and along the Sangomar sand spitexploiting the mangrove and the sportive fishing.

2.2.3 The Casamance Estuary

The Casamance river, located south of Sngal, between 1230' and 13N, is about 350 km long with asmall drainage basin of 13,850 km2. The depths vary between 0.5 m upstream and 12 m close to themouth with a lot of shoals. The estuary itself (area of about 2,500 km2) is about 250 km long with a nilslope from Diana Malari at about 228 km from the mouth. About 5 km wide close to its mouth, theriver narrows upstream, reaching a width of about 2 km at 180 km from the mouth. It is partlyprotected from the open coast by a sand spit, the Presqu'le aux Oiseaux spit. It receives two maintributaries with almost no freshwater discharges: the Soungrougrou to the north with a drainage basinof about 4,700 km2 and the Diouloulou.


Page 5 of 76

The Casamance estuary is characterized by the presence of the mangrove which has been subdivided based on the sequence of mangal trees - in recent and old mangroves by Vieillefon (1977), the formerbeing mostly present in the western part of the estuary but also around Ziguinchor and traducing arecent extension of the Casamance river (Figure 11). Tannes are best developed and wider in themedium part of the estuary. This distribution of the geomorphological units is accompanied by amaturation of soils: hydromorphic soils in the west are progressively replaced by sulfato-acid soils tothe east which characterized the tannes (Vieillefon, 1977). In the medium and high estuaries,mangroves and tannes are bordered by low terraces about 1 m above sea level with sandy or clayeysoils. In 1977, most of these terraces were used as rice fields.

Figure 11. The Casamance Estuary (from Pages Et al., 1987)The Area Limited by the Dotted Line is the Limit of Extent of the Mangrove

One protected area, the Basse Casamance National Park (50 km2), comprises the last relicts of theGuinean forest as well as 50 species of mammals and 200 species of birds.


Page 5 of 76

CHAPTER 3

3. Impacts of the Main Environmental Issues in Senegal

The three main environmental issues as deduced from the scoring and scaling exercise are by priorityorder:

modification of stream flows (issue 1); modification / destruction of ecosystems (issue 12/13); and chemical pollution (Issue 6).

We will try, in the following section to identify what are the main environmental and socio-economicimpacts of these three main issues.

A special subchapter will be devoted to socio-economic impacts as deduced from the GIWA scoringmethodology.

3.1 Issue 1: Modification of Stream Flows

In Sngal, we observe two types of modifications of the stream flows: first a reduction of riverdischarges due to the drought, leading to an invasion of the river by seawater; second areduction/suppression of sea water excursions in parts of the river due to dams. The first type ofmodification is natural and observed, in particular, in the southern estuaries (Saloum and Casamance),while the second one is artificial and superimposed on the first one and characteristic of the Sngaldelta.

3.1.1 Reduction of Stream Flows: Constitution of Inverse Estuaries

3.1.1.1 Description

Between 1966 and 1970, a rupture in the climate has been observed giving rise to a prolonged droughtcharacterized by a reduction in the annual rainfall and in the length of the rainy season (from 5 to 4-3months in the Saloum basin) (DaCosta, 1993; Diouf, 1996; Malou et al., 1998) (Table 8). Dependingon the stations, the deficit is comprised between 5 and 43% (Malou et al., 1998). In the Saloum basin,this pluviometric deficit seems to begin in 1950 (Albaret and Diouf, 1994). Since then, a deficit of 10billion of m3 was calculated by Diouf (1996) (Table 9). A southwards displacement of the 500 mmisohyet of about 2 of latitude has been observed in the Sahelian regions between 1950 and 1970(Hubert and Carbonnel, 1986).

Table 8. Climatic Rupture of Some Littoral Stations (from Malou et al., 1998)

Mean annual rainfall (mm) DeficitStations

Year of therupture Before rupture After rupture mm %

Ziguinchor 1967 1576 1162 414 26Oussouye 1967 1561 1223 339 22

Foundiougne 1966 853 564 289 34Mbour 1969 773 489 283 37

Dakar-Yoff 1969 595 341 254 43Podor 1970 317 200 117 37


Page 5 of 76

Table 9. Evolution of Annual Rainfall in the Saloum Basin (from Diouf, 1996)

Stations 1931-1965 1961-1985 DeficitFoundiougne 893 mm 636 mm 29%

Kaolack 796 mm 612 mm 23%Fatick 810 mm 582 mm 28%

One consequence was a reduction in river discharges and an invasion of seawater in all the estuaries(Table 10).

Tableau 10. Fluvial Discharge Evolution in Some Estuaries1 Pages et al., 1987; 2 Diop (1986); 3 Olivry and Chastanet (1986); 4Kane (1985)

Period Mean discharge Peak discharge1903-1984 715 m3.s-1 9,340 m3.s-1 (1906)

Sngal3, 41970-1984 421 m3.s-1 995 m3.s-1 (1984)

1976 0.29 m3.s-1Nma-Ba2 (in theSaloum estuary) 1981 0.03 m3.s-1

Before 1968 6.4 m3.s-1 32 m3.s-1Casamance1

1968-1983 1.7 m3.s-1 6.8 m3.s-1

The annual module of the Senegal River was reduced from 780 m3. s-1 between 1903 and 1969 to 264m3. s -1 in 1972 (Michel and Sall, 1984) indicating a trend to the reduction of the stream flow - sinceabout 1965 - superimposed on a cyclic evolution (Olivry, 1983; Blanc and Faure, 1989). The historyand mechanism of seawater intrusion in the Sngal River has been reconstructed by Gac et al. (1986).Just before the opening of the Diama dam, seawater invaded the estuary till about 250 km upstream,reaching Podor. According to Tricart (1957), the Guiers Lake began to be brackish in 1870 and in1954, the seawater entered in the delta till Richard-Toll (Tricart, 1955). In the Casamance estuary,seawater invaded the river till Diana Malari, 218 km upstream and the downstream reach of theSaloum is completely saline.

Parallelly, due to the high rates of evaporation and the relative low depths in the upstream parts of therivers, the seawater concentrated by evaporation in the upper reach of the rivers leading to hyperhalinewaters (Jusserand et al., 1989). Savenije and Pages (1992) showed that this hypersalinity of theestuaries was not only dependent on a reduction of freshwater discharges but also on the succession ofdry years.

We thus observe "inverse" estuaries like those of Saloum and Casamance. The hydrodynamic regimeof these inverse estuaries, as measured in the Saloum estuary (Figure 12), presents 4 main differencescompared to normal estuaries (Barusseau et al., 1985, 1986):

the flood lasts longer than the ebb (respectively 7h and 5h25 for the Saloum river); current velocities are higher during flood than during ebb, enhancing the seawater inflow; the duration of high water period is longer than that of low water; and more seawater enters in the distributaries than it flows back. This will be partly due to the

attenuation effect exerted by mangroves and bolons. In 1982, for example, it was calculatedthat between 66 and 80% of the seawater entered in the estuary flowed back (UNESCO,1985; Barusseau et al., 1986).


Page 5 of 76

Figure 12. Tidal Current Velocities and Tidal Range Evolution in the Saloum River in Front ofDjiffere (20 April 1982) (from Barusseau et al., 1985)

One main consequence of this regime is that estuarine salinity is always higher than seawater salinity.The water salinity increases upstream. Modelling of this salinisation was attempted (Pages andDebenay, 1987; Savenije and Pages, 1992).

In the Saloum estuary, salinities up to 55%o were recorded at about 55 km from the mouth(Foundiougne) (Barusseau et al., 1985) and they increase upstream (88%o recorded in Kaolack in1978; UNESCO, 1985). Records between 1928 and 1993 indicate a clear trend towards an increasingof maxima and minima of salinity in the Saloum estuary (Figure 13). According to Diouf (1996), theSaloum River began to be a reverse estuary in 1961.

It was also observed that the dominance of seawater hydrodynamics induced the migration of theorganic matter from the mangrove areas to the upstream reaches of the river (Diouf, 1996). Moreoverthe time organic matter spends in the estuary is more important than in normal estuaries where organicmatter is rapidly exported to the shelf. This explains the relative specific trophic richness of theestuary (Diouf, 1996).

In the Casamance estuary, this situation began to occur around 1970 (Savenije and Pages, 1992). Infact, the water budget of the Casamance estuary became negative since 1975 when the annual rainfallbegan to fall below 1,050 mm. Debenay et al. (1994) indicate that this transformation in anhyperhaline inverse estuary took no more than 10 years. A salinity peak whose position andimportance vary from year to year was discovered (Pages et al., 1987) and salinities up to 172%o weremeasured in June 1986 at about 220 km from the mouth which can be considered as a record whencompared with other estuaries (Pages and Debenay, 1987). This salinity peak seems to separate two


Page 5 of 76

domains: one upstream (representing about 15% of the total river area) where hyperhaline waters arequite isolated from the sea, becoming concentrated brines (Debenay et al., 1994) and one downstreamwhere a slow renewal of the waters could be possible. The upstream part of the river is also the richestin organic matter (up to 80 mg of dissolved organic carbon per litre in 1990) and chlorophyll, the mainsource of organic matter being linked with Phragmites swamps (Debenay et al., 1990a).

Figure 13. Evolution of the Minima and Maxima of Salinity in the Saloum River Between 1928and 1993 (from Diouf, 1996)

3.1.1.2 Environmental Impacts

The main environmental impacts of this reduction of stream flows are:

the salinisation of soils leading to sulfato acid soils; the salinisation of aquifers; the modifications of flora and fauna; and other consequences like the diminution of fine sediments to the estuaries have impacts on the

capacity of the mangrove to extend.

Salinisation and Acidification of Soils

In almost all the estuaries, but particularly in the Saloum and Casamance estuaries, the persistentdrought has induced processes of salinisation and acidification of soils leading to acido-sulfatic soilsthat characterize the "tannes" (Boivin et al., 1986; Sow et al., 1994). In 1991, it was estimated that soilsalinisation affected 30,000 ha in the Sngal delta, 90,000 ha in the Saloum estuarine domain,140,000 ha in the fluvio-continental part and 400,000 ha in the Casamance basin (Sadio, 1991).

Salinisation of the soils - salt content of about 5 times that of the sea water for Marius et al. (1986) - isdue to the difficulty of evacuation of the salts in relation with the absence of slope in the downstreamparts of the rivers. This induced the formation of salted crusts (Marius et al., 1986). Another propertyof the mangrove soils, particularly those under Rhizophora, is the formation of iron sulphurs likepyrite by sulphate reduction realized by bacteria of the type Desulfovibrio. The acidification process ofthe soils is progressive (Loyer, 1985). A first step is the oxidation of the sulphur compounds by


Page 5 of 76

sulpho-oxydizing bacteria (type Thiobacillus) in sulphates inducing a rapid decrease of the pH (till 2);this is possible when the reducing environment is transformed in an oxidized environment (forexample by lowering of the water table). In the presence of potassium or sodium salts, this leads to theformation of a characteristic iron sulphate, the jarosite [KFe3 (SO4)2 (OH)6] (Kalck, 1978; Loyer,1985; Boivin et al., 1986). When these soils are dewatered the acid sulphates can be hydrolysed andtransformed in iron hydroxides (Loyer, 1985). In the Casamance estuary, Marius et al. (1986) alsoobserved the neoformation of smectites due to the dissolution of diatoms and also the mineralizationof gypsum that was unknown in Casamance till 1972. In the Saloum estuary, Sadio (1991) observedvery high rates of salinity as well as formation of gypsum due to the hyper oxidation of the pyrite. Thispedogenesis induces a sterilization of soils that are mobilized by the winds increasing the Aeolianerosion.

In Casamance, upstream banks of the river are particularly salted due to the accumulation of salts inbottom sediments and groundwater, then on the banks. The main consequences have been anabandonment of rice fields but also extraction of salt in the region (Debenay et al., 1994). Boivin et al.(1986) estimated that the salted front was located close to the border of the continental plateau.

This situation had consequences on the riziculture in the Casamance estuary requiring modifications inthe agricultural practices but also in the conception of anti salt microdams (Boivin et al., 1986).

Salinisation of Aquifers

In the Saloum estuary, salinities up to 130%o were measured in the aquifers present under the "tannes"(Diop, 1986). These salinities can be explained by the vertical and lateral exchanges with the Saloumriver. In Casamance, the drought induced a lowering of the piezometric level for the continentalplateau aquifers as well as a flow of fluvio-marine aquifers towards the plateau, contaminating itsaquifer (Boivin et al., 1986). According to Marius et al. (1986), aquifers were 3 times more salted thanseawater.

Modifications of Flora and Fauna

Saloum

The mangrove ecosystem has been reduced in the medium and upstream parts of the Saloum river dueto the salinisation and acidication of soils, being replaced by "tannes" (Figure 14). This degradation ofthe mangrove begins at about 40 km from the mouth where confined hyperhaline waters are present(Diouf, 1996). Other species like Cocos nucifera and Elaeis guineensis disappeared from some placesor are highly degraded.

On the fauna, the main consequence of the environmental degradation has been the quasi-disparitionof continental species (with the exception of Hemichromis fasciatus). In the hyperhaline reaches of theSaloum (about 50 km from the mouth) the phytoplankton is represented only by diatoms (Diouf,1996).

The microfauna of ostracoda and foraminifera is characterized by a reduction in species and number ofindividuals upstream (Ausseil-Badie and Monteillet, 1983). In 1985, Carbonnel indicated that highsalinity was responsible for the death of certain ostracoda while others were obliged to migrate.

A diminution of oysters has been observed but this evolution could be due not only to hyperhalinity ofthe estuary but also to destructive human activities (cutting of the mangrove roots where are theoysters).

In the Saloum estuary, all fishes belong to marine and estuarine species (85 species; Diouf, 1996),especially to the Mugilidae (Diouf and Deme-Gningue, 1992). According to Diouf (1996), thehyperhalinity observed in the upstream reaches of the river induced: the development of salt resistant


Page 5 of 76

species like Sarotherodon melanotheron (Ci6), Elops lacerta (E), Tilapia guineensis (Ci), Lizafalcipinnis (M), L. dumerili (M), Gerres nigri (G), Sardinella maderensis (Cl), Ilisha africana (P) andEtmalosa fimbriata (Cl); a simplification of trophic chains; a low number of species in reproduction.There is no pure continental species. Predators dominate the structure of the population. The parts ofthe rivers that have an abondant ichtyofauna are characterized by a salinity generally lower than 55%oand an important trophic enrichment linked to the presence of mangrove.

Casamance

After 1970, the mangrove retreated although the figures are different depending on the authors. Sall(1983) observed that between 1973 and 1979 the tannes area increased (+107 km2) while themangrove area was reduced (-87 km2). Marius (1985) estimated that 70 to 80% of the Rhizophoradisappeared since 1979 with a great extension of "tannes" while Badiane (1987) indicated a reductionof the mangrove area - that occupied between about 1,200 km2 before 1968-1970 - to 930 km2 in 1973and 830 km2 in 1983. The Rhizophora were partly replaced by Avicennia but this species was finallyreduced by hypersalinity.

However, Paradis (1986) indicated that in some places, death of the mangroves was due to humanactivities like for example building of dams (case of the Guidel dam), riziculture that could beresponsible of the destruction of at least 25% of the mangroves, as well as salt exploitation that usesmangrove as fuel wood.

During the same period a retreat 100 km upstream of reed swamps made of Phragmites communis wasalso observed. In 1990, only sparse green reed beds subsisted due to groundwater seepage. Also, otherspecies like palm trees (Aeleis, Borassus Aethiopicum) disappeared due to the salinisation of the soilsand this was observed up to 50 m from the estuary banks (Savenije and Pages, 1992).

Surveys made between 1984 and 1990 allowed to follow the impacts of the hypersalinisation of thewaters on the microfauna (Foraminifera and Ostracods mainly) and on the macrofauna (birds inparticular) (Debenay, 1984; Debenay et al., 1990b; 1994).

Foraminifera and Ostracoda seem to follow the same evolution with first an extension of marinespecies upstream (between 1982 and 1985), then a colonization of almost all the river by veryeuryhaline species (Cyprideis mandviensis for Ostracoda and Ammotium salsum for the benthicForaminifera (Figure. 15 C and D).

Also, the average weight and number of catches of the shrimp Penaeus notialis have collapsed since1980 (Le Reste and Collart-Odinetz, 1987).

The ichtyofauna is characterized by a loss of taxonomical biodiversity with increasing salinity. Thedownstream part of the river (between the mouth and Ziguinchor) presents the more diverse and richfish population with more than 70 species, the main families being the Carangidaea (7 species), theMugilidaea (8), the Scianidaea (5), the Cichlidaea and Pomadasydaea (4). After Goudomp, the fishpopulation is reduced by half and in sursaline waters only 5 to 6 species are present. Then, when thesalinity is higher than 70%o, we have monospecific populations of Sarotherodon melanotheron(Albaret, 1987; Diouf et al., 1993; Pandare et al., 1997). Moreover, the size of the fishes decreasesupstream. The salinity peak of 172%o in may 1986 has been responsible for the disappearance offishes during more than three months (Pandare et al., 1997).

6 Ci: Cichlidae; Cl: Clupeidae; E: Elopidae; G: Gerreidae; M: Mugilidae; P: Pristigasteridae


Page 5 of 76

A

B

Figure 14. Evolution of the Mangrove Ecosystem in the Saloum EstuaryA: Mangrove Close to the Mouth; B: Relict Mangrove Progressively Replaced by "Tannes"

UpstreamPhotos: Niang-Diop I. (1991)


Page 5 of 76

Figure 15. Evolution of Some Characteristics of the Casamance Estuary Between its Mouth andabout 250km Upstream (Debenay et al., 1994) A: Tide Amplitude and Delay; B: Salinity; C:

Foraminifera; D: Ostracoda; E: Chlorophyll (for Stations Position see Figure 11)

The distribution and abundance of water birds (about 55 species) strictly follows the water zonationwith a great abundance of pelicans (Pelecanus onocrotalus) and herons (Ardea purpurea and Ardeolaralloides) in the parts of the river with a pullulation of Sarotherodon melanotheron (Guillou et al.,1987). The passage to extreme saline waters is marked by the apparition of Sterna nilotica and Sternaleucoptera (Debenay et al., 1990a).


Page 5 of 76

In 1990, limited places with trapped freshwater were observed downstream of Kolda. They offer arefuge for the manatee (Trichechus senegalensis), which doesn't support saline waters but also forfreshwater fishes of big size (Debenay et al., 1990a).

Debenay et al. (1994), based on the observation of the effects of a better rainy season, consider that areversion to the normal conditions will take longer than 15 years, if it is possible at all.

3.1.1.3 Socio-Economic Impacts

The main socio-economic impacts linked with the increased salinity of the Saloum and Casamancerivers are the followings:

there is a general problem of potable water availability in the region; the availability of fertile soils has been reduced due to salinisation and acidification.

Riziculture has been abandoned in the Saloum estuary since at least 20 years and is reducedin the Casamance estuary. In Casamance, rice growing moved to the plateau. This is mainlydue to the acidity of the soils, rice being not able to cope with pH lower than 4;

more generally, peasants have been obliged to diversify their production. The diola ethnicgroup that is based on the riziculture now produces palm oil and wine, coconuts, fruits andcan also develop the fishing and oyster collect (Diop, 1986). This is partly due to the fact thatsulfato-acid soils considerably limit the possibilities of agriculture production;

according to Diouf et al. (1993), the modification in stream flow could be responsible for thedecrease in the estuarine fisheries annual production between 1972 (about 5

Documents

1 Senegal Report country wise