1 Senegal Report on Potential of Energy

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 Côte 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 Sénégal 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 Sénégal 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 D’identification: 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 Sénégal "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 Sénégal 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

Sénégal 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

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Executive 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.

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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 doesn’t 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 doesn’t 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 doesn’t 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.

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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

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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

Senegal National Report 040302.

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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 Côte",rectilinear, where beaches are part of a wide dune system while south of the peninsula is the"Petite Côte" 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 Côte" zone, from Saint-Louis to Dakar; the "Petite Côte" 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).


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


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

Mean AnnualRainfall

Mean AnnualTemperatures

Mean AnnualHumidity

"Grande Côte" zoneSaint-Louis (16°03'N, 16°27'W)Dakar (14°44'N, 17°30'W)

265.2 mm413.5 mm

27.5°C25°C

64.8%75.9%

"Petite Côte" and Saloum zoneKaolack (14°08'N, 16°04'W) 607.2 mm 28.6°C 55.4%Low Casamance zoneZiguinchor (12°33'N, 16°16'W) 1,251.9 mm 27.2°C 67.4%

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

1.1.3 Coastal Hydrodynamics


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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.


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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 14°40’N), 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.


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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 Côte", 130,000 tonnes for the "Petite Côte" and40,000 to 60,000 tonnes for Casamance (Barry-Gérard 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-Gérard 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


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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 République du Sénégal, 1993)

Regions PopulationPercent of the Total

PopulationDensity

Saint-Louis 826,343 9 19Louga 550,585 6 19Thiès 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


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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 Sénégal (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.


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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).


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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 16°30'N and 16°10'W, at about 60 km northwest of Saint-Louis, the Djoudj BirdNational Park belongs to the Sénégal 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


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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


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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 Débi 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 Pêcheurs, 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


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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 Sénégal delta, the Saloum estuary and the Casamance estuary. All are very flat areas.


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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)


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2.2.1 The Sénégal Delta

Comprised between 16° and 16°30'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 Sénégal River is connected with a number of tributaries and distributaries (Taoué,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 Taoué, on its left side, with the Guiers lake (24,000 ha), 50km long and 7 km wide, located between 15°55' and 16°23' of latitude N and between 16°04' and16°23' 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


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Figure 9. The Sénégal "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 Béthio, 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 Sénégal 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 Béthio (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 Taoué 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.


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2.2.2 The Saloum Estuary

The Saloum estuary is located between 13°35' and 14°10' latitude north and 16°03’ and 16°50'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 (<500m) with depths always less than 8 m. TheDiomboss has a main width of 4 km with depths between 10 and 25 m. The Bandiala is relativelynarrow (less than 500 m) and shallow (depths generally less than 10 m). They separate two maingroups of islands covering about 80,000 ha: the Gandoul islands to the north and the Betanti andFathala islands to the south. The three distributaries are interconnected by a dense network of smalltidal channels, the so-called "bolons". Mangroves are present all along the channels (590 to 800 km2;Blasco, 1983; Diop and Ba, 1993) but are more and more reduced northwards where they areprogressively replaced by barren areas, the so-called "tannes" (Barusseau et al., 1986). Diaw et al.(1993) described the "tannes" as barren areas, flooded during high spring tides and characterized bysalted soils. The highest parts of the estuary are represented by sandy barriers (2-4 m high) and"kjokkenmoddinger" that are anthropic middens (3m high) attesting a long history of the humanoccupation in this region (Mbow, 1993).

Figure 10. The Saloum Estuary(from Diouf, 1994)


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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 Sénégal, between 12°30' and 13°N, 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'île 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.


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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.


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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 Sénégal, 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 Sénégaldelta.

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


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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)

Sénégal3, 4

1970-1984 421 m3.s-1 995 m3.s-1 (1984)1976 0.29 m3.s-1Néma-Ba2 (in the

Saloum estuary) 1981 0.03 m3.s-1

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

Casamance1

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 Sénégal 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 theattenuation 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).


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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


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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 thecapacity 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 Sénégal 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


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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


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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


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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)


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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).


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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 50,000 tons) and1990 (30,000 tons). Moreover the abandonment of the Katakalouss project of shrimp culturehas been partly attributed to the high salinities (Bousso et al., 1993); and

• the salt extraction has raised.

3.1.2 Reduction of Sea Water Intrusion/Permanence of Freshwaters Due to DamConstruction

In the Senegal delta, modifications of stream flow are characterized, since the functioning of theDiama dam and then of the Manantali dam, by the permanence of freshwaters – upstream of Diama -in places that where regularly affected by sea water as well as a flood control. Downstream of theDiama dam, freshwater are only present after the opening of the gates to evacuate the flood (Ba,1993). The main characteristic of this part of the delta is the sudden change between an homogeneoussalted estuary functioning like a lagoon and a water plan invaded by turbid freshwaters during theflood (Ba, 1993). Depending on the places, the environmental impacts differ.


They will be examined for the two main environments encountered now in the Sénégal delta.

The downstream part of the river (between Diama and the mouth) is subject to different changes:

• very rapid variations in the salinity (between 0 and 40%o) - during the opening of the damgates - disturb the aquatic fauna (BDPA-SCETAGRI/ORSTOM/SECA/AFID/SERADE,1995);

• the permanence of brackish waters has induced the salinisation of the soils present in theGandiolais, the Trois Marigots zone as well as the Ndiael low with consequences on thevegetation, particularly in some reserves (Gueumbeul, Ndiael). It was also considered thatthere was a risk that actual mangroves disappear being replaced by tannes with sulfato-acidsoils (BDPA-SCETAGRI/ORSTOM/SECA/AFID/SERADE, 1995). A recent comparativestudy of the geomorphologic units present on the Babagueye islands (located just South ofSaint-Louis) showed a retreat of the mangroves between 1978 and 1989 and their


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replacement by tannes (Soumare, 1996). The same author observed an extension ofAvicennia that is more salt tolerant than Rhizophora and attributes all these modifications tothe quasi absence of freshwater influx;

• the reduction in the river discharge has determined a predominance of the sea dynamicsleading to a general southwards growth of the Langue de Barabarie sand spit, the building ofa mouth bar while the Mboumbaye lagoon retreated by about 2,500-3,000 m between 1986and 1990 (Ba et al., 1995; Soumare, 1996);

• there is a tendency towards the infilling of the estuary by fine sediments, specially betweenGandiole and the dam (Ba et al., 1995);

• Tympanotonus fuscatus seem to have disappeared from the mangroves (Ba et al., 1995); and

• according to Albaret and Diouf (1994), the specific composition of fish populations didn'tchange but the reduction of the estuarine environment (from 200 to 50 km) determined areduction of the habitats available thus inducing a deficit in the recruitment of estuarinefishes but also of some marine fishes. From Diama to the mouth, only are present marinespecies like tilapias, mugilidae and ethmaloses representing respectively 40%, 30% and 20%of the total captures (Bousso, 1992). Seck (1988) observed a reduction in the landings ofshrimps, mullets and tilapias two years after the beginning of the Diama dam as well as areduction in the size of shrimps and tilapias. The presence of the dam, as a physical obstacle,determines the death of fishes that want to migrate upstream; great quantities of Clarias havebeen observed in this situation by Pandare et al. (1992). Some species like Polydactylusquadrifilus, Pseudotolithus elongatus, Pomadasys jubelini, Pomatomus saltatrix are notmore present in this part of the river (Bousso, 1992);

The upstream part of the delta (between Diama and Dagana) is characterized at the contrary by thepermanence of freshwaters which induced the disparition of estuarine and marine species (Albaret andDiouf, 1994). However, a new wetland area was created and since then has been used mainly by birds.The main negative impacts were:

• important modifications in the vegetation were observed, specially in the Guiers lake, thatwere induced by inundation of larger areas by freshwaters (Cogels et al., 1993). Typhaaustralis began to expand in 1986 due to the stabilization of the lake level and desalinization(salinity reduction of 20% between 1989 and 1992, BDPA-SCETAGRI/ORSTOM/SECA/AFID/SERADE, 1995) after a long period of regression dueto the drought (Thiam, 1983). The area occupied by Typha was of about 1,000 ha in 1992while it was only 170 ha in 1980 before its disparition in 1982-83; in 1999, it occupied morethan 6,500 ha (Matera and Malaisse, 1999). More spectacular is the invasion since 1990 -specially in the southern part of the Guiers lake but also in the Djoudj Park - by Pistiastratiotes (the Nile salad), a floating macrophyte. A report indicated the danger of thismacrophyte for the environment (Matera and Malaisse, 1999). Two other plants,Potamogeton schweinfurthii and Ceratophyllum demersum are also expanding in the Guierslake. In 1999, began the invasion by Salvinia molesta another floating macrophyte. The mainconsequences of this proliferation of Typha and Salvinia are: the reduction of watercirculation and the development of granivorous birds;

• proliferation of Bulinus guernei, which is a vector of Schistosoma haematobium that givesthe urinary bilharziosis and of Biomphalaria pfeifferi , vector of Schistosoma mansoni that isresponsible for the intestinal bilharziosis. These two molluscs were already present in thelake in 1981 (Vincke and Cisse, 1983). In 1990, the last species represented 69% of themolluscs present in Richard Toll (Niang, 1999);

• diminution of gazelles in the Djoudj Park due to the inundation of their ecological areas(Tiguet zone) (Ba et al., 2001); and

• due to the permanence of freshwaters as well as to the damming of the river, there is no moreestuarine species in this part of the delta. In the Guiers lake as well as in the Sénégal river,the development of Tilapia (representing about 50% of the captures in the Guiers lake) was


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observed (Bousso, 1992). In the Djoudj park, fishes encountered are mainly freshwaterspecies belonging to the Cichlidae family (Oreochromis niloticus, Sarotherodonmelanotheron, Tilapia guineensis, Lates niloticus) while pure estuarine species havedisappeared the only estuarine species still present being euryhaline ones (Elops lacerta, Lizafalcipinnis, Mugil cephalus, Monodactylus sebae) (Sanogo, 1999). Also, the mean weight offishes has lowered, with the exception of the tilapias (Bousso, 1992).

The regulation of the river discharge has had other consequences on the Guiers lake (Cogels et al.,1993). The lake level is higher (plus 0.54 m as an average) than before the Diama dam that loweredthe mineralization of the lake (Figure. 16). However, the rate of evaporation has increased (from 85%to 90%).

Figure 16. Evolution of the Guiers Lake Level Before and After the Diama Dam(from Cogels et al., 1993)


The main negative consequences are the followings:

• The outbreak of intestinal bilharziosis (Schistosomiasis; Schistosoma mansoni) in regions ofthe delta previously free of this disease but also located outside of the normal area of thisdisease (Handschumacher et al., 1992). The town of Richard Toll (about 50 000 inhabitantsin 1990) was the first point where this disease has been identified in the delta. Between 1988and 1992, the prevalence increased from 0.8 to 70.4% (Talla, 1993). This is linked with thedevelopment of Biomphalaria pferffeiri, intermediary host of Schistosoma mansoni that livesin freshwaters. The authors indicate that migration of populations, the lack of accessibledrinkable water as well as the weakness of sanitary infrastructures are aggravating factors. Infact, few cases of intestinal bilharziosis have been observed in Ross Bethio and Khor.Moreover, Gaye et al. (1993) indicated that other intestinal parasitoses due to differentprotozoa (Entamaeba coli, Giardia sp., Ascaris sp., …) as well as malaria could alsoincrease due to the quasi permanent presence of freshwaters;

• The macrophyte invasion of the lakes are correlative of the expansion of the malaria sinceTypha as well as Pistia host the anophelus larva (Cogels et al., 1993);

• it has been also observed the reaparition of livestock diseases linked to the permanence ofinundated areas, like: the Rift valley fever, intestinal bilharsiosis (Schistosoma bovis), as wellas hematoparasitoses (Amaplasmae marginalae, Theileria annulata) (BDPA-SCETAGRI/ORSTOM/SECA/AFID/SERADE, 1995);


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• the evolution of the mouth induces more problems of navigation and more specifically ofaccess to the river from the sea;

• the wide availability of water created new conflicts for the use of the land, specially betweenfarmers and stockbreeders but also between regional (OMVS) and national or private (CSS)organizations (Niang, 1999); and

• fishing activities are reduced due to the invasion of floating macrophytes and even thepresence of Typha on the river and lake banks creates difficulties of access for the men andthe livestock. On another side, Diouf and Bousso (1988) predicted an increase of fishproduction of about 500 tonnes in the Guiers Lake due to its extension.

However, the change in hydrological regime of the Senegal, allowed for more water availability,especially for irrigated agriculture but also as drinking water.

3.2 Issue 12-13: Modification/Destruction of Ecosystems

The modification and/or destruction of habitats are more or less a consequence of the two mainenvironmental issues identified above although other problems like drought can be responsible forthese changes.

In Sénégal, the modification of ecosystems is mainly due to the drought as well as problems likepollution. Some good examples have been described as part of the consequences of the two firstenvironmental issues. At a global scale, these modifications are relative to the following ecosystems:the mangrove, the "niayes" and wetlands. Moreover, coastal erosion is a recurrent problem of theSenegalese coastlines, the case of Djiffere being particularly spectacular. We will examine impacts ontwo ecosystems: mangroves and beaches.

3.2.1 Mangrove Ecosystem

The main recorded evolution of this mangrove is its area reduction due to sulfato-acid soils which areresponsible for the replacement of mangroves by "tannes". In the Saloum estuary, this is observedmainly in the central and eastern parts of the estuary where the number of dead mangrove increases tilla complete disappearance of the mangrove after Foundiougne. Together with this reduction in the area,there is a reduction in the size of the trees (Diouf, 1996). As indicated before, the mangrove inCasamance has retreated after 1970 although the figures are different depending on the authors. Sall(1983) observed - between 1973 and 1979 - an increase in the area of tannes (+107 km2) while themangrove area was reduced (-87 km2) while Marius (1985) estimated that 70 to 80% of theRhizophora disappeared since 1979. Badiane (1987) indicated a reduction of the mangrove area - thatoccupied between about 1200 km2 before 1968-1970 - to 930 km2 in 1973 and 830 km2 in 1983. TheRhizophora were partly replaced by Avicennia but this species was finally reduced by hypersalinity.According to Rue (1994), the observed retreat of the mangroves in Sénégal could be related to theweakness of the fluviatile behaviour of the rivers (linked to the diminution of freshwater flow itselfinduced by the prolonged drought) that induces the growth of the sand spits limiting the estuaries thusdiminishing the entrance of sea water in the estuary. This, in turn, will favour the salt penetration inthe soils thus allowing the development of tannes. It will also limit the possible extension of themangroves as well as the area susceptible to be inundated. This, combined with a lack of pelitic inflowwill contribute to the reduction of the area covered by mangroves.

Another evolution of the mangrove in the estuarine system was observed due to the breaching of theSangomar sand spit in 1987. The important quantities of sands coming from the coastal erosion of theoceanside of the spit accumulated partly in the external fringe of the mangroves just in front of thenew mouth. According to Guisse (oral communication), this substrate change is responsible for thedeath of the mangroves.


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3.2.2 Sandy Beaches

There are numerous places along the Senegalese coastline that experience coastal erosion. The rates ofcoastal retreat are comprised between 1 and 2 m per year (Niang-Diop, 1993).

The case of Djiffere illustrates perfectly the situation when coastal erosion takes place on a sand spit.The rates of coastal retreat are very high (more than 20 m per year according to Ba et al., 1993) andthe main environmental impacts can be summarized as follows.


The opening of a new mouth of the Saloum River due to the breaching of the Sangomar sand spit hashad the main following environmental impacts:

• the mangrove ecosystem in front of the new mouth has been considerably disturbed. Theimportant quantities of sands coming from the coastal erosion of the oceanside of the spitaccumulated partly in the external fringe of the mangroves just in front of the new mouth.According to Guisse (oral communication), this substrate change is responsible for the deathof the mangroves. However, the mangrove is regenerating behind along the bolon wherewaters are quieter;

• there has been considerable accumulations of sands not only along the riverbanks, speciallyclose to Djiffere, but also in the channels, particularly those used for the transport betweenDjiffere and the villages of Niodior and Dionewar;

• the beaches located along the northern part of the Sangomar sand spit are retreating asevidenced by the presence of roots along the beaches; and

• In front of the new Saloum mouth (located at Lagoba), the important hydrodynamisminduced a reduction in species and biomass. The few species present (Gerres nigri,Eucinostomus melanopterus, Tilapia guineensis, Epinephelus aenus and Mugil cephalus)also characterize the upstream reaches of the river (Diouf, 1996).


The main socio-economic impacts of the breaching have been (Diaw, 1989):

• destruction of one fishing factory and also of the house of the guards belonging to theSaloum Delta National Park leading to the closing of this unit in august 1989;

• abandonment of the village of Palmarin that has been rebuilt on the other side of the road;

• difficulties of displacement of populations to the villages of Niodior and Dionewar, speciallyduring low tide (Ba et al., 1993);

• displacement of a tourist camp inside the islands; and

• new tourism opportunities in Djiffere due to the creation of beaches along the riverside.

3.3 Issue 6: Chemical Pollution

In Sénégal, chemical pollution is well evidenced in the Hann bay but other places present indices ofchemical pollution although the lack of measurements doesn't allow a clear characterization of thispollution.


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3.3.1 Description

The Hann bay is located in the Dakar metropolitan area where 35,000 m3 of used waters weregenerated daily in 1992, 15,000 m3 being industrial sewages The main types of products responsiblefor the degradation of the Hann bay are the followings (Table 11):

• the discharge of different types of products but also hot waters by diverse industries presentall along the bay: chemical colorants, products with basic pH, acid products,phosphogypsum, hydrocarbons, solvents, organic matters and compounds;

• solid wastes by fisheries and abattoirs; and

• non treated industrial and domestic sewages brought on the beach by canalizations.

Table 11. Types of Polluted Products Entering the Hann Bay

Industries and/or Activities Responsible Types of ProductsTextile industry: ICOTAF, SOTIBA Chemical colorants, hot waters, basic products

Fertilizer and pesticides industry: ICS, Senchim Acid products, hot waters, phosphogypsumPetroleum industry: SAR, oil tankers and garages Hydrocarbons, oilsPlastic industry: SAPEM, SENEPLAST, SIMPA,

ENSEMESolvents

Pharmaceutical industry: SIPOA/ParkDavis Polluted watersFisheries (SENEPESCA, InterCo, Sardinafric,

Blum Africa,…) and abattoirs (SERAS)Solid wastes, bloody waters

Paper industry: ROCHETTE, SIPS Waters enriched in organic matterFood industries: NESTLE, SEVEN UP Hot waters enriched in organic matter

It has been estimated by the Direction of Environment that about 100,000 m3.year-1 of untreatedsewage are rejected in the bay by diverse canalizations or directly on the beach. Domestic wastes,produced by the local populations, have been estimated as follows: 5,000 to 14,000 kg.day-

1.inhabitant-1 for solid wastes and 200,000 to 401,000 l. day-1.inhabitant-1 for liquid wastes. We mustadd to these local sources of pollution, domestic and industrial sewages coming from the NorthernIndustrial Zone of Dakar (canals VI and Vibis), from part of Dakar ("Front de Terre" canal), Bel Airand so on. All these waters are not treated.

Even if the sewage canalizations of the Dakar harbour don't end in the bay, oceanographic studies inthe bay have demonstrated a source of pollution coming from the harbour. The harbour receives thesewages of five main industries: SONACOS (peanut oil industry), SAF and NSOA (soap industries),MTOA (tobacco factory) and SOBOA (brewery).

Indicators

Measurements made in the bay indicate that some industries reject products with BOD7 up to 5,400mg O2 per l, COD8 up to 9,000 mg O2 per l and concentrations in chromium and suspended mattersrespectively of 7,400 and 3,000 mg.l-1 (Niang, 1992). For the rejects of the canal VI that is used forurban sewage, the BOD and COD values were respectively of 2800 and 6000 mgO2 per l while totalazote and total phosphorus concentrations were respectively of 490 mg N per l and 150mg P per l.(Fall, 1993).A previous study made for the Direction of Environment in 1986 indicated the following numbers fora number of parameters of chemical pollution (Table 12; in Sarr, 1993).

7 BOD: biological demand in oxygen8 COD: chemical demand in oxygen


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Table 12. Pollutants (in Tons by 100 Square Meters) Entering the Hann Bay from DiverseEconomic Activities (in Sarr, 1993)

BOD COD Oil, grease PhenolsNitrogenoussu

bstancesPhosphates

11,200 29,250 4,164 4.6 25.5 115

3.3.2 Environmental Impacts

The main impacts of the chemical pollution in the Hann bay are evidenced in different components ofthe bay.

3.3.2.1 Water Quality

A study made in 1990 by the Pluridisciplinary team of study of coastal ecosystems (EPEEC) showedin this bay (l’une à la verticale de Thiaroye, la seconde à la verticale du village de Hann et la troisièmeà la verticale du centre de pêche sportive « Marinas » (voir carte)) concentrations in chlorophyllecomprised between 9 and 20 _g.l -1 that is 18 to 40 times the values observed in the Bay of Yoff (about0,48 _g.l -1). This illustrates the level of eutrophication due to the organic matter rejects that feed thephytoplanktonic production in a context of very low hydrodynamism.

Relative to the bacterial contamination, total germs varied between 800 and more than 10 000 per 100ml of samples; Escherichia coli, between 0 and more than 10 per 100 ml; coliforms withconcentrations higher than 100 per 100 ml; enterocoqs with concentrations comprised between 0 andmore than 100 per 100 ml like Staphylococcus aureus. We can notice here the presence of germsindicative of a faecal contamination:

• proliferation of algae (Ulvae sp.) due to the important quantities of phosphated andnitrogenous substances that have a fertilising action leading to eutrophication of waters; and

• benthos.

From transects 1 to 3 and at a depth of 2 m, the sediment was a shelly clayey fine sand more or lesscovered by floating algae. In the transect 2 it was noticed that between 4 and 10 m, the sand was moreclayey with numerous red and green algae as well as numerous nudibranchs but without Pitar tumens.The transect 3 was characterized by the presence of many ulvas at a depth of 2 m. Moreover, for these3 transects a decrease of specific richesse towards the coast was observed, in direct link with thedegradation of natural conditions. Most of the molluscs, gastropods and bivalves encountered offshorewere made of young, this zone constituting a nourishing area. Numerous isopods in liaison with theabundance of vegetation were observed. The presence of ascidies, that belong to the genusHartmeyera, living on smooth grounds, traduce an important influx of organic matters. The Pitarfound in the sediment, are extremely infested by faecal coliforms (760 /g). This shell is collected andcommercialized but fortunately it is always cooked. What was surprising was the very lowcontamination of ascidies sampled in front of the Marinas (EPEEC, 1990);

3.3.2.2 Fishes

Mainly young and small species are present in these protected bays with a considerable amount offood. The ichthyologic component was composed of the following families:


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• Clupeidae (Sardinella sp, Sardinella aurita);

• Hemiramphidae (Hemiramphus brasiliensis);

• Serranidae (Dicentrarchus punctatus);

• Carangidae (Decapterus rhonchus, Campogramma glaycos);

• Gerreidae (Eucinostomus melanopterus);

• Haemulidae (Parapristipoma octolineatus);

• Sparidae (Sparus caeruleostictus, Pagellus bellottii, Boops boops, Diplodus sargus,Diplodus bellottii);

• Mugilidae (Liza sp);

• Sphyraenidae (Sphyraena sp);

• Acanthuridae (Acanthurus monroviae);

• Scombridae (Scomberomorus tritor, Euthynnus alleteratus);

• Soleidae (Solea sp);

• Cynoglossidae (Cynoglossus senegalensis); and

• Cichlidae (Tilapia sp, Tilapia guineensis).

So, in 1990, about 22 species belonging to 13 families were observed. This population is close,quantitatively, to those observed in less populated area. The main difference is the chemical andbacterial contamination (Niang, 1993). The demersal species are generally more contaminated thatpelagic species. The demersal fishes collected offshore the Marinas as well as off the Hann villagepresented concentrations of 500 Staphylococcus aureus per gram of fish (the norm being no more than100 Staphylococcus aureus per gram). Contamination by heavy metals is evidenced by copperconcentrations of about 20 mg per 100 g in the omnivorous fishes (Eucinostomus melanopterus),chromium concentrations of about 10 mg per 100 g in carnivorous fishes and of cadmium of about 1.2mg per 100 g in carnivorous (Euthynnus alleteratus) and plankton-eating fishes (Sardinella aurita)(EPEEC, 1990).

A survey of the ichthyoplankton repartition in the different bays of Dakar, made in 1992, observedclose to Thiaroye and in surface waters the presence of larva belonging to only one fish family(Blennidae) and an of about 5 per m3. In deep trawling (3.2-3.4 m), no species was present and the eggdensity was zero (Niang, 1992). Pandare et al. (1992) indicated the presence of dead larvae andembryos between Thiaroye and the Port of Dakar. This demonstrates the difficulties for the fishes toreproduce in this zone that was originally a good place for reproduction due to the weakhydrodynamism.

3.3.3 Socio-Economic Impacts

The more obvious consequences of the chemical pollution in the Hann bay are observed in the humanhealth.

Pollution, whatever its origin has consequences on human health in the Bay. From data collected withthe responsible for health of Hann sur mer, the more frequent diseases linked to the pollution of theHann Bay are:

• water diseases (bilharziosis, low occurrence);

• diarrheic diseases (cholera between 1995 and 1996);

• intestinal parasitosis (ascaris, ankylostome, ténia, oxyures…);

• skin diseases (scabis between 1990 and 1995);


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• eyes diseases (conjunctivitis during proliferation of flies on the beach); and

• pulmonary diseases (tuberculosis, bronchitis) (IAGU, CUD, CNUEH, PGU, 1997).

Till the 1970s the Hann bay was intensively used for recreational activities (swimming in very quietwaters, clam collect, fish market) but with the pollution now, most of the people have deserted thisbeach that is close of Dakar. However, local people and specially children still continue to swim inthese polluted waters with consequences for their health.

Other economic consequences of the chemical pollution of the Hann bay have been:

• the impossibility for industrial fisheries and conservatries to use the seawater to wash thefishes determining an over cost due to the use of potable water;

• the difficulties for industries like ICS to use seawater for cooling purposes due to the highpresence of microorganisms and algae which sometimes disrupt the process and apparatus;

• the impossibility to use beach seines specially due to the presence of algae but also to therarefaction of fishes. Moreover, fishermen need to go further offshore to fish; and

• the bad conditions of the fish market, installed in a polluted environment as well as the badsmelling of the fishes discouraged a lot of people to come to this market to buy fish.

It is important to notice that another place where chemical pollution is supposed to take place is theMboro beach, on the North Coast. On this beach, the ICS directly reject their fluoscilicic acid (Fall,1993).

In the Sénégal delta, pesticides and artificial fertilizer used in the CSS sugar cane fields close toRichard Toll but also in the irrigated fields are contaminating the soils and the waters even if the lackof monitoring doesn't allow knowing precisely what is the degree of pollution. The pesticides are alsoutilized in the Sénégal valley to fight against birds, locusts and rodents that destroy the cultivations.Recently, Ba et al. (1995) indicated nitrates concentrations up to 100 mg.l-1 in the phreatic groundwaters of the delta.

Indicators

Concurrently with the traditional indicators of chemical pollution, it seems that the ratiopolychetes/molluscs in the benthos can be considered as an indicator, the number of polychetesincreasing with the organic matter (Seck, 1993).

3.4 Socio-Economic Impacts Obtained with the Giwa Scoring Methodology

Socio-economic scoring of all hot spots and sensitive areas that were identified was achieved usingGIWA methodology (Table. 13 and 14). These tables show that the socio-economic score is the samewhatever we have a hot spot or a sensitive area.

The ratios indicate that if health losses are low, costs incurred are moderate, the reversibility ofdamages still have a very high score, with the exception of the Djoudj Park. The low value of thisindicator in the Djoudj is due to the fact that it is a protected area, where demographic pressure iscontrolled.

These results are mainly due to the methodology used. This is why we consider that it is useful to lookcarefully at this methodology in order to improve it. The following comments can be made.

• Costs incurred: in the methodology, these are deduced from the Gross National Product interms of purchase power parity (PPP) expressed in international dollars in the receptor areaand by habitant. We first determined this value for the all country, then we tried to determineit by administrative region considered as receptor area. We used the data of the 1992


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"Enquête sur les Priorités du Sénégal ». We thus obtained the GNP by region. We thus triedto improve the methodology. However this arose some questions like: what are the physicallimits of the receptor area? Is it appropriate to assimilate them to administrative entities?Moreover, from the three indicators proposed by the methodology, two of them are relativeto the receptor area (costs incurred and health losses). Hot spots and sensitive areas canbelong to the same receptor area (that was our case) and in this case the only difference thatcan be applied to these zones is the reversibility of damage indicator;

• health losses: we used the 1998 death rate per 1000 people (World Bank data) to determinethe average annual number of deaths for each receptor area. This indicator poses anotherproblem linked to the relationship between the factor responsible (pollution for instance) andthe rate of morbidity or mortality. How far are they linked? Moreover, to precise thisindicator, it will be necessary to have demographic and heath surveys; and

• reversibility of damages: this last indicator traduces the demographic pressure. It is highbecause of its composition. With a rate of growth rate very high (2.7%) and a highconcentration of populations along the coastal zone, it is obvious that Sénégal will have ahigh score.


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Table 13. Socio-Economic Scores as Deduced from GIWA Methodology: Hot Spots

Costs Incurred Health Losses Reversibility Of DamagesSocio-

EconomicScore

ReceptorArea

GNP, PPP19989

GNPPer

Capita

LowerThreshold

UpperThreshold

M1 ScoreCrudeDeathRate10

Aver.Annual Nbr

of CasesM2 Score Source Area M3 Score

Sénégal 15437 x 106 1708 1537225 6148902 1708 2 12.7 711 712 2 Djoudj 0.0559 1 3.5Delta dufleuve

510802216 1365 1228743 4914972 1365 2 29 29 1 Mbeubeusse 4132 3

Dakar 2319078327 1071 964137 3856549 1071 2 170 170 1 Cambérène 4132 3Saloum 1169770524 706 635521 2542084 706 1 130 130 1 Hann 4132 3

Casamance 787809120 1523 1371053 5484215 1523 2 41 41 1 Rufisque 2815 3Joal 507.5 3

Djiffère 90.25 3Dakar 40758.7 3

System ofscore

2 2 3

9 GNP, PPP (current international $) 199810 Crude death rate per 1000 pop, interpolated


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Table 14. Socio-Economic Scores as Deduced from GIWA Methodology: Sensitive Areas

Costs Incurred Health Losses Reversibility of DamagesSocio-

EconomicScore

ReceptorArea

GNP, PPP199811

GNP PerCapita

LowerThreshold

UpperThreshold

M1 ScoreCrudeDeathRate12

Aver.AnnualNbr ofCases

M2 Score Source Area M3 Score

Sénégal 15437000000 1708.0 1537225 6148902 1708.0 2 12.7 711.6 711.6 2 Delta du fleuve 135.2 3 3.5Delta dufleuve

510802216 1365.3 1228743 4914973 1365.3 2 29.5 29.5 1 Mboro 254.8 3

Dakar 2319078327 1071.3 964137 3856550 1071.3 2 170.5 170.5 1 Lac Retba 360.8 3Saloum 1169770524 706.1 635521 2542084 706.1 1 130.4 130.4 1 Soumbedioune 321.8 3

Casamance 787809120 1523.4 1371054 5484216 1523.4 2 40.7 40.7 1 Mbao 2815.4 3Thies 1957914312 1576.0 1418403 5673611 Casamance 183.2 3

Saloum 177.4 3

System ofscore

2 2 3

11 GNP, PPP (current international $) 199812 Crude death rate per 1000 pop, interpolated


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CHAPTER 4

4. Causal Chain Analysis

The following causal chain analysis is presented by issues. However, for root causes, as they arecommon to all the issues, they will be considered in a separate chapter. The methodology proposedwas strictly followed, thus natural causes were not analyzed as well as immediate causes responsiblefor less than 30% of the issue. When common, the immediate or sectoral causes were described once.

4.1 Issue 1: Modification of Stream Flows

Two types of modifications of stream flows were considered in the impact analysis: transformations ofwater quality due to damming encountered in the Sénégal river and "reverse" estuaries observed in theSaloum and Casamance rivers.

The transformation of the Saloum and Casamance estuaries in reverse estuaries is a situation that ispurely natural, due to the impacts of the drought. For this reason, it will not be analyzed.

4.1.1 Sénégal River

4.1.1.1 Immediate Causes

The modifications actually observed in the Sénégal river regime are attributed for 100% to thedamming of the river.

The Diama dam located about 50 km from the mouth opened in 1986. Its main function was to stopthe seawater intrusion that penetrated till 250 km upstream (Gac et al., 1986). It is 34 m long with 7gates and a freshwater reservoir of about 250 million of cubic meters with a potential area of 340 km2

at an altitude of 2.5 m. The freshwater made available was supposed to be used to irrigate about240,000 ha of land and to insure the correct infilling of the Guiers lake thus allowing an appropriatesupply of drinking water for the capital, Dakar. The building of a dike on the right side of the valleyand the rehabilitation of the dike on the left side were made to increase the capacity of the reservoir to585 millions of m3 and its area to 435 km2.

4.1.1.2 Sectoral Causes

The decision to build two dams (Diama and Manantali) on the Sénégal river was to solve two mainproblems closely linked to the drought and its impacts: availability in arable lands and water supply.The other two objectives assigned to these dams were the navigability between Saint-Louis and Kayesand the production of hydroelectricity. Thus we considered that agriculture was responsible for 60% ofthe cause, water supply for 30%, fluvial transport and energy production each for 5% (Figure 17).

Agriculture Sector

During a long period agriculture was the first economic sector in Sénégal and was characterized by aquasi monopolistic of peanut production. Impacts of the drought combined with inadequateagricultural practices induced a general degradation of the soils particularly in the "peanut basin"(regions of Thiès, Diourbel, Kaolack and Fatick) where most of the peanut was grown. The persistenceof the drought weakened the peanut production that is strictly dependent on rainfall despite thenumerous efforts to develop drought resistant cultivars. In the Sénégal valley, agriculture, mainlydeveloped in the flood prone areas ("waalo"), was compromised due to a constant decrease in the riverdischarge (Olivry, 1983; Handschumacher et al., 1992). At the same time, populations, especiallyurban populations, consumed more and more rice while 86% of this rice is imported, mainly fromThailand (Devey, 1997). Rice grown essentially in Saloum and Casamance estuaries where increased


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salinities in soils and waters considerably hampered this crop. Sadio (1991) indicated that about230,000 ha and 400,000 ha of soils were affected by salinity respectively in the Saloum andCasamance river basins. In the Senegal River basin, the same author estimated that 400,000 ha of soilswere affected by salinisation. It was thus decided to build the two dams under the control of OMVS13.One of the objectives was the development of irrigated crops, mainly rice. It must be recalled that thefirst tests of irrigated riziculture in the Senegal delta were made in 1945 in Richard-Toll (Niang,2000).

Actually, the results are far from what was expected. In 1996, only 60,000 ha of lands were irrigated inthe Sénégal river basin (République du Sénégal/Ministère de l’Environnement, 2000). This situation ismainly due to the fact that most of the peasants don’t have the financial resources to face the highinvestments necessary for the equipments. The rice production declined from 1994 (130,615 tonnes) to1996 (85,334 tonnes) mainly due to the fact that the rice produced is not competitive with the importedrice (Devey, 1997).

Figure 17. Causal Chain Analysis for Modification of Stream Flow: The Sénégal River(yellow is for the issue considered; green for the immediate causes level; red for the sectoral level

and pink will indicate links between issues)

Water Supply

The second main objective of the Diama dam was to ensure water supply especially for Dakar. Since1971, part of the water used in Dakar (20% in 1980) comes from the Guiers Lake where the NgnithStation pumps and treats the water before sending it through a 250 km long big pipe (Wane, 1983).This system was threatened by the seawater intrusion in the Sénégal river contaminating the Guierslake.

Actually, this objective of the dam is fully attained since lake level raised (Cogels et al., 1993) and asecond pipe was emplaced. However, it must be noted that the non-realisation of the Cayor Canalproject14, mainly due to the lack of funding, didn’t allow a full use of these waters (Niang, 2000).

Fluvial Transport

Another objective of the dams was to ensure the navigability of the river between its mouth and Kayes(940 km upstream in Mali). The continuous decrease in the river discharge reduced considerably theuse of the Sénégal River for transport and trade since 1972. The establishment of a stable river

13 OMVS: Organization for the Management of the Senegal basin. Created in 1972 with Sénégal,

Mauritania and Mali, it is a sub-regional structure encharged of the management of the Sénégal hydrographicbasin.

14 The Cayor Canal Project was designed to bring water from the Guiers lake to Dakar and Thies regionsfor domestic purposes, hydro-agricultural activities and the refilling of aquifers.

Agriculture60%

Water supply30%

Fluvial transport5%

Energy production5%

Damming of the river100%

Issue 1Modification of stream flow

Sénégal delta


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discharge (300 m3.s-1) in Bakel allows the resurgence of this activity. Actually, OMVS is encharged ofthe navigability between Saint-Louis and Kayes while the COSEC15 will consider the building of anew harbour in Saint-Louis as well as the access from the sea. A feasibility study is just beginning(launched the 26th of September 2001).

Energy Production

61% of the energy used in Sénégal comes from forest products (either fire wood: 1,5 million of tonnesor carchoal: 330,000 tonnes per year) followed by petroleum (37%) that is mainly imported. Since1981, different strategies have been developed to try to change this structure of the energyconsumption (Devey, 1997). The use of hydropower produced by the Manantali dam is part of thisstrategy. The OMVS previsions were to ensure a production of 800 GWh per year of hydroelectricity,33% being allocated to Sénégal. Actually, it is considered that this contribution will begin next year.

4.1.1.3 Responses

Due to the specificity of the problem (big dams under the control of a sub-regional organization),responses have been mainly at the governmental or sub-regional levels since communities and marketcan’t do much in this case. In fact the building of these two dams has been presented as a "State affair"and despite the different reserves that were presented - mainly by research structures- it has beenconsidered that positive effects of the dams (new lands for irrigated agriculture, water availability,hydroelectricity) will be far more important than negative impacts. However, the environmental andsocio-economic consequences of the dams (as described in the impact analysis) more or less forced theauthorities and the OMVS to respond. In this sense, we identified the following responses dependingon the level considered.

At a national level:

• special attention to research activities and monitoring: numerous programmes have beendeveloped in the Sénégal river basin to try to understand the changes in order to minimizethem. The main research institutes involved were the Centre for Oceanographic Research(CRODT) that is dependent on the Ministry of Agriculture, the Institute for InternationalResearch (IRD) and the Universities. A geographical information system for themanagement of the Guiers lake was developed (Niang, 2000); and

• recently a programme to remove Salvinia molesta from the delta was initiated. In a firstphase and for a total cost of 50,000 US$ (funded by UNDP-FEM microproject) theGovernment of Sénégal with an NGO ("Diapanté") was able to clean 39,000 m2 (about 4 ha)of areas infested, specially those close to the small dams and pumping stations(CCMAD/DIAPANTE, 2001). However, about 30 ha of waters are still infested and it hasbeen decided to use biological agents (insects) to try to solve this problem. A study indicatedthe possibility to transform the invasion of Typha in biomass charcoal (Matera and Malaisse,1999). From the first evaluation, it was deduced that 40,000 tonnes of charcoal could beproduced only from this plant.

However, there is still, at a national level, a lack of coordination between the different institutionsencharged of the water management in the delta (SAED16, Ministry of Hydraulics, Ministry of theEnvironment, …).

At a sub-regional level:

15 COSEC: Senegalese Council of Shippers.16 SAED: Society for the Management and Exploitation of the Delta, encharged of surface waters management since 1970.


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• in 1997, the OMVS created two societies encharged of the management of the two dams: theSociety for the Management and Exploitation of the Diama Dam (SOGED) and the Societyfor the Management and Exploitation of the Manantali Dam (SOGEM). Real managementproblems exist and induced inundations in Saint-Louis region due to the fact that gates of theDiama dam were opened too late; and

• moreover, the OMVS launched a Programme for an optimized management of the Diamaand Manantali reservoirs as well as a programme of mitigation and monitoring of theenvironmental impacts of these dams.

4.1.1.4 Transboundarity Issues

In this case, the transboundarity is obvious since the Sénégal river is an international river that iscommonly managed by a sub-regional organization, OMVS which is constituted by 3 riverinecountries: Mali, Sénégal and Mauritania. It is organized by a Convention that was signed the 11 march1972. Well experienced, it has been able to overcome different problems between the States (conflictSénégal-Mauritania, problems around the revitalization of fossil valleys).

Another aspect is that two parks located on each side of the Sénégal river - the Djoudj park in Sénégal(which is one of our hot spots) and the Diawling park on the Mauritania side - are closely linked andcould benefit from a common management or at least exchanges between the two countries.

4.1.2 Saloum and Casamance Estuaries

4.1.2.1 Responses

Even if the modifications of stream flow in these two estuaries have natural causes, it is important tojust note the efforts made, mainly by the populations and NGOs, to recover salted soils, in particular inthe Saloum delta. In Sénégal there is a long tradition (since 1940) to recover salted soils, mainly bybuilding anti-salt dikes that are made to retain runoff waters in order to grow rice and afforestation tostop Aeolian erosion and stabilize the soils. Of course, these operations are costly but there are indicesthat these techniques can be successful. In the Saloum delta, such initiatives allowed rice growing afterthat crop has been abandoned.

In Casamance, some of these experiences have been negative and have been abandoned (Guidel mini-dam) (Diop, 1986);


The Saloum delta park has a common border with the Niumi National Park located in The Gambia.Recently, there have been agreements relative to the common management of these two nationalparks.

4.2 Issue 12-13: Modification/Destruction of Ecosystems

Due to time constraints we have not been able to address all the fragile ecosystems identified duringthe first phase. Only fish communities and mangrove-wetlands modifications were addressed.

4.2.1 Fish Communities

Modifications of these populations have been observed in the Hann bay, in the estuaries but also onthe Southern continental shelf. These degradations are mainly due to a degradation of reproductionand nursery grounds. For immediate causes, we examined each site separately. Then, sectoral causeswill be analysed together since they are common.


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Hann bay

In the Hann bay what has been observed was:

• the quasi - disparition of benthic species (Niang, 1992; Pandare et al., 1992);

• the temporary presence of juveniles pelagic;

• the presence of dead larvae and embryos indicating the difficulties of reproduction in a zonethat was formerly highly used for reproduction; and

• the contamination of demersal species by bacteria (Staphylococcus aureus) and heavy metals(mainly copper, chromium and cadmium) (EPEEC, 1990; Niang, 1993).

The immediate causes of these modifications have been identified as chemical pollution (40%),overfishing (40%), eutrophication (15%) and sonorous pollution (5%) (Figure 18).

Figure 18. Causal Chain Analysis for the Modification of Ecosystems: Fish Communities in theHann Bay

Chemical pollution will be analysed further on. The main effect of chemical pollution is to destroyjuveniles and thus interrupt the life cycle of the species (Gningue, 1995). The industrial pollution isalso considered as the main responsible for the destruction of benthic species in the bay (Niang, 1992;Pandare et al., 1992). Another consequence of pollution is the contamination of fishes.

Overfishing seems to be the result of extensive use of beach seines along the bay. This fishing methodhas the main disadvantage to trap all the marine species present without any distinction of size. Thisfishing method is no longer used and fishermen are now obliged to go further offshore to fish.

Eutrophication is a consequence of the chemical pollution. It is evidenced by algal blooms. The mainproblem of this form of pollution is the non-avaibility of oxygen that impede most of the fish speciesto live, reproduce and grow in these waters. As a consequence, the only species that are still presentare mullets (Liza sp.) and tilapias (Sarotherodon sp.).

Sonourous pollution is due to the motorized boats that cross the bay, belonging either to fishermen oryachtsmen that are located in the marina. The noise is considered to disturb fishes when they come inthe bay to reproduce.

Link with Issue 6

Industry70%

Energy supply30%

Chemical pollution40%

Link with issue 14

Fishery sector70%

Agriculture15%

Urbanization10%

Tourism5%

Overfishing40%

Link with issue 5

Eutrophication15%

Sonourous pollution5%

Issue 12-13Modification of ecosystem

Fish communities - Hann bay


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Estuaries

Due to the two different types of estuaries in Sénégal, we considered separately the Sénégal delta andthe Saloum and Casamance estuaries.

Sénégal Delta: an "Artificial" Estuary

In this case, the modifications of the fish communities are linked to the strict separation between thedownstream part of the Diama dam with mainly salted waters and the upstream part with freshwaters.No more exchanges are possible between these two compartments, except during the opening of thegates.

The immediate causes are the presence of the Diama dam (60%) and the over-exploitation of fishresources (40%) (Figure.19).

Figure 19: Causal Chain Analysis for Modification of Ecosystems: Fish Communities in theSénégal Estuary

The Diama dam and its characteristics were described for the precedent issue (Issue 1).

Overfishing is identified as a second cause for the modifications of fish communities. There areindices of over-exploitation of the estuarine resources especially with the onset of the drought in thebeginning of the 1970s. Due to the difficulties to ensure food security with agriculture there have beenpressures on the estuarine resources. For shrimps (Penaeus duorarum notialis) there were contradictoryappreciations about the exploitation of the stock (Diouf and Bousso, 1988).

Saloum and Casamance: Inverse Estuaries

In these estuaries, the main modifications observed in the fish communities were:

• a penetration of marine species in the downstream part of the estuaries; and

• development of monospecific communities in the hyperhaline parts of the estuaries (mainlySarotherodon melanotheron).

These modifications have been attributed mainly to an increase in salinity (45%), overfishing (40%)and degradation of mangroves (15%) (Figure.20).

Agriculture60%

Water supply30%

Fluvial transport5%

Energy supply5%

Damming of the river60%

Fishery sector70%

Agriculture15%

Urbanization10%

Tourism5%

Overfishing40%


Fish communities-Senegal delta


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Figure 20. Causal Chain Analysis for the Modification of Ecosystems: Fish Communities in theSaloum and Casamance Estuaries

The increase in salinity of these estuaries was described in the impact analysis. It is a naturalphenomenon due to the drought that considerably reduced freshwater inputs, thus allowing seawater tointrude very far in the rivers. The high evaporation rates observed in Sénégal induced a concentrationof sea waters leading to salinities up to 170%o 200 km upstream of the mouth.

Like in the Sénégal delta, overfishing was observed in these estuaries for the same reasons.

Degradation of mangroves contributed quite a lot in the modifications of fish communities becausethey are important breeding and nursery grounds for many fish species. Due to the drought andincrease in salinity they have been subject to a degradation process, being progressively replaced bybarren areas, the "tannes". This process was particularly developed in the Saloum estuary and in theupstream reaches of the rivers.

Southern Continental Shelf

Modifications in the composition of the fish communities present on the southern continental shelfwere attributed for 100% to overfishing (Figure. 21).

Figure 21. Causal Chain Analysis of the Modification of Ecosystems: Fish Communities on theSouthern Continental Shelf

Strong evidence of overfishing was mentioned by Barry-Gerard et al. (1993), especially for demersalspecies. A report from the Ministry of Agriculture (1995) clearly indicates overfishing on the southerncontinental shelf specially in depths less than 60 m. Between 1986 and 1991 a decrease of about 50%in the abundance of demersal species has been estimated (Ministère de l’Agriculture, 1995). The main

Link with issue 12-13

Degradation of mangroves15%

Natural100%

Increase in salinity45%

Fishery sector70%

Agriculture15%

Urbanization10%

Tourism5%

Overfishing40%

Issue 12-13Modification of ecosystems

Fish communitiesCasamance-Saloum estuaries

Link with issue 14

Fishery sector70%

Agriculture15%

Urbanization10%

Tourism5%

Overfishing100%


Fish communities on the South continental shelf


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species concerned are Galeoides decadactylus, Arius spp., Sparus coeruleostictus, Epinephelus spp.,Cynoglossus spp., Plectorhynchus mediterraneus and Pseudupenaeus prayensis. The same reportattributes this situation partly to an intense activity of Russian trawlers in the region and partly to anincrease in juvenile captures by artisanal fisheries. Parallely, between 1984 and 1991, the landings ofcoastal pelagics increased from 110,000 to 223,000 tonnes (more than a doubling).


For the three cases where modifications of fish communities have been observed, the main immediatecauses were: chemical pollution, river damming, overfishing and increase in salinity. The sectoralcauses of chemical pollution will be analyzed in the next causal chain analysis. Those responsible forriver damming have already been addressed (see issue 1). Increase of salinity is a natural phenomenon.We will thus examine only the sectoral causes of overfishing.

Overfishing is a common immediate cause for the modification of fish communities. It is also a majorGIWA issue. In the first phase of the process (scoring and scoping), this issue was ranked 4th and thuswas not considered further on. The fact that it comes again with this analysis of the modifications infish communities indicate that although not considered as such, it is still an important issue. Thisanalysis is also an example of links between two different issues: modification of ecosystems andoverfishing (see Figures 2 and 4).

Overfishing is off course stongly linked with the fishery sector (70%). However we also consideredthat agriculture, urbanization and tourism contributed respectively to 15, 10 and 5% to this cause.

Fishery Sector

As indicated in chapter 1, fishery is a major sector in the national economy, being the first in terms ofexport earnings. This development of the fishery sector began in the years 70s when fisheries seemedto be an alternative to agriculture whose first objective was to achieve food security. At the same time,peanut oil suffered from competition with other vegetable oils while phosphates experienced a generaldecline in the prices of the world market (Prescott, 1993). It is during these years that Sénégalexperienced a severe drought inducing an important decrease in the agricultural yields together withland abandonment, death of cattle and people. Thus, the government decided to initiate policies inorder to encourage the development of artisanal fisheries: motorization of the boats, fuel subsidies17,facilities for credit access, and construction of infrastructures18.

There have been also exportation incentives, representing 1.2 billion CFAF in 1993 (Ministère del’Agriculture, 1995), in an international context favouring fish exportation. Following the 1982 Lomeagreements, customs dues at the entry of European market were suspended for fish exportationscoming from ACP19 countries. This was a compensation for fishing agreements between the EuropeanCommunity and these countries.

The devaluation of the CFA Franc in January 1994 reinforced the pressure for exportations sinceprices are more attractive on the foreign market than on the local market. A marked increase in the fishexportations was noted between 1993 and 1995 (JICA/MPTM, 1997) (Table.15). About 60% of theexportations go in Europe followed by Africa (30%) and Asia (10%). It was also observed priceincreases of more than 90% for export products (Ministère de l’Agriculture, 1995).

17 They represented 4 bilions of CFAF in 1992 (Ministère de l’Agriculture, 1995)18 The PAPEC (Project to assist artisanal fisheries on the Petite Côte), created in 1987 with BAD funding built fishinfrastructures (quays and transformation aeras) in Rufisque and Joal for a total amount of 1511 million of CFAF(JICA/MPTM, 1997)19 ACP African Caraibes and Pacific


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Table 15. Evolution of Fish Exportations Between 1992 and 1997 (JICA/MPTM, 1997)

1992 1993 1994 1995 1996 1997Exports (tonnes) 91,257 83,822 104,658 103,465 107,079 112,048

At the same period a translation of fishing efforts towards species more valued overseas (cephalopods,soles) was observed (JICA/MPTM, 1997). Bas (1993) indicated a high pressure on octopus butmitigated by rapid turnover rates of this genus. It is also noticeable that the exports to Ghana aremainly constituted of small fishes (less than 5 cm in size) that is an incitement to overfishing.

This orientation of the economy towards exportations was confirmed by the IXe Plan (République duSénégal/MEFP, 1997).

Agriculture Sector

It is considered to be responsible for 15% of overfishing just because, due to the drought, somefarmers converted in fishermen. The small fishing villages of Lompoul and Fass Boye, along theNorth Coast, are partly constituted of former farmers (JICA/MPTM, 1997). Also, due to the reductionin crop production, there were more pressure on the halieutic resources to compensate the losses inproteins. This was particularly observed along the Sénégal river.

Urbanization

The rate of urbanization is relatively high (40%) and since most of the urban areas are located alongthe coast, there has been more pressure on the fishing resources. It has been observed that Dakar, forexample, consumes 39 kg of fish per inhabitant and per year in 1989 while in continental areas likeTambacounda the consumption was of 8.4 kg per inhabitant and per year.

Tourism

Tourism induced a high demand on fish, crustacean and molluscs and was thus considered tocontribute for about 5% of overfishing. This is particularly true because restaurants request forexample small fishes more convenient for the client. Thus big fishes like the groupers (Epinephelusspp) are captured too young.

4.2.1.3 Responses

Governmental Responses

Regarding overfishing, the governmental responses are mainly oriented towards modifications in thefishing agreements with the European Union. This agreement is still in discussion and it is prematureto predict anything on the results.

Efforts have also been made, with the new fishing law (law 98-32 of the 14 April 1998), trying toregulate the mesh sizes or the authorized size for the fishes but also encouraging period of biologicalrest. But the control of the level of implementation of this law is still a problem. Efforts are howeverdone like the project "Protection and Monitoring of Fisheries in Senegal" (PSPS) created in 1981 withthe help of Canada and that costs annually 500 million of CFA F to the State budget (JICA/MPTM,1997). This project is actually organized in 6 control offices with a total of 11 inspectors and 80observers that is still limited.

Sénégal also belongs to the Fishery Committee for the Eastern Central Atlantic that has mainly a roleof recommendations addressed to the governments to better manage their fisheries. Among otherthings, this committee works on the fish stocks in the sub-region.


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Community Response

The fishing communities are of course aware of this over-exploitation but there are also pushed by thenecessity to find revenues.


Most of the halieutic resources, especially pelagics, are transboundary. In Senegal, part of the fishstock (mackerels, anchovies and by extension cephalopods like Octopus vulgaris) depend on thecoastal upwelling linked to the Canary current and thus migrate latitudinally between Morocco andSenegal.

Moreover, following the maritime boundary dispute between Senegal and Guinea Bissau, a commonexploitation of fish resources located in the disputed area was decided (Prescott, 1993). A bilateralagency was created to manage this resource as well as oil resources. However there are still problemswith Mauritania and quite frequently Senegalese ships are arrested creating tension between the twocountries.

4.2.2 Mangrove and Wetlands Ecosystems


As indicated in the impact analysis, the degradation of these ecosystems is mainly (70%) aconsequence of the modification of stream flows either due to the drought (Saloum and Casamancerivers) and/or to river damming (Sénégal river). Another cause of this degradation is the over-exploitation of resources (for about 30%) (Figure 22).

Figure 22. Causal Chain Analysis for Modification of Mangroves and Wetlands

Note that the two main immediate causes of the degradation of wetlands and mangroves are in factenvironmental issues as defined by GIWA (Issues 1 and 14).

As the "modification of stream flows" issue was previously examined, we consider that the samecausal chain analysis can be applied. Although it affected the two ecosystems, this issue is mainly ofconcern for wetlands.

Link with issue 14

Fisheries40%

Energy50%

Others10%

Overexploitation of resources30%

Link with issue 1

See Issue 1 causal chain

Modification of stream flows70%

Issue 12-13Modification of ecosystemMangroves and wetlands


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The over-exploitation of resources in these ecosystems can be attributed mainly to energy (for 50%)and fishery (for 40%) sectors, the other sectoral causes being shared between the building andtransport sectors mainly.

Energy

Energy is a major source of degradation of many ecosystems in Sénégal because more than 53% of theconsumption and 94% of the domestic consumption are wood-based (either as charcoal or fuel wood)(République du Sénégal/Ministère de l’Environnement et de la Protection de la Nature, 1997a). Fuelwood is the main source of energy for most of the rural populations. Between 1937 and 1997, theofficial production of fuel wood in Sénégal increased from 23,925 to 143,967 steres (République duSénégal/Ministère de l’Environnement/Centre de Suivi Ecologique, 2000). At the end of the years 80s,the rate of deforestation was estimated to be 80,000 ha per year, 30,000 ha being used for firewood. Inmangrove areas, the trees are cut by the local populations and used for cooking and building houses(Ndiaye, V., 1995).

The energy sector in Sénégal faces a very difficult situation between an over-exploitation of woodresources and a dependency on petroleum importations.

Fishery

The main fishery activities leading to a degradation of the mangrove ecosystems is the collect ofoysters (Crassostrea gasar) that are on the roots of mangal trees, mainly Rhizophoracaea. This activityis mainly developed during the dry season by women and most of the time they directly cut the rootsinstead of removing the oysters. This is recognized as one cause of the degradation of the mangrovespecially on the bolon sides where the oysters are present. Studies made in Casamance (in Mbow,1997) have estimated the production between 1,000 and 10,000 tonnes per year, involving 2,000 to4,000 women. These studies give also indices of over-exploitation of this resource: reduction in thesize of the shells, more time is necessary to collect the same quantity of oysters, disparition of somebanks). This trend seems also linked with a shift from a domestic use to a commercial use, to obtainmoney, a trend that was also observed for the collect of bloody cockle (Anadara senilis) in the Saloumestuary (Descamps, 1994).

Other Sectors

The other sectors contributing to the degradation of mangroves in particular are the building sectorsince most of the traditional houses are built at least partly with mangal woods as well as the transportsector since a great number of "kjokkenmoddinger" have been destroyed to use the shells for roadconstruction in all this region.

4.2.2.3 Responses

Governmental Responses

In the energy sector, the Government of Sénégal is trying to progressively promote other sources ofenergy. The first initiative was the Programme of Energetic Redeployment of Sénégal (RENES)launched in 1981 with the aim to develop the use of natural gas, offshore petroleum (dome Flore inCasamance), mineral charcoal, hydroelectricity and peat. Numerous projects were developed for theuse of solar energy especially in rural areas. Subventions (representing 6 billion CFA F annually) werealso given for a butanisation programme to allow a substitution to charcoal, especially in urban areas.A lot of researches were also conducted on the design of more efficient stoves ("Sakhanal" stoves)with the collaboration of an University research centre, the Centre for renewable energies (CEREER).However, most of these projects failed due to different constraints (delays in the production of


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hydroelectricity by the Manantali dam, boundary dispute with Guinea Bissau, costs of theinfrastructures, insufficient reserves or non profitability). The new orientation towards privatizationdoesn’t seem to give appropriate responses for the energy sources in rural areas and it is foreseeablethat pressures on the natural resources will continue.

Over-exploitation of shellfish is not really a targeted issue partly because the situation is not fullyunderstood. The main governmental efforts that could contribute to reduce this trend are the promotionof a more sustainable use of resources. In the IX Strategic Plan (République du Sénégal/Ministère del’Economie, des Finances et du Plan / Direction de la Planification, 1997), this was recognized as oneof the orientation. The adoption of the National Environment Action Plan as well as the BiodiversityStrategy (République du Sénégal/Ministère de l’Environnement et de la Protection de la Nature, 1997aand b) constitute the legal framework from which to consider the development of sustainable use ofnatural resources.

As part of these governmental responses, the nature conservation policies must be considered. At thebeginning this policy was strictly conservative, protected areas being defined to cover a wide sampleof the different ecosystems. This corresponded with the establishment of the National Park directionwith a strong military orientation with the view to exclude populations from the use of the resourcespresent in the protected areas. The increasing difficulties to manage these areas without populations aswell as the shift realized by the international community towards more participative approachesinduced deep changes in this policy. Actually, the National Parks Direction is preparing managementplans for all the protected areas in Sénégal. First experiences of mutual benefit management of theprotected areas indicate that public awareness of the limitation of natural resources and the necessityfor a sustainable exploitation of these is increasing.

It is also important to recall that Senegal ratified the Ramsar Convention (11th November 1977) andthe Paris Protocol (15th may 1985). Actually, four protected areas, all located in the coastal zone, havebeen designated as Ramsar sites (the Djoudj Bird National Park, the special fauna reserves ofGueumbeul and Ndiael, the Saloum Delta National Park20) (République du Sénégal/Ministère del’Environnement et de la Protection de la Nature, 1997b). This Convention allowed the nationalauthorities to better manage specific protected areas. However some lawyers consider that it would bewise to elaborate a specific law for sensitive ecosystems like mangrove at a national level.

Community Responses

There has been a lot of projects that tried to initiate more sustainable of the resources. The IUCNproject of participative management of the Saloum delta National Park is a good example of projectsthat develop new technologies while explaining the danger of unsustainable use of resources to thepopulations.


The two main ecosystems (mangroves and wetlands) are present in two protected areas that are locatedclose to the boundary with our neighbours. The Djoudj Bird National Park has a common boundarywith the Diawling National Park that was created in 1991 by Mauritania. This park has a total area of15,000 ha. Further south, the Saloum delta National Park is in the samesituation with the NuimiNationalPark of Gambia. This situation can offer opportunities to develop true partnership with thesecountries for a sustainable management of these protected areas.

20 Note that the first three one are located in the Sénégal delta. The fourth one is in the Saloum estuary.


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4.3 ISSUE 6: Chemical Pollution

4.3.1 Immediate Causes

The main cause of chemical pollution in the Hann bay is the discharge of untreated industrial sewagesthat contribute to 60% of the issue. Discharge of domestic sewages is considered to contribute for 10%of the issue while discharge of pesticides will contribute to less than 1% of the issue. Then, watercirculation in the bay is responsible for 30% of the issue.

As indicated in the impacts assessment report, industrial sewage represent less than an half of theuntreated polluted waters discharged in the bay, the rest being constituted mainly of domestic sewages.However, it is mainly in industrial sewages that chemical pollutants are found (Table 16). All thesewaters are untreated and discharged directly on the beach or in the bay (Sarr, 1993). Such a situation iscommon in most of the big cities of the West and Central African region (Portmann et al., 1989).

Table 16. Comparison of Industrial and Domestic Sewage Composition(from Niang, 1993 and Fall, 1993)

Types of sewages BOD CODIndustrial 5,400 mg O.l-1 9,000 mg O.l-1

Domestic 2,800 mg O.l-1 6,000 mg O.l-1

Domestic sewages contain more biodegradable components (food residues). However, they alsocontain a lot of microbiological organisms (coliforms, Escherichia coli): more than 10,000 germs per100 ml of water were counted in the Hann bay in 1990 (Niang, 1993).

Although not monitored, pesticides should also contribute to the issue since there is a lot of marketgardening activities in the small lows present in the sector.

Water circulation is considered to contribute for 30% to the issue. In fact, the Hann bay is a swellprotected area due to its position just south of Dakar. An oceanographic survey made in 1973 (PNUD,1973), indicated that the bay was characterized by very weak currents (< 10 cm.s-1 with maxima of 30cm.s-1) mainly wind generated such that when there is no wind the bay can be considered as a stagnantwater body. A kind of cyclonic circulation was observed during rainy season and neap tides but alsoduring the dry season. However, the main conclusion of the study was that, due to the weakness of thewater circulation, it was suggested not to discharge sewages in the Hann bay because most of thematters able to settle could accumulate.

It is also important to consider that chemical pollution is only one aspect of the pollution in the Hannbay since other kinds of pollution are present:

• microbiological pollution that is essentially due to local populations and linked to thedeficiency/lack of sanitary systems; and

• solid wastes pollution, mainly by the fish wastes left on the beach close to the fishingmarket.

4.3.2 Sectoral Causes

With the exception of the water circulation that is a natural phenomenon, the main sector contributingto the issue is industry (70% of the industrial sewages), the rest coming from petroleum industry(30%) (Figure.23).


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Figure 23. Causal Chain Analysis for Chemical Pollution

4.3.2.1 The Industry Sector

It is considered that chemical pollution is mainly due to:

• the non treatment of industrial sewages;

• the concentration of industries along the coastal zone;

• the type of industries that are present; and

• the great age of the installations.

It was indicated in the presentation of the Sénégal coastal zone, that the region of Dakar concentrates90% of the industries and about three quarters of the employments, turnovers and added value (Devey,1997). Since 1950, industries have been concentrated in the "industrial zone" comprised between theDakar harbour (Bel Air) and the end of the Hann village and between the national road n°1 and thesea. In 1970, 400 factories employing about 17,000 workers were present in this zone (Seck, 1970). In1974, was created the industrial free zone of Dakar, an area of 650 ha (450 ha reserved for industrialunits) located between Thiaroye and Rufisque, in the continuation of the old industrial zone. That'smeans that before the independency, most of the industries were located along the Hann bay.

The industries present in the industrial zone are dominated by agribusiness (50% of the industrialsector turnover, representing about 805 billions of CFA F in 1993-94) and chemical industries (26% ofthe turnover). Agribusiness is characterized by the transformation of natural resources either local orimported (peanuts, cattle, fishes, tobacco). Oil and fish industries dominate and use a lot of chemicalpollutants in their process (i.e. ammonia and formalin). Chemical industries are dominated by theICS21 that produce phosphoric acid and fertilizers from the phosphates extracted in Taïba but whosemain waste is the fluosilicic acid. The textile industry, particularly the Icotaf and NSTS22, usesartificial colourings and is also characterized by obsolescent equipments (IAGU/CUD/CNUEH/PGU,1997a).

However, more than the concentration of all these industries along the Hann bay, the main problem isthat the industrial wastes are not treated before being discharged in the sea. Despite the existence ofregulations, most of the industrials prefer not to use non pollutant processes because the authoritieshave many difficulties to exert their control on the industrial wastes but also because penalties are solow that they prefer to pay instead of invest in clean technologies or treatment processes (Sylva andBen Arrous, 1998).

21 ICS: Chemical Industries of Sénégal22 NSTS: New Society of Textile of Sénégal

Discharge of domestic sewages10%

Natural100%

Circulation in the bay30%

Industry70%

Energy30%

Discharge of industrial sewages60%

Issue 6Chemical pollution


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4.3.2.2 The Petroleum Sector

The production of hydrocarbons, very low (less than 1000 tonnes of crude oil and about 20 millions ofm3 of natural gas), is under the responsibility of Petrosen23. However, Sénégal imports most of itsproduction (900,000 tons of crude oil in 1996 for a total of about 92 billions of CFA F paid in US $).The only oil refinery in the country is the SAR24 that is located close to Mbao, again along the Hannbay. It is characterized by the obsolescence of its equipment, in particular - and it is important for thepollution of the Hann bay - the pipes where crude oil is transported from the tankers staying offshoreto the refinery.

The contribution of the Dakar harbour through unballasting must be added as contributing to thepollution by hydrocarbons as well as the small garages that discharge used oil changes.

4.3.3 Responses

The pollution of the Hann bay is a very well known example of the environmental degradation inurban areas. Since a long time it has been identified as such and a lot of workshops have beenorganized to try to find a solution to this major problem.

4.3.3.1 Governmental Responses

Senegal has ratified some international or regional conventions that are of concern for the chemicalpollution of marine waters. These are:

• the London International Convention for the prevention of marine waters pollution byhydrocarbons, signed the 12 may 1954 (with amendments in 1962) and ratified in 1972 (law72-17 of the 1 February 1972); and

• the Abidjan Convention on cooperation relative to the protection and improvement of marineenvironment and coastal zones of West and Central Africa, signed the 23 march 1981 andratified the 5 august 1984 (law 82-21 of the 23 July 1982). This regional convention definesin its articles 5 to 9 the rules for all kinds of marine and coastal pollution.

Under the Abidjan Convention, Sénégal is preparing a National Plan of Emergency in case ofpollution (POLMAR) but without any effect.

At a national level, the main instrument is the new Environmental Law that was adopted in January2001 (law 2001-01 of the 15 th of January and decree 2001-282 of the 12th of April 2001). A number ofdecrees are ready and, for pollution, will define higher taxes for polluters.

4.3.3.2 Community Responses

The associative movement is quite strong in Sénégal and naturally a lot of local associations (of theyoung like ASCs25, women) have tried to respond to some aspects of the pollution. In 1989, aspontaneous popular movement was born in the suburbs of Dakar, the "Set-Sétal26" movement. Withthis movement a lot of young people and women, either organized or not, decided to voluntary cleantheir neighbourhood by organizing daily popular investments.

In the Hann village, several associations are present like the Sport, Economy and Cultural Associationof Yarakh - perhaps the most active component that began its activities in 1987 -, the youth'sassociation "Takkou Ligguey Walo-Gui" created in 1994, the Groupment of economic interest "Hann

23 Petrosen: Petroleum Society of Sénégal24 SAR: African Society of Refinery25 ASCs: Sports and Culture Associations26 Set-Sétal: operations of cleanliness in Wolof


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Plage Jeunesse Développement" created in 1993, the Hann Fishermen Association (APH) and 13Cultural and Sports Associations (ASC). Since 1987, most of these associations organize humaninvestments to clean the beach and the village but most of the time, each association operates just in itsown action zone and punctually. Also, conferences, workshops and popular theatres have beenorganized to raise public awareness on the danger of pollution. Some associations have participated inthe building of latrines and public lavatories. All these actions were mainly addressing the localdomestic pollution. Their main disadvantage is that they were not coordinated and often limited intime and space. Few actions have been organized to address industrial pollution(IAGU/CUD/CNUEH/PGU, 1997b). But in 1992, a protest movement questioned authorities and thedirector of the incriminated factory and violent demonstrations were organized.

Other actors being present in the Hann bay are:

• The African Institute for Urban Management (IAGU), an international NGO, developed aprogramme for the rehabilitation of the Hann bay. In this way, it is collaborating with themunicipality, through the Urban Community of Dakar (CUD27), and also with the UnitedNations Conference on Human establishments (CNUEH) and the African Bureau for theProgramme of Urban Management (PGU). Since 1993 it has developed a lot of projects for abetter management of the Hann bay as part of the big project "Dakar, a sustainable city" . AnAction Plan for the Integrated Management of the Hann bay and industrial risks alreadyexists (IAGU/CUD/CNUEH/PGU, 1997c). Dispositions relative to the chemical pollution ofthe bay are included in the integrated management of the bay which has two maincomponents, one relative to the Hann zone itself and the second that is relative to the Dakarharbour. The costs of the implantation of a draining system (for domestic sewage) for a totalof 7,500 inhabitants were estimated at 70.3 millions of CFA F in 1997(IAGU/CUD/CNUEH/PGU, 1997d). Monitoring systems as well as institutional framework(structures of coordination, harmonization of legal instruments) are also considered. Duringthe participative exercise organized by the IAGU around the understanding of the pollutionby the population, the suppression of industrial discharges was considered as the first priorityin the context of the integrated management of the bay (IAGU/CUD/CNUEH/PGU, 1997b);

• the UNESCO Club has a cleaning up micro project in collaboration with the ACRA28 NGOand is also working with the APH (Association of the Hann bay Fishermen).

All these actors and initiatives converged and in 1998-1999, an Intersectoral Committee forMonitoring the Hann bay was set up with representatives of the associations, ministries, the Dakarmunicipality, industrials, the Dakar harbour and the civil society (18 people). He is encharged of aportfolio of projects, based on the Action Plan. Recently, one of them ("Participatory Management ofpollution sources in the bay") has been approved for funding by the GEF Small Projects Programmefor an amount of 22.9 million CFA F with co-funding from the Hann municipality (7 million of CFAF) and the industrials (3.5 million CFA F).

The role of the press is interesting since most of the newspapers regularly inform about thedegradation of the Hann bay.

4.3.3.3 Market Responses

Till now, the industries present along the bay prefered to pay taxes instead to solve the problem oftheir sewages. However, with the new Environment Law there is now a general agreement among theindustrials to collectively invest in a treatment plant. Their presence in the Intersectoral Committee isalso a good indice of their new will to adress the problem of industrial pollution.

27 CUD: actually this Community has been dissolved28 ACRA: Association of Rural Cooperation in Africa and South America


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4.3.4 Transboundarity Issues

Of course the case of the Hann bay is quite specific to the Dakar region. However, the same type ofpollution problems is encountered in almost all the big coastal cities in Africa. From this point ofview, it must be considered as an interesting case study.

4.4 Root Causes

They are common to most of the issues and as such are considered separately.

4.4.1 Social Changes

The two main social changes that induce important impacts on the environment are the demographicgrowth and the development of poverty.

4.4.1.1 Demographic Growth and Urbanization

The main social change that exerts pressures on the environment is the demographic growth that isrelatively high in Sénégal (2.7%). This is particularly obvious in the case of chemical pollution whichis illustrated by the Hann bay where high demographic growth in the Dakar region that is linked to ahigh urbanization rate has as first consequence a generation of important quantities of wastes. Forother issues however, the demographic pressure can be exerted either directly (pressures on theresources) or indirectly (search for revenues and exacerbation of sectoral policies). Another problem ispoverty that aggravates the negative aspects of the population pressure.

The urbanization rate increased from 23% in 1960 to 39% in 1988 and 41.2% in 1996. Dakar itselfhouses about the quarter of the total population (2,244,682 inhabitants in 1999, representing 24% ofthe population) (République du Sénégal, 1999).

The density of Dakar increased considerably: 930 people per km2 in 1960; 2,730 in 1988 and 4081 in1999. The growth rate is slightly higher than the mean: 3.7% against 2.7% between 1976 and 1988.

This rapid growth of the capital is attributed to the natural fertility rate that is quite high but also toimportant migratory fluxes that have been exacerbated by the drought. The attraction of Dakar ismainly due to the fact that it is the most equipped town (transport, electricity, water, communications)and also that it presents more job opportunities.

For the environment, the main disadvantage is the growth of wastes. Dakar region is the first producerof wastes: 1,005 tonnes per day and 0.7 kg per day and per inhabitant in 1994 (République duSénégal/Ministère de l’Environnement/Centre de Suivi Ecologique, 2000).

Similarly, the rate of equipment doesn't follow the growth rate and it is particularly true for sewagedrainage infrastructures. In urban areas for example, only 21.1% of the houses use the sewagedrainage network.

4.4.1.2 Poverty

Poverty is recognized as a major problem in Sénégal and a Programme to fight against poverty wasadopted by the Government the 30 th of April 1998. Since then a lot of projects have been implementedin rural and urban areas to reduce poverty, mainly by creating new jobs. More recently a new globalstrategy to reduce poverty is elaborated.

The survey on priorities that was conducted in 1992 indicated that the third of the population livedbelow the poverty level and also that 75% of the poor were in the rural environment (République duSénégal/Ministère de l’économie, des finances et du plan, 1993).


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It is recognized (République du Sénégal/Ministère de l’Environnement, 1997a) that poverty is anaggravating factor for natural resources. Poor people don’t care about environment, they just needfood, water and place to settle. It is considered that by reducing the poverty it will be possible tominimize the impacts on the environment.

4.4.2 Institutional Drivers

The most important root causes at the institutional level are the limits encountered by thedecentralization process as well as a weakness in the application of the laws supposed to protect orcontrol the environment.

4.4.2.1 Limits of the Decentralization Process

Since 1969, with the Third Plan for the National Economic Development (1969-1973), the authoritieshave indicated their willingness to deconcentrate the industries by creating new development poles(Ndiaye, 1995). This orientation has been constantly reaffirmed in the Fourth (1973-1977) and FifthPlans (1977-1981).

In 1996 the law 96-07 of the 22 March 1996 decided the transfer of major responsibilities (inparticular, the protection of the environment) to the decentralized bodies (regions, rural and urbandistricts). This law was considered as a strengthening of the decentralization process.

However, the decentralization process is more theoretical and most of the regions lack the minimuminfrastructures and industries that could allow them to develop. Thus, the inside migration stillcontinue in favour of big urban centres.

Also, most of the municipalities don’t have the human resources to deal with environmental problems.

4.4.2.2 Weakness of Existing Legal Instruments

There is a long list of existing laws that are supposed to contribute to the protection of theenvironment. These laws are International Conventions ratified by Sénégal as well as national lawsand codes (Ly, 1994; République du Sénégal/Ministère de l’Environnement et de la Protection de laNature, 1997a). At a national level, it is important to notice the recent adoption of the newEnvironment Code (law 2001-01 of the 15th of January) (République du Sénégal, 2001). This codeconstitutes the new legal framework for all activities related to the environment.

Moreover, the Senegalese Institute for Normalization (ISN) defined norms for the quality of water, airand soils. However, it was still waiting for application decrees.

However, most of these legal instruments have not been applied for many reasons: inexistence ofdecrees to apply the law (case of the first Environment Code); penalties too low to prevent industriesto discharge untreated sewages in the bay; lack of control and monitoring of the state of the bayrendering impossible the identification of existing or new sources of pollution; corruption of someagents responsible for the control; friendly agreements in most of the case of infractions.

4.4.3 Economic Structure

Two main root causes can be attributed to the economic structure: the first is relative to the differentsectoral policies and the second is the quasi absence of link between the environmental policies andthe sectoral policies.


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4.4.3.1 State of the National Economy

As most of the developing world, Sénégal has an economy characterized by a high level of debtdespite the recent reduction of its debt. In 1999 for example, the current value of the debt was 2.5billion of US $ and the total debt service was estimated to be 237.3 million of US $. Parallelly, theGross Domestic Product was 4.8 billion of US $. The Senegalese economy is under structuraladjustment programmes since the years 80s and was also submitted to a devaluation of 50% of theCFA Franc in 1994. Roughly described it is an economy that is not able to satisfy the basic needs ofmost of the population - that explains the great number of people living below the poverty level - andalso that is obliged to generate revenues - partly to reimburse the debt - mainly by the development ofexportations and the development of the tourism. These last two economic activities exert highpressure on the resources as it was demonstrated when the sectoral policies were described.

4.4.3.2 Sectoral Policies

The organization of the economic development is mainly based on different sectoral policies thatconstitute the national strategic plan. For Sénégal, the last strategic plan was supposed to cover theperiod between 1996 and 2001 (République du Sénégal/Ministère de l’Economie, des Finances et duPlan, 1997) but a new strategic plan is actually elaborated.

These sectoral policies are partly developed to increase the production and it was previously indicatedhow they can induce or aggravate the degradation of the environment and/or resources.

It is also important to note that despite the efforts of the Ministry of Environment, the environmentalpolicies are not really integrated in the development of sectoral policies. It is hoped that theCommission on Sustainable Development and the preparation of the World Summit in 2002 willcontribute to a better integration between these two aspects of the development.


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CHAPTER 5

5. Recommendations

Sénégal was one of the 4 countries that joined the process after the second WGIPA meeting in March2001.

Time was not enough to define concept projects. However, from discussion with the Direction ofEnvironment, it seems that coastal erosion problems as well as pollution of the Hann bay will bepriority projects for them.

A workshop will be convened the second week of December 2001 with all stakeholders to present theresults of this study and request project proposals. From then the national coordinator will forward theproject concepts for Senegal.


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REPORTS

Report of the first meeting of the working group on integrated problem analysis (WGIPA I), 14December 2000, 124 pp.


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Annexes I

Fiche d’identification: Points Chauds, Zones Sensibles et/ou Probleme Primordial

Point Chaud 1

1. Titre: Hann Bay.

2. Region (administrative) et localisation: Cap Vert, southern part.

3. Superficie/Definition:

5. Elements de regionalisation (notez dans quelle mesure le site a des repercutions sur d’autrespays ou region, et, de meme, dans quelle mesure des sites proches ont une influence sur lesite en question): None.

6. Problematique (GIWA Issue(s)): 6, 5, 4, 7, 8.

7. Contexte du site:

7a. Activites humaines principales sur le site:

Fisheries and industries.

7b. Conditions et phenomenes naturels en relation avec le site:

Bay with a very restrited circulation.

8. Characteristiques et etendue de la menace de degradation (causes humaines ou naturelles):

This site is highly degraded, eutrophication being the more obvious manifestation of thispollution. This has consequences on fish communities.

9. En cas de presence significative de pollution, listez les origines (point, non point, diffuse) etprecisez les sources:

The main sources of pollution are the canal VI (polluted waters non treated), the main industriesrejecting their wastes directly in the sea.

10. Valeur du site: Local National Regional/globalImportanceenvironnementale

Very high Very high None

Importance Socio-economique

Very high High


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Point chaud 2

1. Titre: Djoudj National Park.

2. Region (administrative) et localisation: Saint-Louis, northern part of the country.

3. Superficie/Definition: 160 km2 , Ramsar site, Site of the World Heritage.

5. Elements de regionalisation (notez dans quelle mesure le site a des repercutions sur d’autrespays ou region, et, de meme, dans quelle mesure des sites proches ont une influence sur lesite en question):

Ramsar site, Site of the World Heritage, one of the main West Africa sanctuaries for palearcticbirds. Linked with the

6. Problematique (GIWA issue(s)): 1, 13, 5.



Agriculture, Fisheries and Tourism.

7b. ................................................. Conditions et phenomenes naturels en relation avec le site:

......................................................................................................................................Wetland.

8. Caracteristiques et etendue de la menace de degradation (causes humaines ou naturelles):

This site is invaded by a new plant, Salvinia, which is now occupying numerous parts of the watersurfaces, impeding fishing activities but also threatening birds that are no longer able to feed.


10. Valeur du site: Local National Regional/globalImportanceenvironnementale

Very high Very high Very high


Very high High Limited


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Point chaud 3

1. Titre: Djiffere.

2. Region (administrative) et localisation: Fatick, about 200 km south of Dakar.

3. Superficie/Definition: km2.


6. Problematique (GIWA issue(s)): 13, 8.







10. Valeur du site: Local National Regional/globalImportanceenvironnementaleImportance Socio-economique


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Sensitive area 1

1. Titre: Casamance estuary.

2. Region (administrative) et localisation: Ziguinchor, about 250 km south of Dakar.

3. Superficie/Definition: km2.











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Sensitive area2

1. Titre: Senegal Delta.

2. Region (administrative) et localisation: Saint-Louis, about 200 km north of Dakar.

3. Superficie/Definition: 1500 km2.











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Sensitive area 3

1. Titre: Saloum estuary.

2. Region (administrative) et localisation: Fatick, about 200 km south of Dakar.

3. Superficie/Definition: 4309 km2.









10. Valeur du site: Local National Regional/global

Importance environnementale
