1. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20021 V&A Studies on coastal zones: the case of Senegal Dr Isabelle NIANG-DIOP Department of Geology, Faculty of Science and Technology University Cheikh Anta Diop, Dakar (SENEGAL) isabelle@enda.sn

2. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20022 The Senegal example Two studies realized (1991 and 1999) Conditions Results (for a sea level rise of 1 m by 2100) What to deduce ?

3. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20023 Conditions First study Study in collaboration with USA All the Senegalese coastline EPA funding (17,391 – 26,087 US$ ) 10 months (may 90 – february 91) Video recording (AVVA) Second study Pluridisciplinary team (11 experts) Case studies : Cap Vert and Saloum Netherlands funding (86,000 US$ ) 2 years (97-99) Remote sensing and GIS

4. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20024 Methodologies used The Common Methodology (IPCC, 1991), basis for the IPCC methodology (Carter et al., 1994). The seven steps methodology Based on scenarios Climate change scenarios Sea level rise scenarios (used in the 2 studies) Inundation levels Other climate parameters (temperature, precipitations,..) Socio-economic scenarios Population growth Economic growth

5. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20025 Sea level rise scenarios S r, t = S g, t + S o, t + V. t avec S r, t : relative sea level rise in t years S g, t : global mean sea level rise in t S o, t : regional changes in sea level due to oceanic circulation (currents, …) V : earth movements (m/year) t : number of years considered

6. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20026 Sea level rise with the SRES See IPCC Third Assessment Report (2001)

7. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20027 Inundation levels (Hoozemans et al., 1993) D = MHW + S f + W f + P f MHWmean high water level S f sea level rise W f heigth of storm waves of a given return period P f rise in sea level due to barometric pressure

8. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20028 Socio-economic scenario the discount rate Controversial question (utilitity, rate) Multiplicator factor D t = 1 / (1 + r) t D t is discount factor in year t and r the discount rate used (2 to 7%)

9. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 20029 Scenarios generation Climate change scenarios See the training workshop CC scenarios generators (MAGICC-SCENGEN, regional CC models) Downscaling, national CC scenarios Socio-economic scenarios National scenarios (to be preferred) United Nations and others scenarios (WB, UNDP, WRI,…)

10. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200210 Scenarios used First study Climate change scenario Sea level rise by year 2100 : 0.2; 0.5; 1 and 2 m Inundation levels 2m 1m 0.5m No socio economic scenario

11. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200211 Scenarios used Second study Climate change scenario Sea level rise 2050 : 7, 20, 39 cm 2100 : 20, 49, 86 cm Inundation levels The minimum inundation level by 2100 is calculated for minima values of the mean high sea level, mean swell heights and the low estimation of sea level rise. The maximum inundation level considers mean values of the mean high sea level, storm waves with a 1/100 return period and the high estimation of sea level rise. Coast north of Dakar : 2 and 8 m Coast south of Dakar and Saloum : 2 and 6m Other parameters Temperature rise : 1° and 1.9°C by 2050 Precipitation decrease : -1 to –10% in Cape Verde ; -1 to –15% in Saloum

12. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200212 Scenarios used Second study Socio-economic scenario Population growth Cap Vert : 2.99% Saloum : 2% Agricultural production growth rate O.41% Discount rates 3 and 6%

13. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200213 Impacts assessment Biophysical impacts Land losses due to Coastal erosion Inundation Salt water intrusion in coastal aquifers Coastal ecosystems Halieutic resources and fisheries

14. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200214 Impacts assessment Socio-economic impacts Population at risk Economic value at risk Buildings Infrastructures Agricultural production

15. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200215 Coastal erosion induced by SLR The Bruun rule (1962) A simple rule but based on a number of assumptions (equilibrium profile) R = G L s (B + d) R is the coastal retreat, L the width of the active profile, B the dune heigth, d the depth of closure, s the sea level rise and G a overfill ratio

16. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200216 The Bruun rule (1962) B s d L R Profile translation

17. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200217 Coastal inundation In the second study Inundation levels considered as contour levels. Digitalization of contour levels Satellite images transformed and land-use maps Use of a GIS : combination of the two types of information Generation of areas and types of inundated coastal zones

18. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200218 Other biophysical impacts (1) Salt water intrusion in the coastal aquifers the Ghyben-Herzberg formula : determine the depth and distance to the coast of the interface sea water / freshwater (see UNEP guidelines) the FEFLOW model was calibrated and used to determine the evolution of the salt water intrusion in the Dakar aquifer (Faye et al., 2001) Coastal ecosystems (expert judgement) « niayes » ecosystem : based on the comparison with historical data Mangroves : analogue study

19. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200219 Other biophysical impacts (2) Halieutic resources (expert judgement) Marine resources Diminution in the intensity of upwellings and surface waters warming Modification in coastal habitats (mangroves) Estuarine resources Increase of salinity Increase of the dynamics Disparition of mangroves

20. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200220 Socio-economic impacts First study Based on the video recording and analysis of buildings Types of buildings with value attribution  economic value at risk Rate of occupancy : 1O people in 100 m 2  population at risk

21. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200221 Socio-economic impacts Second study Based on the analysis of inundated areas Population density by zones and growth rate  population at risk Density of inhabitants by house (7.5 in Dakar and 9.6 in the Saloum estuary)  habitat at risk Capital and added value by hectare  Industrial value at risk (only for the Mbao industrial zones) Road lengths and types identified, value per km and type applied  road infrastructures at risk area of agricultural production multiplied by yields and a growth rate  agricultural production at risk

22. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200222 Adaptation assessment First study Two options considered: Protection of important areas Total protection (coasts with  10 inhabitant per km 2 ) Two types of protection options Seawalls : unit costs For a 0.5 m SLR : 0.12 to 2 million US$ per km For a 1 m SLR : 0.33 to 2.30 million US$ per km Beach nourishment : unit costs : 6 US$ per m 3 plus costs of terminal groins

23. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200223 Adaptation assessment Second study Protection option Coastal protection works (seawalls and groins) Seawalls: 2.2 to 4.6 million US$ per km Dune fixation : unit costs per ha Other types of measures

24. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200224 Vulnerability assessment vulnerability classes (Nicholls, 1995) Categories of impactsVulnerability classes LowMiddleHighCritical Populations at risk (in % of total population) Economic value at risk (in % of GDP) Land losses (in % of total area) Loss of wetlands (in % of total area) Costs of protection/adaptation (in % of GDP) < 1% < 1% < 3% < 3% < 0,05% 1 – 10% 1 – 3% 3 – 10% 3 – 10% 0,05– 0,25% 10 – 50% 3 – 10% 10 – 30% 10 – 30% 0,25 - 1% > 50% > 10% > 30% > 30% > 1%

25. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200225 Results of the first study (for a 1 m SLR) Land losses - Inundation - Erosion 5,987 km 2 55 – 86 km 2 Population at risk112 000 –183 000 1.4 – 2.3 % 1990 population Economic value at risk499 – 707 millions US$ 12 – 17 % PNB 1990 Protection costs (important zones) 255 – 845 millions US$

26. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200226 Results of the second study (for a 1 m SLR) Cap Vert (1597 km 2 ) Saloum (4309 km 2 ) Land losses - Inundation - Erosion 57 – 398 km 2 2.9 – 4 km 2 1,690 – 2,911 km 2 0.8 – 4 km 2 Population at risk (in 2100) 730,249 - 4,787,828 847,191 to 11,807,410 Economic value at risk (with a 3% DR) 4.4 – 29.7 milliards $4 – 55.3 milliards $ Protection costs (with a 3% DR) 0,004 – 0,026 M$0.06 M$

27. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200227 Mangrove estuaries

28. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200228 Comparison of the 2 studies (for a 1 m sea level rise) 1st study : Sénégal 2nd study: Saloum Land losses by: Inundation Coastal erosion 5,987 km 2 55 – 86 km 2 1,690 – 2,911 km 2 0.8 – 4 km 2 Population at risk112,000 –183, 000847,191 - 11,807,410 Economic value at risk 0.5 – 0.7 milliard US$ 4 – 55.3 milliards $ Protection costs0.3 – 0.8 milliards$0.06 milliard$

29. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200229 Results of the second study 1. Other impacts Lowering of piezometric levels and salinization of numerous coastal aquifers Risks of disparition of the guinean vegetation typical together with apparition of halophyte species in the « niayes » and modifications of mangrove. The risks are less till a 0.5 m SLR Diminution of the halieutic production and of landings. Changes in the species composition. Health problems, conflicts, employment

30. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200230 Results of the second study 2. Other adaptation options Need for ICZM Better management of coastal and marine resources (water, halieutic and estuarine resources, ecosystems) New institutional, legislative measures Promotion of technical measures (recuperation of salted soils, creation of a CC research center) No quantification of these measures

31. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200231 The example of Sénégal : conclusions Don’t expect to have more than you invest Big differences in the results depending on the methods used specially for population and economic value at risk Confirmation of the high vulnerability of the country (south coast and estuaries in particular) Importance of monitoring, sustainable management of resources, … But how to take these issues in the development agenda of the country?

32. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200232 The example of Sénégal : conclusions It is not finished! New scenarios, models are coming Still limitations in the studies : biophysical impacts to be quantified, economic valuation of mangroves, consideration of other sectors And how to take these adaptation options in the development agenda of the country?

33. 3 june 2002 AIACC V&A Training Workshop, Trieste, 3-14 june 200233 THANK YOU !