Welcome to AGRHYMET. Dr Abdou ALI, Hydroclimatologist PB 11011, AGRHYMET, Niamey, Niger

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1 Welcome to AGRHYMET Dr Abdou ALI, Hydroclimatologist PB 11011, AGRHYMET, Niamey, Niger Expert Meeting on Hydrological drought indices Geneva, Switzerland, 1-2 September, 2011

2 Outline AGRHYMET Regional Water Resource monitoring in West-Africa Relationship Meteorological/ hydrological droughts in West-Africa: some paradoxes? Conclusion 2

3 AGRHYMET creation and Area of intervention AGRHYMET = AGRrometeorology, HYdrology, METeorology AGRHYMET was created in 1974, following the catastrophic droughts of the early 1970 s, at its creation, 9 member states: Burkina, Cape Verde, Chad, The Gambia, Guinea- Bissau, Mali, Mauritania, Niger, Senegal. AGRHYMET as a technical arm for the Economic Community Of West African States (ECOWAS), extends its activities to cover the whole CILSS/ECOWAS countries

4 The AGRHYMET Regional Centre s mandate To collect and process data and disseminate information on: food security, water resource management desertification control and climate change impacts; To build technical capacities through training and transfer of tools, methods adapted to the Sahelian countries in climatology, Agrometeorology hydrology information technology crop protection, Geomatics To strengthen interstate co-operation by sharing methodologies and technologies between member states

5 The AGRHYMET Regional Centre Control and Evaluation Bodies The head of the member States Summit (each 2 years) The minister of the member states council (twice a year) Technical and Management Committee (CTP) CAMES (African and Malagasy Council for Higher Education) An international Scientific and Academic Advisory Board (composed of 8 well renowned scientists from West Africa, Europe, USA and Canada) WMO certified training center AGRHYMET is represented in each country by a national Multidisciplinary working group AGRHYMET is 71- hectare estate, six laboratories, two main departments (research and information department and training and research department)

6 Regional Water Resource Monitoring

7 High sensitivity of the Sahelian region activities to the rainfall variability Less than 5% of surface water resources are controlled Only one rainy season per year from June to October (but more 85% of the total rainfall falls between in July, August and September) More than 90% of Sahelian agriculture are rainfed

8 STATIONS HYDROMETRIQUES Transboundary River PRESAO II basins in West-Africa # # Cours d'eau Limite Cours d'eau Limite des Pays Bassins Chari Comoé Gambia Gorubal Komadugu Niger Sénégal Volta # BaKel Niamey Gouloumbou Douna (Bani # # # Kedougou Garbe-Kouro # # Dioila (Bao # Mallanville Simenti Dialakoro # ## # Pankourou ( # Faranah Kouroussa # Beterou # Bui Baro # # Seme Bambou # Lokoyo Makourdi # # Bonou # # Ati # N'Djamena Lai # Moundou Surface water concentrated within few river basins: a specificity of West-African hydrological system # # # Sarh

9 Water Dependence Index, UNWWDR2, AQUASAT, FAO, Benin Burkina 0 Cape Verde Cote d'ivoire Gambia Ghana Guinea Guinea-bissau Liberia Mali Mauritania Niger Nigeria Senegal Serra Leone Togo

10 River discharge measurement stations and use of satellite data Around 250 hydrometric stations

11 Monitoring from hydrometric stations: river discharge and dam reservoir water levels Fig. 3: COMPARATIVE HYDROGRAPH OF RIVER NIGER AT DIRE/ Hydrogrammes Compares du Fleuve Niger à Diré (MALI) 2500 Fig. 4: COMPARATIVE HYDROGRAPHS OF RIVER NIGER IN NIAMEY/ HYDROGRAMMES COMPARES ANNUEL DU FLEUVE NIGER A NIAMEY (NIGER) Discharges/Debits (m3/s) Discharges/Debits (m3/s) juin 15-juin 29-juin 13-juil. 27-juil. 10-août 24-août Quiquennale sèche Moyenne Q_2nal humide Q_2009 Q_ juin 16-juin 1-juil. 16-juil. 31-juil. 15-août 30-août Quiquennale sèche Moyenne Quiquennale humide Q 2009 Q Fig. 6: SITUATION OF SELINGUE DAM RESERVOIR WATER LEVEL / SITUATION ANNUEL DU NIVEAU D'EAU DU BARRAGE DE SELINGUE (MALI) 346 Water level/niveau d'eau (cm) juin 16-juin 1-juil. 16-juil. 31-juil. 15-août 30-août / / / /11

12 Water Resources monitoring, use of satellite data 23/01/ /01/ /01/1997 Evolution of Lake Chad surface water

13 Water Resources monitoring, use of satellite Densité en eaux de surface par régions administratives Monitoring of the number of small water bodies (ponds density)

14 Hydrological seasonal Outlook for West-Africa average streamflow the rainy season

15 Dissemination of the Information The AGRHYMET monthly bulletin The Decision makers special bulletin Radio Public conferences Web site

16 Meteorological drought in the West-African Sahelian Region

17 Drought in the Sahel Severe drought by its spatial extent WMO Inter-Regional Workshop on Indices and Early Warning Systems for Drought Lincoln, Nebraska, USA, 8-11 December

18 Severe drought started in 1970, by the magnitude and persistence of dry years Persistence of dry years Persistence of wet years Equateur Abrupt change from very wet to very dry years Another mode of inter-annual variability seems to be established in the Sahel

19 Different period Isohyets : bands : red : blue

20 Meteorological Drought impact on hydrology in West-Africa: too little water

21 Streamflows of main rivers in WA

22 Changes compared water availability(40-60%) Niger at Malanville: km²

23 For example, direct impact of the Monsoon rainfall on Niger River discharge Rainfall in the Niger River bassin at Koulikoro in Mali Discharge of the Niger River at Koulikoro in Mali

24 Mean hydrograph: comparison between the wet and dry periods avant 1969 après 1969 Discharge (m 3 s -1 ) juin 18-août 07-oct 26-nov 15-janv 05-mars 24-avr 13-juin Date

25 In 1985, for the first time, in living memory, the Niger River stopped flowing

26 Lake Chad shrinking

27 Decrease of aquifer water table

28 Meteorological Drought / hydrological situation West- Africa: Too much water

29 Increase of discharge

30 Intra-seasonal trend in hydrology

31 Increase of aquifer water table level Niamey region Increase in the groundwater depth (Niger), Leduc et al., 2001

32 Fluctuation of groundwater level depth (Burkina Faso) From DGIRH, Burkina,

33 Evolution of the surface area of lake Chad

34 Too little water decrease of water availability(40-60%) great reduction of wetland areas Decrease of groundwater table Too much water Increase of the discharge for small and localized systems Increase of runoff coefficient and discharge, due to great modification of land use land cover Increase of aquifer water table, due to land use land cover changes and recharge process

35 Some parameters which play an important rule in West-Africa The length of the flow duration is important The number of ponds The runoff coefficient Accumulation of sand in some areas play important rule in aquifer recharge

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