Sub-Saharan African G-WADI

Sub-Saharan African G-WADI Regional chapter of the Global network on Water and Development Information for Arid Lands Prof. Cheikh B. Gaye

G-WADI Workshop 20-21 April 2010 Dakar, Senegal 35 participants from 12 countries

G-WADI/Africa: Strategy Build on the existing expertise and know how (involvement of three sub-regional centres (AGRHYMET, ICPAC, SADC-DMC) Stakeholder mapping needs to identify key stakeholders and their intervention areas within arid and semi-arid zones in SSA Work in synergy with the other UNESCO-IHP networks in SSA such as FRIEND, ISARM, GRAPHIC and the network of HELP basins.

G-WADI/Africa: Expectations Agreement by African delegates to the formation of a G- WADI network for the SSA region which compliments those on other continents. Support for this from International partners. To explore the scope of regional scientific projects relating to arid and semi-arid regions of SS Africa and the impacts they have had or are having on development and policy. To determine the research inputs and requirements of policymakers in dealing with water security in water scarce areas of SS Africa

G-WADI/Africa: Expectations How to make scientific data and knowledge about this region more accessible and see how scientific solutions could be better taken up or promoted. Identify existing gaps and needs in capacity development related to research, curricula development and also institutional capacity relating to water resources (sensu lato) in relation to arid and semi arid regions of SS Africa.

G-WADI/Africa: Expectations Promoting improved scientific exchange relating to water management and for developing a G-WADI network in arid and semi-arid areas of SS Africa To strengthen the ties between French and English partners in SS Africa through the formation of the G- WADI network. Promoting improved scientific exchange relating to water management and for developing a G-WADI network in arid and semi-arid areas of SSA

G-WADI/Africa: Network structure A secretariat to be hosted by an institution (sub-regional institution) A steering committee composed with representatives of key African centres and individual experts Key themes each one led by an expert or institution

G-WADI/Africa: Potential themes Water augmentation techniques including rain water harvesting and aquifer recharge Soil-water management techniques Monitoring tools including early warning and drought monitor Experimental basins and modeling Data, particularly rainfall data

G-WADI/Africa: Follow up activities Mapping of stakeholders with their profile regarding activities related to arid and semi-arid areas. The organizational structure of the network including TORs and suggestion on the members (hosting institution for the secretariat, members for the steering committee, proposition of themes and leading agency for each theme,..)

Architecture of a website to be hosted by the subregional institution hosting the secretariat of the network (or at UNESCO s HQ or regional office) Detailed activities for the network for the next two years. Strategy for fund raising for the implementation of some of the identified activities.

G-WADI/Africa: Suggested Plans for future A G-WADI activity on Science to Policy will be set up, led from Africa and extended to other regions

Formal creation of G-WADI Sub Saharan Africa After extensive discussions on the relevance of the G-WADI network in Sub- Saharan Africa, the participants agreed to formally establish a G-WADI network in Sub-Saharan Africa. Paris - 9th December 2010

Transfer of Princeton University Drought monitoring to Africa Workshop in Niamey (Niger) Feb 2011 Workshop in Nairobi (Kenya) June 2011 Contribution to the special issue of SCAR journal (2013) Workshop on satellite and ground-based data merging Niamey (July 2013) Workshop on Drought monitor Niamey 2013

Opening ceremony of the G-WADI drought monitoring workshop in Niamey, Niger AFRICAN DROUGHT MONITOR

Training: practical sessions

The drought monitoring web site

Evaluation des performances du modèle hydrologique VIC Ce rapport fait suit à l atelier qui s est tenu à Niamey (Niger) du 30 janvier au 03 février 2012. Centre Régional AGRHYMET du transfert d un outil hydrologique sur le suivi de la sécheresse développé par l Université de Princeton

Pluies journalières estimées par satellites et observées (période 1970-1980) 160 140 120 100 80 60 40 20 0 01/01/1970 01/01/1971 01/01/1972 01/01/1973 01/01/1974 01/01/1975 01/01/1976 01/01/1977 01/01/1978 01/01/1979 01/01/1980 Pluie_VIC Pluie_Obs

Pluies journalières estimées par satellites et observées (en 1970) 120 100 80 60 40 20 0 01/01/1984 01/02/1984 01/03/1984 01/04/1984 01/05/1984 01/06/1984 01/07/1984 01/08/1984 01/09/1984 01/10/1984 01/11/1984 01/12/1984 Pluie_VIC Pluie_Obs

Pluies journalières estimées par satellites et observées (en 1984) 100 80 60 40 20 0 15/04/1970 29/04/1970 13/05/1970 27/05/1970 10/06/1970 24/06/1970 08/07/1970 22/07/1970 05/08/1970 19/08/1970 02/09/1970 16/09/1970 30/09/1970 14/10/1970 28/10/1970 11/11/1970 25/11/1970 Pluie_VIC Pluie_Obs

Débits mensuels observés et calculés 900 800 700 Debits (m3/s) 600 500 400 300 200 100 0 mai-70 mai-72 mai-74 mai-76 mai-78 mai-80 mai-82 mai-84 mai-86 mai-88 mai-90 mai-92 mai-94 mai-96 mai-98 mai-00 mai-02 mai-04 mai-06 mai-08 Obs Modele_VIC

en année humide (1994) et en année sèche (1984) Debits (m3/s) 250 200 150 100 50 0 janv-84 mars-84 mai-84 juil-84 sept-84 nov-84 Debits (m3/s) 800 700 600 500 400 300 200 100 0 janv-94 mars-94 mai-94 Obs juil-94 sept-94 nov-94 Modele_VIC Obs Modele_VIC

Corrélation entre débits mensuels calculés et observés 900 Modele_VIC (m3/s) 800 700 600 500 400 300 200 100 0 y = 0.8671x + 19.815 R 2 = 0.8147 0 100 200 300 400 500 600 700 800 900 Obs (m3/s)

Débits observés et calculés en année humide (1970-71) et en année sèche (1983-84) Debits (m3/s) 1200 1000 800 600 400 200 0 01/05/70 01/07/70 01/09/70 01/11/70 01/01/71 01/03/71 01/05/71 01/07/71 01/09/71 01/11/71 Debits (m3/s) 1200 1000 800 600 400 200 0 01/01/83 01/03/83 01/05/83 01/07/83 01/09/83 01/11/83 01/01/84 01/03/84 01/05/84 01/07/84 01/09/84 01/11/84 Obs Modele_VIC Obs Modele_VIC

CONCLUSION Au vu des résultats obtenus on peut tirer les conclusions suivantes : Les estimations de pluie par satellite sont acceptables et peuvent constituées une alternative en cas de lacune de données observées ; Le modèle VIC est assez robuste pour la simulation des écoulements ; le modèle reproduit d une manière satisfaisante la forme des hydrogrammes observés. Les débits de pointes calculés sont bien situés dans le temps mais parfois sous-estimés ou surestimés; Donc, on doit fortement encourager le processus de transfert de l outil au CRA mais aussi voir comment le faire tourner avec les données observées.