Groundwater resources in the ECOWAS region -Expected aquifer productivity map

International audience ; Groundwater plays an important role in supporting agricultural and domestic water supply in West Africa, with more than 50 % of the population currently dependent on groundwater for their main drinking water source. It could play an increasingly important role in adapting to climate change in West Africa, which is projected to cause "increases in drying and agricultural and ecological droughts as well as delayed onset and retreat of the monsoon season"[1]. Consequently, hydrogeological information is essential for the Economic Community of West African States (ECOWAS) member states to undertake effective groundwater management and support the strategic, sustainable development of new groundwater resources, with consequent lasting socioeconomic benefits across West Africa. This map Groundwater resources in the ECOWAS region [2] capture and standardise existing groundwater data and understanding developed in the ECOWAS countries. The expected aquifer productivity map updates older regional hydrogeological maps of West Africa, to give a consistent regional overview not available from individual national maps. It provides a quantitative assessment of aquifer productivity, as a measure of groundwater potential, highlighting the suitability of aquifers for water supply at different scales and the physical limits of groundwater development potential. Building on readily available data, the expected aquifer productivity map and the accompanying inset maps show the potential for assimilating and harmonising existing hydrogeological information to improve regional groundwater mapping across Africa.