Constraints of future freshwater resources in the Upper Niger Basin – Has the human-environmental system of the Inner Niger Delta a chance to survive?

The Inner Niger Delta in the West African Sahel is one of the largest wetlands in the world. Growing populations and developing living standards in the Upper Niger Basin are increasing the needs for food and energy and put enormous pressure on limited natural resources. The extension of irrigated agricultural areas and the construction of new dams and reservoirs to store and distribute water and to generate hydropower seem to be necessary strategies to satisfy the increasing demands. As a consequence, the natural water regime of the River Niger is modified and will be subject to further regulation with largely negative effects for the Inner Niger Delta in Mali. Climate projections, used in this study, in combination with reservoir control lead to a significant reduction of peak discharges and are thus a large threat for the wetland’s ecosystem functions. Hydropower generation requires water during the dry season and consequently, the low flows are considerably increased due to dam management. The latter has certainly positive effects on water quality and thus on human health, but might also have negative impacts on the IND ecosystem that is accustomed to or even requires extremely dry and wet conditions to maintain its integrity. The impacts of climate change and reservoir control strategies on wetland inflows and inundation patterns as well as mitigation options are investigated in this study by analysing various water management and regionalised climate scenarios. The usage of “excess” water due to increased discharges in the dry season for irrigation could be such a mitigation strategy. A process-based eco-hydrological modelling system equipped with an inundation module and a reservoir module was used for this purpose.