IMPACT OF AGRICULTURAL WATER ALLOCATION ON THE ECOSYSTEMS IN THE INNER NIGER RIVER DELTA

Abstract

The Niger River is a lifeline for humans and biodiversity in Africa’s Sahelian region. Owing to
climate change and population increase over the past three decades, the inhabitants of the Sahel have witnessed
that their ecosystem is under threat, and a significant reduction of its resources has occurred, particularly in the
Inner Niger Delta. In the recent years, because of the Malian government’s policy of developing large-scale
irrigation, a sustained rate of expansion of around 5,000 ha of new reclamation area has been seen each year in
Office du Niger located upstream of the Inner Delta. The expansion of annual rice double cropping and
sugarcane cultivation constitute the main factors for the reduction of the water resources downstream in this
Delta. This paper analyzes the hydrological impacts of this large-scale irrigation and crop pattern on the
floodplain of the Inner Delta during high-flow and low-flow periods. The study results indicated that despite
the rainfall and recent increases in upstream flows of the Niger River, the flooded area size has reduced. We
could confirm that the annual average water-withdrawal proportion barely changed during the high-flow period
but changed significantly during the low-flow period when the size of the paddy rice and sugarcane area
increased. Therefore, changing the crop pattern toward vegetables instead of paddy rice and sugarcane during
the low-flow period might be a solution.