Recent changes in Lake Chad: Observations, simulations and management options (1973-2011)

Abstract The spectacular drying of Lake Chad around 1970 has been widely reported in the media. The lake is now divided into different individual seasonal or perennial lake pools. Paradoxically, our understanding of the hydrology of the lake in its present state remains poor. In particular there is a lack of fundamental hydrological data to quantify the drought and limited information about water management options. The hydrologic changes are the driving forces for the natural resources associated with the lake i.e. fisheries, recession cultivation on the lake floor and green vegetation for livestock. Whereas the yearly cycle of the natural resources has become fairly predictable in the southern pool of the lake, variability and vulnerability have increased greatly in the northern pool. Here we use a hydrological model of Lake Chad developed recently to i) reconstruct the past levels and inundated areas in order to compensate for the lack of hydrological data and, ii) simulate the effects on the lake of modifications in the entering fluxes, either by abstraction for irrigation purposes, addition from an inter basin transfer or impact of climate change. The study period runs from 1973 to 2011 with a total inundated area of the lake ranging between 1800 and 15,000 km 2 .