Lake Chad is drying up.
The size of Lake Chad has increased and shrunk at regular intervals. Increasing aridity in the Sahel area and more demand for freshwater for irrigation may however entail that Lake Chad will continue shrinking. Lake Chad varies in extent between the rainy and dry seasons, from 50,000 to 20,000 km2. Precise boundaries have been established between Chad, Nigeria, Cameroon, and Niger. Sectors of the boundaries that are located in the rivers that drain into Lake Chad have never been determined, and several complications are caused by flooding and the appearance or submergence of islands. A similar process on the Kovango River between Botswana and Namibia led to a military confrontation between the two states.
Climate change exacerbates the drying up of already arid zones in Africa. Vorosmarty and Moore (1991) have documented the potential impacts of impoundment, land-use change, and climatic change on the Zambezi and found that they can be substantial. Cambula (1999) has shown a decrease in surface and subsurface runoff of five streams in Mozambique, including the Zambezi, under various climate change scenarios. For the Zambezi basin, simulated runoff under climate change is projected to decrease by about 40% or more.Growing water scarcity, increasing population, degradation of shared freshwater ecosystems, and competing demands for shrinking natural resources distributed over such a huge area involving so many countries have the potential for creating bilateral and multilateral conflicts (Gleick, 1992).