A government official explains the South Chad Irrigation Project. The ambitious scheme, which began in the 1970s, was designed to irrigate tens of thousands of hectares of arable land. But even before construction had begun the lake had started to recede. Hundreds of miles of canals were built, but the canals were not lined and the water simply drained away into the desert. Only a third of the land was ever irrigated. The southern part of the lake dried up, and now the canals and the land are barren. Lake Chad is drying up, due largely to desertification as the Sahara advances southward. This advance is caused in part by global warming which has reduced rainfall in the region, weakening plants whose roots once held topsoil in place. The lake is also drying up because water is pumped out from the lake by government sponsored irrigation schemes.