The Inter-Relationship Between Irrigation, Drainage and the Environment in the Aral Sea Basin

The irrigated area in the Aral Sea basin totals about 7.5 million ha. Part of the water supplied to this area is consumed by the irrigated crops; the remainder drains into the groundwater basin, downstream depressions, or back into the rivers. But the water accumulates salts and chemicals during its period of use, causing environmental problems which this book discusses. The natural discharge capacity of the groundwater basin is inadequate to handle the unconsumed irrigation water, leading to a rise in the groundwater table and to waterlogging. In (semi-) arid zones, this waterlogging triggers a soil salinity problem, resulting in poorer crop yields. The problem is solved by artificially increasing the discharge capacity and lowering the groundwater table. Since the lands surrounding the Aral Sea have become independent republics, a number of missions have reported on the water-related environmental problems in the basin. Such reports have contributed to a plan of action for solving or alleviating some of the problems identified, high priority being accorded to improving the irrigation efficiency, artificial drainage, and the related environmental effects.