The Contribution of Horizontal Subsurface Drainage to Solving the Aral Sea Economic and Environmental Problem

There are 7.6 million hectares of irrigation development along the rivers Syr Darya and Amu Darya in Central Asia. Approximately one-half of this was developed since 1960. As a result, the volume of water reaching the land-locked Aral Sea has reduced dramatically, so that in only 30 years the level of the Aral Sea has fallen by 15 metres, the volume has decreased by 70%, and the salinity has increased so much that the once-productive fishery is now dead. The level of the Sea continues to drop at a rate of 0.3 m per year. Irrigation is estimated to consume 98 km3 of water per year (Bos 1995) or an average application rate of 1.24 m. Subsurface drainage has been installed in a large portion of the Aral Sea irrigation area but with widely spaced tubes, generally 800 m apart, installed at depths of 2.5 to 3.5 m.