Environmental effects induced by human activities in arid Shiyang River basin, Gansu province, northwest China.

Shiyang River basin is located in Hexi Corridor, central-west Gansu province, northwest China. It is an area of typical arid to semiarid features. During the last century, especially the last half century, mankind's production activities have caused a series of detrimental environmental effects, which are summarized: water environment change, land desertification and salinization, and vegetation degeneracy. Changes in the water environment include the surface water system, water quantities, continuous lowering of the groundwater table and degradation of groundwater quality. Vegetation cover in the lower reaches is seriously degenerated, resulting in land desertification, salinization and dust storms. Analysis indicates that the rate of the groundwater table lowering in Shiyang River basin generally exceeds 0.3 m/year, and the mean annual rate of groundwater decrease in Wuwei and Minqing sub-basins reaches 1.11–3.98%. Until 1998, the shortage of groundwater volume was 4.526×10⁸ m³. If no effective measures are taken, this figure will be 6.728×10⁸ m³ in 2010. Remedial actions include: (1) recovery and protection of the water conservancy function of the mountain forests to ensure the sustainable development of this recharge area; (2) establishment of an authoritative agency to reasonably allocate the total water resources in Shiyang River basin; and (3) enactment of legislation and economic control to build up a water-saving society in Shiyang River basin. [ABSTRACT FROM AUTHOR]