近廿年来官厅水库流域水土保持拦沙量估算

自1983年官厅水库永定河上游流域被列为国家重点水土流失治理区以来，在近廿年的时间内，流域内进行了大量的水土流失治理工作，据调查截止2000年年底，山西省大同地区治理水土流失面积4205．8km^2，河北省张家口地区治理水土流失面积6449．11km^2，北京市延庆县妫水河流域治理水土流失面积435．33km^2，三省市共治理流失面积ll090．24km^2，其中治理面积保存率在90％以上。对不同治理措施拦沙量的估算结果表明各类水土保持措施拦沙总量为3．51亿t，水土保持拦沙量占流域总产沙量的20．53％，水土保持措施拦沙对减少官厅水库泥沙的淤积起到了积极的作用。

Estimation of sediment reduction by water and soil conservation of Guantingreservoir watershed in recent twenty years

The Guanting reservoir watershed, a very serious erosion watershed with an erosion area of 43402km 2, is located in the upper reach of Yongdinghe River. Since the soil and water conservation was implemented in 1983, an area of 4205.8km 2 in the Datong region, Shanxi Province, have been controlled by soil and water conservation, 6449.11km 2 in the Zhangjiakou region, Hebei Province, and 435.33km 2 in Yanqing county, Beijing. That is to say a total area of 119090.24km 2 has been treated with soil and water conservation, and so far 90% of them are still in function. The estimated results show that 0.351 billion tons of sediment has been reduced by soil and water conservation, which accounts for 20.53% of the total sediment yield in the watershed. Soil and water conservation has been playing an important role in reducting sedimentation of the Guanting reservoir.