白鱼河流域生态效济型水土保持综合治理成效分析

陕西省白鱼河流域是典型的秦巴山地变质岩水土流失区，长期以来。水土流失严重，生态环境恶劣，平均年侵蚀模数４５００ｔ／ｋｍ２以上，森林覆盖率仅１４．８％，水土流失制约着流域内生产活动和经济发展。１９８２年该流域被列为长江流域水土保持综合治理试点后，制定了生态经济型防护体系治理规划、通过五年集中治理和五年巩固性治理，取得了显著成效，年均侵蚀模数降至６２０ｔ／ｋｍ２，森林覆盖率提高到７２％，人均纯收入增长近十倍，为同类型地区治理水土流失、提高环境容量提供了成功经验。

Sediment control structures for Gezhouba Hydropower Station

Based on numerous prototype data and model results, this paper sums up the experience in the design of sediment control structures for Gezhouba Hydropower Station.The main sediment control structures include the flushing sluices in the main channel, which are in service when the Yangtze river's discharge is more than 35 000 m3/s; the sand sluicing bottom outlets; the sedimentation control dyke; the sand control sill; and the power intakes of gentle bottom slope designed for decreasing the velocity of flow passing through them.The sand sluicing bottom outlets have the following functions: reducing the grain size and content of sediment in the flow passing through the turbines, scouring the sediment in front of the power intakes, drawing off the bed load of pebbles, scouring the sediment in the tailrace to lower the downstream level, and, increasing the generating water head when the sand sluicing bottom outlets are in service.