论文部分内容阅读
流域系统可以分为坡面系统和沟道-河道系统2大单元,可以分别建立泥沙收支平衡关系。结果表明:1)实施水土保持措施以后,无定河流域系统泥沙收支平衡中各变量均随时间而变化。沟道-河道系统泥沙输移比发生了极显著的减小趋势,泥沙存储量发生了显著的增大趋势,流域产沙量的变化发生了较显著的减小趋势,坡面净侵蚀量有所减少,但变化趋势不显著。2)对于不同的泥沙收支平衡变量的变化而言,水土保持措施变化和降雨变化的贡献率是不同的;对坡面净侵蚀量的变化而言,汛期降雨的变化起着决定性的作用,贡献率高达90.82%,坡面水土保持措施的贡献率仅为9.18%;对沟道河道系统泥沙存储量的变化而言,淤地坝拦沙的变化起着决定性的作用,贡献率高达76.16%,汛期降雨变化的贡献率仅为23.81%;对流域产沙量的变化而言,汛期降雨和水土保持措施的变化都起着重要作用,前者贡献率为57.84%,后者贡献率为42.16%。3)对沟道-河道系统泥沙输移比RSDRc的变化而言,淤地坝拦沙的变化起着决定性的作用,贡献率高达87.27%,汛期降雨变化的贡献率仅为12.73%。
Watershed system can be divided into two major units: slope system and channel-river system, so that the relationship between sediment balance can be established respectively. The results show that: 1) After the implementation of soil and water conservation measures, the variables of sediment balance in the system of the Wuding River basin all change with time. The sediment transport ratio of channel-channel system has a significant decrease trend, the sediment storage volume has been significantly increased, and the change of sediment yield in the basin has been significantly reduced. The net erosion of the slope surface However, the trend of change is not significant. 2) The contribution rate of changes in soil and water conservation measures and rainfall is different for different variables of sediment balance. The change of rainfall in flood season plays a decisive role in the variation of the net erosion amount , The contribution rate is as high as 90.82%, and the contribution rate of slope water and soil conservation measures is only 9.18%. For the change of sediment storage in channel channel system, the change of sediment retention in check dam plays a decisive role, 76.16%. The contribution rate of rainfall in flood season is only 23.81%. For the change of sediment yield in flood season, the rainfall and the change of water and soil conservation plays an important role in the flood season. The former contributes 57.84% of the total, while the latter contributes 42.16%. 3) For sediment transport of channel-channel system, the change of silt-retaining dam play a decisive role, accounting for 87.27%. The contribution rate of rainfall in flood season is only 12.73%.