水利水保措施对延河流域侵蚀、泥沙输移和沉积的影响

以黄土丘陵沟壑区的延河流域为例,研究水利水保措施对流域侵蚀、泥沙输移、沉积过程的影响.水利水保措施能改变流域的侵蚀、泥沙输移和沉积过程,影响流域的泥沙收支平衡.分析表明:(1)20世纪70年代以来开展的大规模水土保持建设工程,使得延河流域的泥沙输移比显著下降,最小值为0.26;到80年代末,泥沙输移比有所回升,介于0.50~0.71之间;(2)泥沙输移比变化的主要原因,系流域内淤地坝、水库等沟道工程措施的拦沙作用所致,其波动变化主要受库坝质量及拦蓄库容变化的影响;(3)沟道措施的拦沙作用远大于坡面措施的减蚀作用,前者约相当于后者的1.68~16.98倍,因而坡面治理及相应措施尚有待加强.

Effects of Soil and Water Conservation Measures on Erosion,Sediment Delivery and Deposition in Yanhe River Basin

Based on a case study conducted in Yanhe River basin,a typical hilly-gully watershed located in the Loess Plateau,the decadal effects of soil and water conservation measures implemented in the basin on soil erosion,sediment transport,deposition process are analyzed.Soil and water conservation measures in the watershed have great influences on erosion,sediment transport and deposition processes,as well as the watershed sediment balance.The preliminary results show:(1) The sediment delivery ratio(SDR) has evidently declined due to the decadal large-scale erosion control measures implemented in the whole drainage area,reaching its minimum at 0.26 in 1970s and subsequently climbing up to 0.50~0.71 at the end of 1980s.(2) The dramatic decline of the SDR was caused by the ditch measures,i.e.,sediment-trapping check-dams and reservoirs,while the fluctuation of the SDR was apparently influenced by the quality and capacity of reservoirs and check dams.(3) The sediment interception effect of those ditch measures is 1.68~16.98 times as high as that of the sediment reduction with the slope measures,i.e.land terracing,tree-planting and grass-planting,indicating that those direct slope measures still to be improved.