甘肃天水市对比小流域暴雨洪水侵蚀产沙特性

Comparison of storm runoff and sediment yield between two different managed small watersheds in the Loess Plateau

为分析黄土丘三区水土保持综合治理对小流域典型暴雨产汇流特性的影响,依据桥子东、西沟对比小流域暴雨洪水泥沙观测资料,结合实地调查对比分析雨、洪、沙特性。结果表明:在降雨差异很小的情况下,其水沙特性差异明显,桥子东沟较西沟洪峰削减率达66·9%,单位面积减洪量1万3336m3/km2,减沙量8534t/km2,2流域的流量和含沙量过程变化趋势基本一致,但西沟变率均大于东沟,且西沟流域侵蚀模数是东沟的3·5倍。桥子东沟流域各项水土保持措施发挥了显著的蓄洪拦沙作用,减洪效益59·9%,减沙效益79·5%;桥子西沟的林草措施减洪效益为6·9%,减沙效益8·4%。

On the basis of observation from paired-watersheds, named Qiaozidong and Qiaozixi wateshed, the characteristics of rainfall, runoff and soil erosion between the paired watersheds were studied. The results show that Qiaozidong watershed with better soil and water conservation measures coupled with improved vegetation cover has, on the premise of the same storm event, demonstrated by strong capacity of reducing flood peak flow and sediment yield. It was found that the runoff production of Qiaozidong watershed was decreased by 13 336 m^3/km^2, and sediment yield descended by 8 534 t/km^2, compared with those of Qiaozixi watershed. Furthermore, the module of soil erosion on Qiaozixi watershed was 3.5 times of that on Qiaozidong watershed. In generally it is supposed that the effects on runoff and sediment yield reduction were mainly attributed to the well functionally soil and water conservation measures, as well as the increased vegetation cover.