坡沟系统侵蚀产沙特征模拟试验研究

Experimental study on the sediment yield characteristics in slope-gully system

坡沟系统介于坡面尺度和流域尺度之间,揭示其侵蚀产沙特征对于认识流域侵蚀产沙及建立流域土壤侵蚀预报模型有重要意义。采用放水冲刷法,通过2.125、3.205、5.250、7.185L/min4个不同的放水流量,在4m长坡面(坡度为20°)和3m长沟坡(坡度为50°)组成的坡沟系统上,对坡沟系统的侵蚀产沙特征进行了模拟试验研究。结果表明:对试验条件下的每一个放水流量来说,坡沟系统内的侵蚀产沙垂直分布都呈双峰曲线,侵蚀量的变化均呈现出沿坡沟系统从上到下先减小后增大再减小的趋势。沟坡部分的侵蚀量占全坡侵蚀量的百分比由放水流量2.125L/min时的38.13%,增加到放水流量7.185L/min时的56.01%。对于黄土高原水土流失治理,单纯治坡或治沟均不能明显减少土壤流失量,采取坡、沟兼治才是有效减少土壤流失的有效措施。

The slope-gully system is between slope scale and watershed scale. Revealing the sediment yield charaeteristies in the slope-gully system is very important to understand watershed erosion and sediment and build the sediment yield model of watershed. Taking the slope-gully system as the research object, which was composed of four meters long slope（20°） and three meters long gully slope（50°）, a series of simulated scouring experiments under the different flow discharges（2. 125, 3. 205, 5. 250, 7. 185 L/min） were conducted. The results show that the spatial distribution of erosion from the up-slope to down-slope shows a tendency of decreasing at the top of slope and increasing at the middle part of slope and decreasing at the lower part of slope. The erosion of each section in the slop-gully system from the up-slope to down-slope is closely related to the flow discharges and the flow rates. The larger the flow discharges and the flow rates, the larger erosion of each section in the slope-gully system. The ratio of the sediment yield on gully section to the total sediment yield in the whole slope-gully system increases from 38. 13%（at a flow discharge of 2. 125 L/min） to 56.01%（at a flow discharge of 7. 185 L/min） under the experimental condition. For the harness of the soil and water loss in Loess Plateau, only controlling the slope or gully will not reduce the sediment yield effectively. Comprehensive harness is the effective measure to reduce the sediment yield in Loess Plateau.