黄土地区森林植被水土保持作用研究

 选取黄土地区不同森林植被1)类型的两组4个试验流域为研究对象，通过6年(1988～1993)近70场暴雨洪水的实地观测，对次暴雨(是指一场降雨从开始到终止这一时段)产沙量同森林植被的关系进行了定量分析，提出了含森林覆被率的5因子次暴雨产沙模型，进而对森林植被的水土保持效益进行了分析。木家岭小流域和庙沟小流域相比，无林流域的产沙量比森林流域高33.4倍，森林的拦沙效益达到96.80％；木家岭流域和庙沟流域相比，少林流域比多林流域产沙量高4.3倍，森林的相对拦沙效益可达75.53％。同时通过黄土地区森林植被减沙作用的分析，提出了森林植被的拦沙量计算公式，据此可以求得不同降雨条件下，对比流域森林植被的拦沙量。

SOIL AND WATER CONSERVATION BY FOREST VEGETATION IN LOESS AREA

During 1988～1993,about 70 times of floods were systematically observed in the sites located at 4 watersheds(in two groups) of different forest vegetation in Loess Area. Based on the data, the relationship among watershed sediment yield, the forest vegetation and the other 4 factors were investigated and modeled. Then the effects of forest vegetation on watershed sediment yield were analyzed using the model. The result shows that forest vegetation had a great role in yielding watershed sediment. The sediment yield in Miaogou small watershed (no forest vegetation) was higher by 33.4 times than that in Mujialing small watershed (with much forest vegetation). Its erosion control by forest vegetation was about 96.8%. The sediment yield in Miaogou watershed (with little forest vegetation) was higher by 4.3 times than that in Mujialing watershed (with much forest vegetation). Its erosion control by forest vegetation was about 75.53%. According to the analysis of erosion control effect by forest vegetation in loess area ,the erosion reduction formulas of forest vegetation were derived. Using these formulas,the reductions of watershed sediment due to forest vegetation under the conditions of different rainfalls can be calculated.