不同下垫面径流小区土壤水蚀特征试验研究

在延安燕沟试验区建立不同下垫面（裸地、荒草地、灌木林地）自然地貌径流小区，在天然降雨条件下，分析2a来的产流事件的径流量、产沙量、入渗率数据，发现其随次降雨变化呈现规律性变化。在相同雨强条件下，裸地小区的径流量最大，为荒草地的6倍，为灌木地的2．4倍，裸地远大于有林草覆被小区；同时裸地小区的产沙量最大时是灌木地的82倍，是荒草地的150倍，可见林草覆被大大减少了黄土坡地的土壤侵蚀；在各次降雨过程中，灌木地的平均入渗率为90％，荒草地的平均入渗率为85％，而裸露地的平均入渗率为60％且远低于林草覆被黄土坡地。

Study of Plot Soil Erosion Characteristic Under Different Underlying Horizon

Three original physiognomy plots(besides bare slope,grass slope and shrubby slope) were constructed in the Yaner watershed. The amounts of the runoff,erosion and seeping rate in different sections in two years were analyzed.The data were found to vary with different rainfall events. Under the same condition,the amount of runoff on bare slope was 6 times greater than that on grass slope,and 2.4 times greater than shrubby slope,which indicated that bare slope produced more runoff than other two.The amount of erosion on bare slope was 82 times greater than that on shrubby slope,and 150 times greater than that on shrubby slope.This suggests that grass and shrubby can greatly reduce soil erosion in the Loess Plateau.Seeping rate varies with all the rainfall events.Generally speaking,seeping rate on shrubby slope is 90%,grass slope,85%,and bare slope,60%.It is a comparative advantage in melioration of the Loess Plateau to grow grass or shrub.