桥子沟流域“1987．4．19”暴雨洪水及土壤侵蚀调查分析

Investigation and Analysis on "1987. 4. 19" Storm. Flood and Its Coursed Soil Erosion in Qiaozigou Watershed

桥子沟流域属黄土丘陵沟壑区第三副区。１９８７年４月１９日，该流域突降暴雨，造成了严重的水土流失。此次暴雨降雨集中、历时短、强度大，所形成的洪水历时短、峰值大。土壤侵蚀调查分析结果表明，本次暴雨造成该流域坡面总侵蚀量２０１９０ｔ，平均侵蚀模数为８７３８ｔ／ｋｍ２；造成该流域沟道总侵蚀量７０８７ｔ，侵蚀模数为５０８６０ｔ／ｋｍ２；坡面和沟道侵蚀量所占比例分别为７４％和２６％。效益计算结果表明，与坡耕地相比，人工草地、人工林地和水平梯田分别减蚀４３．０％、３４．４％和１００％，梯田的拦蓄效益非常显著．

Located at the third sub-district of the Loess Rolling Gullied Area, Qiaozigou watershedcreated serious soil erosion and water lose on 19 April 1987 when there was a sudden storm withmass rainfall, short duration, strong intensity. and then followed short time flood and high floodpeak. The soil erosion investigation and analysis showed that the storm had carried out total erosion of 20, 190 tons on the slopes of the watershed. and the average erosion modulus was 8, 738tons per square kilometer, the total erosion in the gullies was 7, 087 tons with average erosionmodulus of 50, 860 tons per square kilometer, the ratio of erosion on slopes and in gullies is 74%to 26%. The effect calculation indicated that the manmade grassland. forest and level terrace reduced erosion 43. 0%. 34. 4% and 100% respectively compared with the land on the slopes. Therefore, terrace is effective in reducing erosion and water conservation.