The Characteristics and Cause Analysis of Erosion Sediment in Rainstorm - based Flood in the Compared Watersheds in Sub - area 3 of Loess Plateau -Taking the Storm on 'June 15,2001' in Gullies of Qiaozidonggou and Qiaozixigou as Example

摘要

The 2 compared watersheds, Qiazidonggou and Qiaozixigou 2 adjacent gullies, are the level 4 sub - branches of Yellow River located on sub - area 3 of Loess Plateau. Since 1988 the Qiaozidonggou has been taken into erosion control program , the Qiaozixigou has been as the contrast, meanwhile their soil and water data have been observed. This paper analyses the characteristics of the rainfall, flood and sediment of the 2 watersheds based on the data observed on June 15, 2001 and field survey. The conclusions are that, under the little difference condition of rainfall, the characteristics of runoff and sediment of the 2 watersheds are significantly different. Compared with Qiaozixigou, the cutting down rate of peak flood of Donggou is up to 66.9% , unit's area reduces flood amount 13,336 m~2/km~2, reduce sediment amount 8,534 t/km~2, the sediment decreased by 8, 534 t/km~2 in Qiaozidonggou. Although the variety trend of runoff and sediment in both gullies are the same, but the variety ratios in the Qiaozixigou are larger than that in Qiaozidonggou, the erosion modulus in Qiaozidxigou was 3.5 times of that in Qiaozidonggou. The reduction efficiency of flood and sediment are 59.9% and 79.5% respectively in Qiaozidonggou on contrast, that in Qiaozixigou are 6.9% and 8.4%, the erosion control measures in Qiaozidonggou bring into play of runoff and sediment reduction significantly.