Analysis on Variation of Runoff and Sediment Load of the Comparison Small Watersheds in the Third Sub-Region of Hilly and Gully Loess Region of the Loess Plateau

摘要

Water loss and soil erosion on the Loess Plateau has been a major concern for eco-environment conservation in China; so much attention has been paid to reducing water and soil losses.In order to understand the cause,development,and effectiveness of water and soil conservation measurements in the third sub-region of the hilly Loess Plateau,Tianshui Test Station of Water and Soil Conservation deployed a comprehensive soil erosion measurement system at East Qiaozigou Small Watershed (with comprehensive control) and West Qiaozigou Small Watershed (without comprehensive control) that were subject to the third sub-region of hills and gully area of the Loess Plateau.The measurement system was carried out following the idea of parallel contrast between the two comparison small watersheds.This system is the first comparison measurement system in China aiming at evaluating the effects of rainfall,runoff interception,water conservation and soil sediment measurement.More than 20 years' soil and water conservation observation data has been collected since 1985.By analyzing the characteristics of annual soil erosion with statistical methods,this paper developed the relationships between rainfall and runoff,rainfall and soil erosion,as well as runoff and sediment yield,in addition,researched the runoff-sediment transport process in the single flood event.This paper also gives systematic analysis on the effects of water and soil conservation practices based on Water Conservation Regulation.The paper also discussed overall effects of the measurements on the small watershed areas and soil erosion improvement caused by different water conservation methods.The results of this study will be of great value and will provide important reference to the systematic investigation on soil erosion pattern,and eco-environment effects of water conservation measurements for small watersheds.