黄土地区小流域植被覆盖和降水对侵蚀产沙过程的影响

Effects of vegetation cover and precipitation on the process of sediment produced by erosion in a small drainage basin of loess region

以1982—2000年吕二沟地区的水文气象观测资料与遥感资料为数据源，进行流域产沙强度与径流指标、降水指标、植被覆盖指标之间的相关与多元回归分析，结果表明，流域产沙强度随径流指标、降雨指标的增加而增大，随植被覆盖指标的增加而减小。为了区分人为因素与自然因素对侵蚀产沙的影响，采用对数据进行标准化处理之后再进行多元回归分析的方法，来确定相对贡献率。结果表明，植被盖度和降水变化对吕二沟流域土壤侵蚀量变化的贡献率分别为45．7％和54．3％，可见土壤侵蚀量受降水的影响要略大于受植被覆盖的影响。

With growing concerns on changes of the living environment and ecological environment, more and more scholars have focused their researches on understanding how vegetation covers and atmospheric conditions respond to soil erosion in drainage basins. And former studies showed that both the natural factors such as precipitation, vegetation, slope of terrain, soil properties and human activities were the main factors to affect the amount of Sediment Produced by Erosion in the water basin. And there were special conditions of climate and soil that were unique to loess areas for works of water and soil conservations. So the relationships between soil erosion and vegetation ＆ precipitation were very complicated and interesting. As a loess area, the Luergou basin with the area of 12.1 km^2 lies in west of China. The basin was a key area of high water and soil erosion forty years ago, but the area of vegetation cover became larger and larger because of highly effective works of water and soil conservation. In the factors affecting the amount of sediment produced by erosion in the study area, which was more important for soil erosion ： vegetation cover or precipitation？ This question has been discussed in the expert＇ s community since long time. And the Ltlergou basin was the natural and ideal test basin.Based on water observation data, climate data and NOAA/AVHRR NDVI images collected from 1982a to 2000a in the Luergou basin of loess areas, analyses of the correlation and multi-variable regression were used to discuss on the relationshipsbetween the amount of sediment produced by erosion and water indexes, precipitation factors and vegetation cover. The conclusions showed that with the increase of precipitation indexes, with the decrease of plant indexes, the amount of sediment produced by erosion in the study area would become larger.In order to distinguish in the influences of erosion between human activity and natural factors, the paper introduced the multivariable regression method by the standardization data to determine the relative contributing ratio to soil erosions in the study area.The conclusions showed that the contributing ratio of vegetation cover and precipitation changes were 45.7 % and 54.3 %. It was obvious that the influences of precipitation were larger than those of vegetation for the soil erosion in the study area.