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 Lüergou basin with the area of 12.1 km2 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 Lüergou 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 Lüergou basin of loess areas, analyses of the correlation and multi-variable regression were used to discuss on the relationships between 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 multi-variable 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.