Research Of Soil And Water Conservation Benefit In Term Of Sediment Reduced In The Stream Based On GIS For Small Basin

The soil conservation benefit has always been the important part in soil and water conservation research. The soil conservation benefit of Jialing River basin has always been paid attention. Clarifying the soil conservation benefit of Jialing River basin will provide more evidences for further management of "Changzhi" project. In this research , through the on-the-spot investigation in Heminguan basin in highland area which was covered with purple soil in Sichuan province, soil sampling and indoor analysis and the analysis for the long term hydrological records of Hemingguang basin and the runoff plots which was set in the basin, basing on the full summary of former research achievement, specially on the research achievement which was focus on the benefit of the Jialing River basin, we focused on making clear the benefit of soil and water conservation of No.2 watershed of Hemingguan basin by carefully analyse through both the soil and water conservation method and hydrological method. In addition, the benefit analysis adopted the terrain factor analysis function of Geographic Information System(GIS) and basing on evaluation the effect of the slope variation on the index system of traditional soil and water caonservation method.We established a new soil and water conservation indices system.It was a good supplement for the traditional soil and water conservation method which set up indices system only from plot of one sole slope; Our new method well solved problem of tridional method which was unable to measure the effect of big rang slope variation in the benefit anlysis of soil and water conservation in south china. The main conclusions of this research are as follow:First, by adopting the slope variation condition into the method of soil and water conservation, the soil and water conservation benefit in term of sediment reduced in the stream of the forest land was 166.7t/a, the benefit of grassland was 37.8t/a. These benefits were remarkably higher than those obtains directly from the sole slope plot with traditional soil conservation method.Second, after 6 years soil and water conservation control,from 1991 to 1996, the annual soil and water conservation benefit in term of sediment reduced in the stream which measured by hydrological method was 229.8t/a, benifit radio was reached 76.4%. There was a good relationship between annual rainfall quantity and the amount of soil erosion of the basin, its regression analysis relevance was remarkable.Third, The soil and water conservation control benefit of No.2 watershed in Hemingguan basin, which measured by soil and water conservation method was...