| In this study, by using remote sensing (RS) and geographic information system (GIS) technology, combined with the small watershed field survey, social survey data and laboratory experiments, through principal component analysis, filtering out the evaluation indexes of small watershed comprehensive management, and then, taking use of the analytic hierarchy process (AHP) to systematic analyse and scientific evaluate the ecological benefits, economic benefits, social benefits and comprehensive benefits of small watershed in recent 7 years. The main research results obtained are as follows:(1) In the year of 2010, ecological efficiency index is 0.51 higher than the year of 2003,which is 0.30, increased by 70%. Percentage of the forestry and grass coverage increased from 11% to 50%, the percentage of 2010 is 4 times more than the percentage of without treatment. Soil erosion modulus decrease by 950 t/(hm2·a) than that before treatment, eliminating the possible amount of potential soil erosion. Total management degree of soil and water conservation has been improved significantly, from less than 60% before treatment increase to the 98%, indicating that the engineering measures and plant measures of soil and water conservation play a significant benefit in the small watershed. Rate of animals stable breeding reach to 99% in 2010, substantially achieve all stable breeding, effectively protect the environment, and reduce the soil erosion. With the implementation of comprehensive treatment measures, soil organic matter content continuously increased by 6 times more than before, up to 0.06%. Soil water content decreased by 44% compared with that before treatment.(2) The economic efficiency index reach to 0.74, compared with before that increase by 25.4% after comprehensive management of small watershed. Per capita net income of farmers reached 2,500 yuan, double than before treatment. Total agricultural output value grows rapidly, in the year of 2005, which is a turning point for the valley's economic growth, increase by 30%, then, keep an average annual increase rate of 3%, total agricultural output value of small watershed has been to 1.69 million in 2010, increased by 69% compared with before. Input-output ratio from the hold the line state, reduced to 0.70 in 2010, reduced by 26%. Labor productivity of watershed raise by 30% than before, with the small watershed management measures went on, complete liberation of the labor productivity, leading to sharp rise in labor productivity. Land productivity was increased by more than 75%. The economic benefits of soil and water conservation which is mainly from soil and water conservation measures reach to 3.2209 million yuan.(3) Comprehensive management of small watershed to promote the local social benefit development, after treatment, the social index of small watershed reach to 0.43 that increased by 16.2% than before. Engel's coefficient of the small watershed decreased by 44.1% after treatment, from subsistence level before treatment reached a level of relative well-off now. Education level was increased by 1 time than before. Commodity rate of agricultural products was increased by more than 6% which is due to labor productivity and land productivity increased together in the basin. Infrastructure growth ratio raised 2%. After 7 years management of small watershed, it is not only to improve the ecological environment, but also improve people's environmental awareness, which is increased 1 times than before.(4) The overall efficiency index reached 0.6 after comprehensive management of small watershed, which is increased by 39.5% compared with before treament, it is indicated that comprehensive benefits of small watershed management are significant in recent 7 years. Comprehensive benefits has improved that caused by the effectiveness combination of ecological, economic and social benefits.
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