| The scientific planning of soil and water conservation is a premise of preventing soil erosion. The standard of planning and designing directly influence the implement of planning and the full exertion of integrative benefit of soil and water conservation. Land use and conservation measures should be configured based on the sustainable development, which adjust measures not only to local conditions but also to specified periods. But traditional planning usually takes long time to put to practice, and cannot reflect the result of planning for planners in time. Therefore, it is very significant to find new ways for soil and water conservation planning.Taking Xiannangou watershed as an example. According to the characteristics of planning specifications, through analyzing the trait of water and soil loss and land use spatial pattern of the watershed, we have studied soil and water conservation dynamic planning, and have drew several conclusions as follows:1) Establishment of the indexes of dynamic planning. We have put forward slope, plantation cover, soil erosion modulus, land-using types and conservation measures as planning indexes according to soil and water technology criterion and the actuality of soil erosion of Xiannangou.2) Put forward methods of the demarcation of priority prevention area and the grade of water and soil loss. Taking slope as studying unit, we have applied flexibly neural network to found the model of calculating slope erosion modulus. The erosion modulus of Xiannangou watershed has been confirmed that the average value is 2182.9 (t/km2 a) . The area of the commonly soil erosion account for 69.9% of the whole watershed, the area of medium soil erosion come up to 10.7% of the whole watershed and the area of the intense soil erosion amount to 19.4%. According to the principle of spatial self-association and fuzzy close degree, we have made out the demarcation of serious prevention area of Xiannangou. The area of the Defense Region is 1623.6 hm2 amount to 36.4% of the whole watershed, The area of the Monitoring Region is 1519.6 hm2, which come up to 34.1% of the whole watershed, and the area of the Priority Management Region is 1315.3 hm2, which account for 29.5% of the whole watershed.3) Put forward the methods of Land use and conservation measures planning and the theories of the fast prediction of water and soil loss. We have confirmed the concrete schemesof conservation measures of each field, through analyzing the trait of soil loss and calculating the erosion modulus on the various combinations of land use and conservation measures of each plot. The plantation and land use pattern will be changed with time after planning being put in practice. This will influence the trend of soil erosion of the whole watershed, which determines conservation schemes taken in the near future. Therefore, We have predicted the evolvement of water and soil loss of XianNan valley watershed with CA model. The model predicted that the percent of the overall area of above medium soil erosion will decrease from 50% to 11.9% in ten years if the planning land-use pattern were used.4) Put forward the methods for the evaluating of integrative benefit of soil and water conservation. A set of indexes of ecological and social-economical benefits have been set up for Xiannangou watershed. The weight values of ecological and social-economic benefits were calculated, respectively 83.3 and 16.7. The integrative benefits have been evaluated using AHP and GIS.Based on the above theories, we designed function frame of the soil and water conservation planning's system. But because of the lag characteristic of benefit evaluation and the limited time, only a part of the function of the system has been finished, the modification should be done in future. |
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