Study On Index System And Model For Soil And Water Conservation Planning In Loess Hilly Region

Study on index system and model is a basic job for soil and water conservation planning. It is also the prerequisite and basic approach of soil and water loss comprehensive assessment and soil and water conservation ecological environment construction. It is very important and significant for making a good soil and water conservation plan, and choosing suit measures to prevent soil and water loss according to the local conditions, especially in loess hilly region.Taking the loess hilly region as its object, choosing small watershed as its unit, the study systematically analyzes the previous correlative results about soil and water loss rules. The author makes an effort in how to choose indexes, how to define weight, how to quantify the indexes and how to establish a model. Based on the above study, the author synthetically appraises the soil and water loss situation of the Xiannangou watershed, and analyzes the main problem in its ecological environment construction, and point out the harnessing ways. The main results are listed as follow.1. According to the features of the loess hilly region, the nature and society factors are considered comprehensively and a set of index system, which can be used in soil and water conservation assessment and dynamic monitoring, is established following the principles of science, operation, independence, level and dynamic. The index system includes 15 indexes related to climate, soil, landform, vegetation, land utilization and economy population.2. Adopt AHP to calculate the weight of indexes. The result indicates that the main resisting factors of soil and water conservation in loess hilly region are ratio of slope farmland (weight 0.244), vegetation coverage (weight 0.18) and average slope degree (weight 0.116). It reflects the correctness of returning the dry upland to forest or grass land.3. By analyzing deeply the rules of soil and water loss, the contribution functions are set up to realize the indexes' quantification with the help of fuzzy mathematics theory. Based on this, the regional soil and water conservation comprehensive assessment model is established. In order to help the researcher find out the existing problems in soil and water conservation ecological environment construction, the commensurate coefficients are introduced here.4. Using the index system and model, the author assesses the soil and water conservation situation of Xiannangou watershed. Its index of soil and water conservation is 0.5390. The commensurate coefficients show that the vegetation condition is relative good, but its broken landscape, big slope degree, and irrational utilization of land, especially mass slope farmland,are the main causes of soil and water loss. Hereby the principles of soil and water conservation are put forward.