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为定量评价退耕还林工程建设的水土保持效益,以国家退跟还林工程建设的典型县域为研究对象,基于3S技术与RUSLE土壤侵蚀模型,分析评价了该县退耕还林前后土壤侵蚀的时空变化。结果表明:吴起县实施退耕还林后12年来,水土流失控制效果明显,较高强度土壤侵蚀的土地面积在大幅度减少。①退耕还林后土壤侵蚀分布以中度侵蚀最多,其面积占吴起县国土总面积的43.62%,而退耕还林前土壤侵蚀以极强度侵蚀为主,占吴起县国土总面积的42.76%②退耕还林后全县平均土壤侵蚀为5 285 t/(km2·a),属于强度侵蚀,其退耕还林前平均土壤侵蚀为9779 t/(km2·a),为退耕还林后的1.85倍,退耕还林后全县每年可减少土壤侵蚀量1 704万t③研究区未利用地平均土壤侵蚀模数为19 513 t/(km2·a)、陡坡旱地土壤侵蚀模数为12 449t/(km2·a),其侵蚀模数分别相当于退耕还林地平均土壤侵蚀模数2 458 t/(km2·a)的7.94倍和5.06倍,④研究区还尚需加强对中度以上侵蚀区的治理,才能更加有效地控制该地区的水土流失。
In order to quantitatively evaluate the benefits of soil and water conservation in the project of converting farmland into forestry, taking the typical county where the state retreats into construction the project of returning farmland to forestry as the research object, the spatial and temporal distribution of soil erosion before and after the conversion of farmland to forested land was analyzed and appraised based on 3S technology and RUSLE model. Variety. The results show that after 12 years of implementation of the conversion of cropland to forestland in Wuqi County, the effect of soil and water loss control is obvious, and the land area of high-intensity soil erosion is greatly reduced. ①The soil erosion distribution after returning farmland to forest was moderately eroded, accounting for 43.62% of the total land area of Wuqi County, while the soil erosion before returning farmland to forest was dominated by very intensive erosion, accounting for 42.76% of the total land area of Wuqi County. ② After returning farmland to forest, the average soil erosion in the county is 5285 t / (km2 · a), which belongs to intensive erosion. The average soil erosion before returning farmland to forests is 9779 t / (km2 · a), which is 1.85 Times that after the project of returning farmland to forest, the annual soil erosion can be reduced by 17.04 million tons in the study area. The unused average soil erosion modulus is 19 513 t / (km 2 · a) in the study area, and the soil erosion modulus is 14 44 t / km2 · a), the erosion modulus of which is equivalent to 7.94 times and 5.06 times of the average soil erosion modulus of 2 458 t / (km2 · a) in the conversion of cropland to forest respectively. (4) In the study area, Governance, in order to more effectively control the soil erosion in the area.