【作者】 林经理；

【导师】 颉耀文；

【作者基本信息】 兰州大学 ， 地图学与地理信息系统， 2009， 硕士

【摘要】 文县山高坡陡,降水集中,暴雨频繁,土壤侵蚀严重,严重制约了农业生产和山区经济的发展,定量评价该区的土壤侵蚀状况是为其制定水土保持措施提供依据的迫切需求。传统的、定性的土壤侵蚀评价方法技术已无法满足快速、定量调查的需求,使用GIS(Geographic Information System)和RS(Remote Sensing)技术,结合土壤侵蚀模型评价和分析区域的土壤侵蚀成为目前的一种趋势。本文运用GIS和RS技术,结合修正的通用土壤流失方程RUSLE(The RevisedUniversal Soil Loss Equation),选取1992年、2006年和2008年分辨率为30m×30m的TM遥感影像评价文县的土壤侵蚀状况。在研究区48年日降雨量资料、土壤属性数据矢量图层、DEM数据、植被覆盖度、以及土地利用现状的基础上,确定基本评价单元为30m×30m,计算降雨侵蚀力、土壤可蚀性、坡长坡度、覆盖与管理因子和水土保持措施因子。计算研究区的土壤侵蚀模数后将土壤侵蚀分为微度、轻度、中度、强烈、极强烈和剧烈六个等级,并对土壤侵蚀的分布特征进行分析。得出如下结论:(1)文县1992年平均侵蚀模数为15923.06t/(km~2.a),土壤侵蚀分布以轻度侵蚀为主,其面积占总面积的26.737%;2006年平均侵蚀模数为9477.477t/(km~2.a),土壤侵蚀分布以轻度和微度侵蚀为主,分别占总面积的37.044%,29.305%;2008年平均侵蚀模数为26739.18t/(km~2.a),土壤侵蚀分布以轻度、中度和剧烈侵蚀为主,分别占总面积的23.028%、18.452%和21.269%。对比发现,2006年降雨量小,土壤侵蚀模数小;在降雨变化不大时,2008年由于人为活动加剧,耕地增多,植被覆盖度降低,土壤侵蚀加剧,土壤侵蚀模数上升。(2)微度侵蚀主要分布在山脊、地势平缓地段和河流两岸缓坡耕地;山脊周围到沟谷两侧地段的同一个坡面,土壤侵蚀强度等级由低到高分布;剧烈侵蚀主要分布在植被覆盖度不高而坡度大的地段、裸地和陡坡耕地;(3)位于研究区中部的尚德镇和丹堡乡,东部及东北部的梨坪乡、天池乡、桥头乡、临江乡、尖山乡和口头坝乡,位于北部,人口最多的中寨乡和堡子坝乡及与其接壤的石鸡坝乡和石坊乡,陡坡耕地面积大,土壤侵蚀以剧烈为主,水土流失严重;本文采用GIS、RS与RUSLE相结合的方法分析文县土壤侵蚀的时空分布特征以及土壤侵蚀的影响因素和控制因子,可为该区的水土保持和生态环境建设提供科学的依据。更多还原

【Abstract】 With steep slopes, high mountains, concentrated rainfalls, frequent rainstorms, Gansu Wen County is gravely constrained on agricultural production and economic development by its serious soil erosion. To make effective soil and water conservation measures, quantitative evaluation of its soil erosion situation is urgently needed. Traditional, qualitative evaluation methods and techniques of soil erosion are unable to meet the need of rapid, quantitative survey. Using GIS (Geographic Information System) and RS (Remote Sensing) and combining with soil erosion model to study and explore is an inevitable trend.This paper uses GIS and RS, combining with RUSLE (the Revised Universal Soil Loss Equation), to study the situation of soil erosion in Wen County. It chooses the TM remote sense images with 30mx30m resolution taken in 1992, 2006 and 2008 respectively. On the basis of the daily rainfall data, the vector data tiers of soil, the DEM data, the vegetation coverage and the land use in the studying area, the basic cell to be evaluated is defined as 30m×30m area and the RUSLE factors including rain erosivity (R),soil erodibility (K),cover and management factor(C) , slope length-slope (LS) and supporting practice factor (P) are calculated. Then, the type and grade of soil erosion is ascertained. The soil erosion is scaled into six levels: tiny erosion, light erosion, moderate erosion, serious erosion, mighty erosion, and ultra erosion. The passage also analyses the distributing character of soil erosion. The conclusions are as follows:1、In 1992 , the average soil erosion modulus is 15923.06t/(km~2.a), and the main erosion is light erosion which takes up 26.737% of the whole erosion area. In 2006, the average soil erosion modulus is 9477.477 t/(km~2.a). And the main erosion is light erosion and tiny erosion, and theirs area take up 37.044% and 29.305% of total area respectively. In 2008, the average soil erosion modulus is 26739.18 t/(km~2.a).And the main erosion is light erosion, moderate erosion and ultra erosion, and theirs area take up 23.028%, 18.452% and 21.269% of total area respectively. By contrasting, the rainfall in 2006 is small, and the soil erosion is tiny; during the period of changeless rainfall, because of the increasing human activity, the expanding of farmland and the reducing of vegetation, the intensity of soil erosion becomes heavier and the soil erosion modulus is larger.2、Tiny erosion and light erosion mainly distributes in mountain ridge, valley, flat terrain and farmland besides rivers; Erosion types from mountain ridge to beside valley are tiny to ultra; Ultra erosion mainly distributes in area with low vegetation coverage but steep slope, unused land and farmland with steep slope.3、Shangde Zhen and Danbu Xiang located in the center of the research area, Liping Xiang, Tianchi Xiang, Qiaotou Xiang, Linjiang Xiang and Koutouba Xiang located in the eastern or north-eastern of the research area, Zhongzhai Xiang, Buziba Xiang, Shijiba Xiang and Shifang Xiang locatd in the northern of the research area, having huge farmland area with steep slope and with serious soil erosion, take serious erosion as main erosion type.This paper uses GIS and RS and bases on RUSLE model to analysis the space-time distribution characteristic and the influence factors and control factors of erosion in Wen County. It will provide scientific basis for Soil and water conservation and ecological environment construction in this area.更多还原