【作者】 林斌；

【导师】 邸利；

【作者基本信息】 甘肃农业大学 ， 土壤学， 2011， 硕士

【摘要】 甘肃省定西市属于陇西黄土丘陵沟壑区,土地受气候、水文和地质等自然因素及人类不合理的开发利用影响,出现了不同程度的土壤侵蚀。本文以美国通用水土流失方程(USLE)所涉及的水土流失影响因子为基础,通过对降水、地形、土壤等因子的计算,采用RS与GIS相结合的技术手段,研究了该区域在过去16年来的土壤侵蚀时空分布格局及其变化特征,并对土壤侵蚀量进行定量估算并参照土壤侵蚀强度按照水利部“水力侵蚀强度分级标准”进行分级。在对土壤侵蚀量的定量估算研究过程中,利用遥感数据,获取水土流失的植被和土地利用信息,提取植被和人为措施因子;根据当地降雨资料和土壤数据,来计算降雨侵蚀力和土壤可蚀性因子;通过数字化地形图,提取高程线和高程点,建立数字高程模型DEM来进而求得研究区坡度和坡长因子,经过诸因子算式及监测模型运算,逐个计算出各像元的年土壤侵蚀模数,对研究区域土壤侵蚀定量估算。通过研究,获得以下主要结论:1、在1993年-2005年的12年中,轻度侵蚀、中度侵蚀分别净增147.11 km~2和1418.91 km~2,增加了4.05%和39%。而极强度和强度侵蚀面积明显减少,净减575.56km~2和799.8 km~2,减少了15.83%和21.98%,表明新增的中度侵蚀主要由强度侵蚀和极强度侵蚀转化而来,表明水土流失状况趋于好转。2005年强度侵蚀和极强度侵蚀主要发生于存在沟状侵蚀的北部高丘陵区,由于生态工程实施区域较小,自然因素与人为破坏共同作用,导致坡面径流冲刷和水土流失加剧。2、2005年~2009年微度侵蚀净增237.32 km~2,增加了6.52%,轻度侵蚀净增735.54 km~2,增加了20.22%,中度侵蚀和强度侵蚀面积净减918.47 km~2和57.7 km~2,减少了25%和1.58%,可喜的是2009年极强度侵蚀消失。总而言之,定西市安定区在1993年~2009年中的16年间水土流失强度整体上趋于慢慢减小。3、1993年~2009年中的16年间,土地利用类型中林草地大幅度增加,林草地由1993年494.22 km~2增加到1295.87 km~2,而植被覆盖度在45%~60%的由1993年453.75 km~2增加到1503.61 km~2,植被覆盖度在60%~75%的由1993年119.08 km~2增加到958.07 km~2,这些重大的改变要归功于定西安定区从2000年开始的退耕还林工程。最后,本研究成果可直接为定西市安定区的治理及土地的合理利用提供可靠的依据,具有实践意义。更多还原

【Abstract】 Dingxi City in Gansu Province belongs to Longxi Loess Plateau, and the land suffers from varying degrees of soil erosion due to impact of climate, hydrology and geology and other natural factors as well as of irrational development and utilization of human. To keep abreast of the development trend of soil erosion is the basic premise of establishment and implementation of ecological construction and environmental policies. Based on the remote sensing images, rainfall, topography and soil data in the objective area, the study investigated the spatial and temporal distribution patterns and variation of soil erosion in the past 16 years by using of GIS, RUSLE model, gave a quantitative estimation to the amount of soil erosion, and classified the soil erosion intensity in accordance with the "water erosion intensity classification standard" specified by Ministry of Water Resources. In the quantitative estimation of soil erosion, remote sensing data was used to get vegetation and land use information of soil erosion and extract vegetation and man-made factors of measures; rainfall data collected in the local area and soil data was used to calculate the rainfall erosivity and soil erodibility factor; elevation lines and elevation points were extracted through digital topographic maps, and digital elevation model (DEM) was established to obtain the slope and slope length factor in the area, and regional soil erosion model was set up to calculate the modulus of yearly soil erosion for each pixel individually through the various factors and monitoring model computation formula and to make a quantitative estimate on the soil erosion of the study area. 3S technology was used as the core technology, dynamic land degradation was carried out on land use, land-cover change and soil erosion, through series of studies, the following conclusions were obtained:1. Soil erosion intensity classification map generated in Anding District in Dingxi city clearly shows: in 12 years in 1993 -2005, slight erosion, moderate erosion has a net increase of 147.11 km~2 and 1418.91 km~2 respectively with increase rate of 4.05% and 39%, while the area that suffers from intense and extremely intense erosion was reduced, the net reduction is 575.56km~2 and 799.8 km~2,with the rate of 21.98% and 15.83%, indicating that the new moderate erosion mainly transformed from intense erosion and extremely intense erosion, indicating that all levels of erosion are turning towards the positive direction, and soil and water loss is getting better. Intense erosion and extremely intense erosion in 2005 occurred mainly in the northern high hilly areas with gully erosion, due to the region of ecological engineering is small, and coupled with interaction of natural factors and man-made destruction; erosion in the slope and runoff is getting worse.2. Slight erosion had a net increase of 237.32 km~2, with an increase of 6.52%, in 2005 and 2009; light erosion had a net increase of 735.54 km~2, with an increase of 20.22%, moderate erosion and intense erosion had a net loss of 918.47 km~2 and 57.7 km~2, reduced by 25% and 1.58%, and the good news is that extremely intense erosion disappeared in 2009. All in all, the overall intensity of soil erosion tends to be better in the 16 years from 1993 to 2009 in Anding District in Dingxi city.3. In 16 years from 1993 to 2009, in terms of land use types, forest and grassland have a huge increase from 494.22 km~2 in 1993 to 1295.87 km~2, while the land with the vegetation coverage between 45% and 60% increased to 1503.61 km~2 from 453.75 km~2 in 1993, the land with the vegetation coverage between 60% and 75% increased to 1503.61 km~2 from 453.75 km~2 in 1993, which is due to the long-term mechanism for returning farmland to forest project since 2000.Finally, the results have practical significance since they can directly provide a reliable basis for to management and rational use of land in Anding District in Dingxi City.更多还原