不同土地利用背景下三峡库区土壤侵蚀模拟

发布时间：2018-04-10 13:05

本文选题：三峡库区 + 土壤侵蚀　；参考：《重庆师范大学》2017年硕士论文

【摘要】：三峡大坝作为世界大型水利工程之一,它的建设形成了三峡库区这一特殊区域。本区地处长江上游末端,不仅关系到三峡工程的安全,更是关系到长江流域生态安全的重要生态屏障区。三峡大坝的建设以及随之而来的城镇迁建、移民安置必定会对本区的地表形态造成扰动,进而对区域土地利用及气候环境造成影响从而影响到水土流失过程。土壤侵蚀及其导致的一系列环境问题是世界性主要环境问题之一也是该区所面临的最为严重的环境问题。土壤侵蚀导致大量的泥沙直接入库,淤积将大大缩减水库有效库容、缩短三峡电站寿命的同时引发和加剧长江流域洪灾。本文基于3S技术,采用通用土壤流失方程RUSLE对三峡库区1990-2010年间5个年份土壤侵蚀进行计算,并对研究区1990-2010年的土壤侵蚀强度时空变化、不同土地利用背景下的土壤侵蚀强度时空变化及分布规律进行定量分析,为三峡库区的可持续发展提供支持。最后基于三峡库区1990年侵蚀降雨特征,利用BP神经网络对2010年75个站点降雨侵蚀力进行模拟、验证,在此基础上,预测2030年75个站点降雨侵蚀力。选取2030年预测结果中位于库区周围的28个站点降雨侵蚀力进行Kriging插值,结合2030年库区自然增长、生态保护情景下土地利用模拟数据,基于修正土壤通用流失方程(RUSLE)计算2030年库区土壤侵蚀强度。结果表明:(1)1990-2010年三峡库区平均土壤侵蚀模数与土壤侵蚀量总体上呈现减少的趋势,多年平均土壤侵蚀量为18356.45万t,属于中度侵蚀;从空间上看,土壤侵蚀整体空间分布结构具有不平衡特征,主要表现为由东向西逐渐减小的趋势,研究区微度、轻度侵蚀等级分布面积最广。(2)1990-2010年间水田、草地面积有所下降,水域、建设用地呈现不断增长的趋势。库区建设用地的土地利用变化动态度增速最快,其次是水域。水田与旱地的相互转换、水田旱地的转出与转入、林草地的互换、林地与草地的水体淹没是1990-2010这20年间库区土地利用转换的主要方式。(3)6种不同土地利用在同一年分内土壤侵蚀强度指数:旱地草地林地水田建设用地;各土地利用类型微度侵蚀的面积逐渐增加,中度侵蚀及其以上的侵蚀等级的侵蚀面积都不同程度的向低等级转移;土地利用类型之间的转化对土壤侵蚀产生的深刻的影响,特别是造成土壤侵蚀的跨级突变,林草地的开垦、水田的旱种会造成土壤侵蚀强度的升高,耕地的退耕还林坏草,草地转换成林地导致土壤侵蚀强度的降低。(4)2010年库区降雨侵蚀力的平均模拟相对误差为15%,测试样本数据相对误差为14.67%,预测相对误差为19.65%,NE系数为0.85,说明BP神经网络对库区降雨侵蚀力具有良好模拟效果;2010年库区土壤侵蚀强度的Kappa指数为0.75,总体计算结果能满足模拟与预测需求。(5)在土地利用不变情况下,2030年库区轻度、中度侵蚀面积均有所增加,微度侵蚀面积及强度以上侵蚀面积均呈减少趋势,且侵蚀强度转变中的58%来源于相邻侵蚀强度,跨侵蚀等级区的较少;在降雨侵蚀力不变情况下,自然增长、生态保护情境下未来土地利用变化所导致的土壤侵蚀均呈下降趋势,后者土壤侵蚀下降的趋势更为明显;在降雨侵蚀力及土地利用均变化的情况下,自然增长、生态保护情景下土壤侵蚀均呈下降趋势。
[Abstract]:The Three Gorges Dam as one of the world's large water conservancy project, its construction has formed a special area of the Three Gorges Reservoir area. This area is located in the upper reaches of the Yangtze River at the end, not only related to the safety of the Three Gorges project, it is related to the important ecological barrier area of ecological safety of the Yangtze River. The Three Gorges dam construction and the urban relocation, resettlement must will cause disturbance to the area of the surface morphology, and the regional land use and climate impact which affects the process of soil erosion. Soil erosion and caused a series of environmental problems are global to the most serious environmental problems is facing environmental problems is one of the area. The soil erosion resulting in a large number of sediment directly storage, will greatly reduce the effective capacity of reservoir sedimentation, shorten the life of the Three Gorges power station at the same time triggered and exacerbated by floods in the Changjiang River Valley. This paper is based on 3S technology. Using the universal soil loss equation RUSLE in Three Gorges Reservoir Area during the past 1990-2010 years, 5 years of soil erosion was calculated, and the strength of the temporal and spatial variation of 1990-2010 years of soil erosion in the study area, different background soil changes and distribution of erosion intensity temporal and spatial quantitative analysis of land use, to provide support for the sustainable development of Three Gorges Reservoir area. Finally, based on the characteristics of rainfall erosion the Three Gorges Reservoir Area in 1990, verified the simulation, erosion force on 2010 at 75 sites rainfall by using BP neural network, based on the 2030 forecast of 75 sites rainfall erosivity. Kriging interpolation erosion force of 28 sites located in the area around the reservoir from 2030 rainfall prediction results, combined with the natural growth in 2030, ecological protection scenario land use simulation data, revised universal soil loss equation (RUSLE) based on the calculation of soil erosion intensity in 2030. The results showed that: (1 1990-2010 years in Three Gorges Reservoir Area) average soil erosion and soil erosion modulus showed a decreasing trend, the average soil erosion amount was 183 million 564 thousand and 500 t, which belongs to moderate erosion; from the space, the overall structure is unbalanced spatial distribution characteristics of soil erosion, the main form is gradually decreased from East to west, the study area of micro, mild erosion area were the most widely distributed. (2) 1990-2010 years of paddy field, grassland area decreased, water area, construction land is increasing. The construction land dynamic degree of land use change increased the fastest, followed by water. Conversion between paddy field and dry land, paddy upland and turn into swap, forest and grassland, woodland and grassland in the water flooding is the main way of land use conversion in the reservoir area during the past 20 years. 1990-2010 (3) of 6 different land use in the same year that part of soil erosion intensity The number of dry grassland woodland: paddy field of construction land; the land use types slightly erosion area increased, erosion area and erosion and moderate erosion above the level of the different levels of transferring to the low level; the land use change type between the effects on soil erosion in the deep, especially caused by cross level mutations in soil erosion, reclamation of grassland and forest, upland paddy field will cause soil erosion intensity increasing, farmland returning farmland to forest and grassland into bad grass, woodland reduce soil erosion intensity. (4) the average rainfall erosivity in 2010 relative error is 15%, the test sample data prediction relative error is 14.67%. The relative error is 19.65%, NE coefficient was 0.85, indicating that BP neural network has good effect on reservoir simulation of Rainfall Erosivity in reservoir area; soil erosion intensity index was 0.75 Kappa in 2010, the total volume calculation result To meet the needs of the simulation and prediction of land use. (5) in the same case, 2030 in mild, moderate erosion area has increased, the micro degree erosion area and erosion area decreased, and the erosion intensity in transition from 58% adjacent cross erosion intensity, erosion grade area is less; the natural growth in the the rainfall erosivity unchanged, ecological protection, under the situation of future land use changes of soil erosion caused by decreased, which decreased the soil erosion trend is more obvious; the rainfall erosivity and land use change under the condition of natural growth, ecological protection scenario of soil erosion decreased.

【学位授予单位】：重庆师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S157.1

【参考文献】