土地利用变化下流域水沙产输变异研究

发布时间：2018-08-31 08:45

【摘要】：土地利用／土地覆被变化(LUCC)及其水文环境效应越来越受到国际学术界和各国政府的关注与重视,土壤侵蚀作为土地利用变化引发的主要环境效应之一,是引起土地退化、水库淤积、生态环境恶化的重要原因。对LUCC所引起的流域水沙产输规律进行定量研究,明确影响范围与程度,对认识人地关系,指导人类活动意义重大。长江上游地区在我国具有重要的生态地理位置,水土流失已经成为影响当地生态环境的重要问题。本文以澜沧江流域和嘉陵江李子溪流域为研究对象,基于SWAT模型构建了研究区域分布式水沙模型,对土地利用变化下流域水沙产输变异规律开展了定量研究,主要研究内容与结论如下： (1)研究了基于SWAT模型的流域分布式水沙模型构建方法,对基于DEM的水系提取与流域划分、水文气象数据库的建立与增补、土壤数据库建立、模拟方法选择、模型参数敏感性分析与设置、模型结果输出与分析验证等建模关键环节进行了阐述,重点论述了SWAT模型应用于论文所选流域时的技术方法。 (2)基于SWAT建立了澜沧江流域分布式水沙模型,对模型进行了率定与验证,率定期与验证期的月径流量Ens0.79,R20.82,月泥沙量E,s0.51,R20.72,模型能较好地模拟流域水沙过程。模拟了1975年和1985年两期土地利用下流域的土壤侵蚀量,结果表明澜沧江的中下游地区为易受侵蚀区域。选取土壤侵蚀量变化大的5个子流域,对子流域土地利用变化与土壤侵蚀量变化进行对照分析,结果表明子流域的土壤侵蚀量随着森林和草地面积的增加而减少。定义了土壤侵蚀增长量参数评价坡度对土壤侵蚀的影响,结果表明土壤侵蚀量随着坡度的增加而增大,治理坡度25°的耕地对防治水土流失作用明显。 (3)基于SWAT建立了嘉陵江李子溪流域分布式水沙模型,对模型进行了率定与验证,率定期与验证期的日径流量Ens0.52,R20.78,日泥沙量Ens0.51,R20.72,表明SWAT模型在中等尺度的区域上也具有良好的适用性。以李子溪流域1986年土地利用格局为基础,采用极端假设法对不同种植状况下的土壤侵蚀量进行了研究,模拟结果表明该区域种植小麦侵蚀量最小,种植红薯、玉米和油菜侵蚀量依次递增,混合种植的侵蚀量介于之间。研究了坡度对土壤侵蚀的影响,得出了与澜沧江类似的结论；模拟结果表明,单就侵蚀量而言,治理1km2坡度大于25°的耕地与治理4.1km2坡度为5～15°的耕地或者治理1.8km2坡度为15～25°的耕地效果相当。 (4)采用情景模拟法研究了降雨与土壤对流域水沙产输变异的影响,结果表明,降雨量对土地利用变化引起的侵蚀量变化具有正相关关系,降雨量越大,土地利用变化引起的侵蚀变化量也越大；对不同土壤情景的模拟表明,下垫面为黄土时土地利用变化引起的侵蚀变化量最大,以下依次是黑土、红壤、紫色土。
[Abstract]:Land use / land cover change (LUCC) and its hydrological and environmental effects have been paid more and more attention by international academic circles and governments. As one of the main environmental effects caused by land use change, soil erosion is the cause of land degradation. Reservoir siltation, ecological environment deterioration of the important reasons. The quantitative study on the regulation of water and sediment production and transportation caused by LUCC is of great significance in understanding the relationship between man and land and guiding human activities. The upper reaches of the Yangtze River have an important ecological geographical position in China, and soil erosion has become an important problem affecting the local ecological environment. In this paper, the Lancang River Basin and the Lizixi River Basin of Jialing River are taken as the research objects. Based on the SWAT model, the regional distributed water and sediment model is constructed, and the variation law of water and sediment yield and sediment transport in the watershed under the change of land use is studied quantitatively. The main research contents and conclusions are as follows: (1) the method of constructing watershed distributed water and sediment model based on SWAT model is studied. The drainage system extraction and watershed division based on DEM and the establishment and supplement of hydrometeorological database are studied. The key links of modeling, such as the establishment of soil database, the selection of simulation methods, the sensitivity analysis and setting of model parameters, the output of model results and the validation of model results, are described. The technical methods of applying SWAT model to the selected watershed are discussed in detail. (2) based on SWAT, the distributed water and sediment model of Lancang River basin is established, and the model is determined and verified. The monthly runoff rate and monthly runoff of Ens0.79,R20.82, in the validation period are regular and verified. The model can well simulate the process of water and sediment in the watershed. The soil erosion amount in the watershed under land use in 1975 and 1985 was simulated. The results show that the middle and lower reaches of Lancang River are vulnerable to erosion. Five subbasins with large soil erosion amount were selected to compare the land use change and soil erosion change in sub-watershed. The results showed that the soil erosion decreased with the increase of forest and grassland area. The effect of slope on soil erosion is defined. The results show that the amount of soil erosion increases with the increase of slope. (3) based on SWAT, the distributed model of water and sediment in the Lizi River basin of Jialing River was established, and the model was determined and verified. The daily runoff (Ens0.52,R20.78,) daily sediment volume (Ens0.51,R20.72,) of rate periodic and verification period shows that the SWAT model is also applicable in the mesoscale area. Based on the land use pattern of Lizixi Basin in 1986, the soil erosion amount under different planting conditions was studied by extreme hypothesis method. The simulation results showed that wheat erosion was the least and sweet potato was planted in this area. The erosion amount of maize and rape increased in turn, and the erosion amount of mixed planting was between. The effects of slope on soil erosion are studied, and a conclusion similar to that of Lancang River is obtained. The effect of controlling cultivated land with 1km2 slope greater than 25 掳was equivalent to that of cultivated land with 4.1km2 slope of 5 ~ 15 掳or 1.8km2 slope of 15 ~ 25 掳. (4) the effects of rainfall and soil on variation of water and sediment yield and sediment transport in watershed were studied by using scenario simulation method. The results show that rainfall has a positive correlation with the change of erosion caused by land use change, and the larger the rainfall, the greater the change of erosion caused by land use change. The erosion change caused by land use change was the largest when the underlying surface was loess, followed by black soil, red soil and purple soil.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV14

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