基于精细DEM的地形湿度指数研究

发布时间：2018-06-11 16:09

本文选题：精细DEM + 流向算法　；参考：《西北大学》2017年硕士论文

【摘要】：黄土高原地区生态环境脆弱,水土流失严重一直是该地区备受瞩目的重大环境问题之一,而土壤水分是制约黄土高原地区生态修复重建的限制性因子,因而准确描述该地区土壤水分的空间分布是尤为重要的。随着GIS和DEM在水文学中应用的日益广泛,越来越多的研究将地形湿度指数应用到土壤水分空间分布的描述当中,地形湿度指数可用来定量模拟处于理想状态下每点土壤的干湿情况,该指数In(SCA/tanβ)的物理意义可表达为单位汇水面积以及坡度的复合函数。近些年来,随着高精度DEM数据的不断丰富和数字地形分析的逐步深入拓宽,TWI的研究与应用已得到较大的发展,但在黄土高原地区,这方面的研究尚有欠缺,有待进一步拓展,以期为黄土高原的生态重建土壤水分模拟研究提供一定的参考价值。本文选取黄土高原地区的燕沟流域和王茂沟流域作为研究样区,以高分辨率1m分辨率的DEM为主要数据基础,从地形湿度指数的算法、尺度效应以及微地形(梯田)对TWI的影响这三部分着手进行分析研究。结果表明:(1)在黄土高原区域,混合流向算法较好的平衡顾及到黄土高原地区特有的二元地形结构的局部形态差异,更加合理的模拟地表径流,描述土壤含水量的空间分布。(2)以1m,5m,10m,15m,20m,25m高精度分辨率的DEM数据为基础,随着DEM分辨率的降低,坡度值减小,单位汇水面积增大,地形湿度指数同样也是增大。(3)梯田的修筑,通过减缓坡度从而使得TWI值增大,起到了蓄水保水的作用,但精度不高的数据对梯田信息表达的失真,使得TWI在梯田区域对土壤水分模拟存在较大出入。该研究以高精度的数据为基础,以期更精确的指示黄土高原地区土壤水分的空间分布特征同时为黄土高原地区的水土保持以及生态环境重建提供参考价值。
[Abstract]:The ecological environment of the Loess Plateau is fragile, and the serious soil erosion has been one of the most important environmental problems in the region, and soil moisture is the restrictive factor that restricts the ecological restoration and reconstruction in the Loess Plateau. Therefore, it is very important to describe the spatial distribution of soil moisture in this area. With the increasing application of GIS and Dem in hydrology, more and more researches apply topographic moisture index to describe the spatial distribution of soil moisture. The topographic moisture index can be used to quantitatively simulate the dry and wet conditions of soil at every point in an ideal state. The physical meaning of the index Insca / tan 尾 can be expressed as a composite function of the unit catchment area and the slope. In recent years, with the continuous enrichment of high-precision Dem data and the gradual deepening of digital terrain analysis, the research and application of TWI have been greatly developed, but in the Loess Plateau, the research on this aspect is still lacking and needs to be further expanded. In order to provide some reference value for soil moisture simulation of ecological reconstruction in Loess Plateau. In this paper, the Yangou basin and the Wang Mao valley in the Loess Plateau are selected as the sample areas. Based on the Dem with high resolution 1m resolution, the algorithm of the topographic humidity index is used. The scale effect and the influence of microtopography (terrace) on TWI were analyzed. The results show that in the Loess Plateau region, the mixed flow direction algorithm has a better balance, taking into account the local morphological differences of the unique binary topographic structure in the Loess Plateau region, and simulating surface runoff more reasonably. The spatial distribution of describing soil moisture content is based on Dem data with high resolution of 1 m ~ 5 m ~ 10 m ~ 15 m ~ 20 m ~ (25 m). With the decrease of Dem resolution, the slope value decreases, the unit catchment area increases, and the topographic moisture index is also increased. By slowing down the slope, the TWI value was increased, which played the role of water storage and water retention, but the distortion of terrace information was caused by the data with low accuracy, which resulted in a great discrepancy between TWI and soil moisture simulation in terrace area. This study is based on high precision data, in order to more accurately indicate the spatial distribution characteristics of soil moisture in the Loess Plateau and to provide reference value for soil and water conservation and ecological environment reconstruction in the Loess Plateau.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S152.7

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