【作者】 马建超；

【导师】 陈友飞； 林广发；

【作者基本信息】 福建师范大学 ， 地图学与地理信息系统， 2011， 硕士

【摘要】 地形湿度指数可定量模拟流域内土壤水分的干湿状况,是理想状态下静态土壤含水量的最常用指标,在流域的土壤侵蚀及分布式水文模型等研究中有重要意义。基于DEM提取的地形湿度指数,具有明确的物理意义,表示了在重力作用下不同地形水流运动的方向和趋势。但是由于DEM本身的结构特点,受到各种尺度的约束,因此利用DEM提取的地形湿度指数具有尺度依赖性。本文主要探讨了在不同DEM分辨率下两种地貌类型区地形湿度指数的尺度效应,以及由于DEM水平分辨率不同而导致的DEM栅格单元异质性对地形湿度指数提取的影响。分别以厦门地区地貌类型较复杂的西源溪流域以及地势平缓的内田溪流域为实验区,运用GIS、数理统计和空间分析等方法,研究分辨率分别为2.5、5m、10m、20m、40m、80m、160m的DEM所提取的地形湿度指数的误差特征与栅格单元异质性的关系。研究表明,在地势起伏较大的区域,基于高程标准差、地势起伏度、景观破碎度和多样性的栅格单元异质性指数与地形湿度指数偏差之间均存在良好的相关性；在地势平坦的区域,栅格单元异质性指数与地形湿度指数偏差之间的相关性弱。对此,可以用栅格单元异质性指数模拟复杂地形下较低分辨率的DEM提取地形湿度指数的误差,利用此拟合回归模型实现栅格单元异质性对较低分辨率的DEM提取地形湿度指数统计值的误差纠正,为其准确提取提供参考标准和依据。更多还原

【Abstract】 The Topographic Wetness Index (TWI) is frequently used to simulate the ideal soil moisture conditions in a watershed quantitatively, and it is the most commonly used indicator for watershed soil erosion and distributed hydrological model as well. The index that extracted from DEM is an important factor with explicit physical significance in the rainfall-runoff process models. It indicates the tendency of water that accumulates or flow out in different terrain area. Some previous studies discovered that the TWI will change with the resolution of DEM from which it was derived, so the TWI depends on the DEM scale. This paper explored the resolution effects of the TWI and the influence of terrain heterogeneity of DEM grids among different resolution DEMs for two different terrain regions. The research area was located in Xiyuan and Neitian watersheds. The terrain in Xiyuan watershed is rather complicated than the easy grade topography of Neitian watershed. A fine-resolution DEM with 2.5m grid size was used to research the scale dependency of TWI values when converting DEM with coarse resolution using GIS, mathematical statistics and comparative analysis and other methods. The results indicated significant correlations between the terrain heterogeneity indices and the TWI variance in Xiyuan watershed. So, these indices can be used to evaluate the impact of the terrain heterogeneity on the TWI for the topography fluctuation area. By extrapolating the fitted curve for the terrain heterogeneity indices and TWI variance, the regression models can improve the accuracy of the TWI derived from a coarse resolution DEM. The effect discussed in this study is helpful in providing a more accurate data for the TWI applications.更多还原