Research On Topographic Wetness Index Based On High Precision DEM

The loess plateau area ecological environment is fragile,serious water and soil erosion has been one of the major environmental problems in the region has attracted much attention,while soil moisture is the restrictive factor of the loess plateau area ecological restoration reconstruction,which accurately describe the spatial distribution of soil moisture in the area of is particularly important.With the application of GIS and DEM in hydrology is becoming more and more popular,more and more research will be Topographic Wetness Index is applied to the description of the spatial distribution of soil moisture.Topographic Wetness Index can be used to quantitative simulation of soil under ideal state a point of dry and wet conditions,the index of In(SCA/tan ?)in the physical meaning can be expressed as the unit of catchment area and the slope of the composite function.In recent years,with the enrichment of high resolution DEM data and digital terrain analysis further broaden step by step,the research and application of TWI has been greatly developed,but in the Loess Plateau area,this research is not enough,need to be further expanded,in order for the ecological reconstruction in the loess plateau soil moisture simulation studies provide certain reference value.This paper selects the Yangou watershed and the Wang Maogou River Basin in the Loess Plateau as the research area,based on the high resolution 1m resolution DEM as the main data base,from the Topographic Wetness Index Algorithm,scale effect and micro topography(Ti Tian)to analyst the influence of the TWI to this study.The results showed that:(1)in the region of the Loess Plateau,mixed flow algorithm better balance to the loess plateau region unique dual terrain structure local morphological differences,it is more reasonable to simulate the surface runoff,to describe the spatial distribution of soil moisture content(2)to 1m,5m,10m,15m,20m,25m high resolution DEM as the foundation,with the decrease of DEM resolution,slope value decreases,and the unit water catchment area increases,the Topographic Wetness Index also increased.(3)Terraces built,which makes the slope by slowing down the increase of TWI value,have the effect of the reservoir water,but the data accuracy is not high expression of terrace information distortion,the TWI in the region of the terraces on soil moisture simulation there is a big discrepancy.The study is based on high precision data,in the hope of more accurate indicator of the loess plateau region spatial distribution characteristics of soil moisture and at the same time provides reference value for ecological environment reconstruction of soil and water conservation in loess plateau region.