基于GIS黄土丘陵沟壑区分布式侵蚀产沙模型的构建——以蛇家沟小流域为例

分布式侵蚀产沙模型是土壤侵蚀模型的重要发展方向,本研究将蛇家沟流域下垫面划分为5 ×5m的栅格,每个栅格内赋予相应的高程、坡度、地貌、土地利用等属性信息.根据流域DEM,确定流域的汇流方向、流路与汇流累积面积.在蛇家沟流域内采用“穷举算法”对SCS-CN模型的参数值进行校正.基于DEM、地貌、土地利用以及降雨等资料,利用黄土丘陵沟壑区良好的水沙关系,运用VB.NET+ARC ENGINE9.2+ SQLSERVER2000构建分布式侵蚀产沙模型.模型结构简单,输入参数比较少,利用求产流来求产沙,考虑了土地利用、汇流等因素具有一定的物理意义,并能达到一定的预报精度.其中产沙模型是建立在黄土丘陵沟壑区普遍的水沙关系基础上,通过校正水沙关系式系数及产流模型中的CN、λ值可在其它相似的小流域内使用.该研究可为黄土丘陵沟壑区水土保持治理效果评价提供依据.

A GIS-based distributed soil erosion and sediment yield model for typical watersheds in hilly loess areas:a case study in Shejiagou catchment

The study of distributed soil erosion and sediment yield models is a very important field of research on soil erosion models.As the natural conditions are inconsistent,the model divides a valley into a lot of grids,in each the soil,vegetation,slope,land use pattern,and rainfall are distributed equally and the parameters are the input in each grid.In virtue of the characteristics of runoff and sediment yield in loess hilly area,the Shejiagou watershed is divided into many grids(5m×5m),in each grid the inputs are the same(elevation,slope,physiognomy,land use).According to the elevation of grids,the direction,distance and area of concentration are confirmed.Through compiling code revising the parameters of scs-model in the Shejiagou watershed,based on the data of DEM,physiognomy,land use,rainfall and the relation between runoff and sediment yield in loess hilly area,and using VB.NET、SQL SERVER2000、ARC Engine9.2,a distributed soil erosion and sediment yield model is constructed with some traits as follows: simple structure,less parameters,sufficient factors such as land use,distinct physical significance,and high precision in prediction.This model setting is universal in hilly areas of the loess plateau,so it can be applied in similar watersheds through revising CN.This study can provide a reference for soil and water conservation in hilly areas of the loess plateau.