SWIM水文模型的DEM尺度效应

数字高程模型(DEM)极大地促进了分布式流域水文模型的快速发展。本文引入SWIM水文模型,以淮河上游长台关地区为研究区,将15种不同分辨率DEM数据输入水文模型,分析DEM分辨率对径流模拟的影响,并探讨最佳DEM分辨率选取及DEM分辨率对流域地形参数与径流模拟影响等问题。研究表明:(1)研究区水文模拟效果较理想DEM分辨率在90～120m之间,采用栅格面积与流域面积比值(G/A)小于0.05和"thousandmillion"经验公式作为DEM选取参考等均适用;(2)DEM分辨率下降,水文模拟纳希效率系数呈波动下降,分辨率超过250m后,虽纳希效率系数有所提高,但此时DEM已不能刻画真实流域特征从而造成假象;(3)15种分辨率DEM在水文极端事件模拟上差异较大,高纳希效率系数时不能较好地反映水文极端事件,尤其是峰值,而在枯水期15种DEM水文模拟效果均较好,DEM分辨率降低导致水文模型对降水等反应敏感。

Effects of DEM resolution on results of the SWIM hydrological model in the Changtaiguan basin

In this paper,the impacts of the Digital Elevation Model(DEM) with different resolutions on the simulation results of the SWIM hydrological model are examined for the Changtaiguan basin in the upper reaches of the Huaihe River basin in East China.Fifteen DEM resolutions(from resolution of 1000x1000 m to resolution of 30x30 m) are analyzed on their impacts on landscape parameters and runoff simulation results.Based on this,it is found that the best fitting DEM resolution in the study area is 90~120 m,and that both the ratio of Grid Area/Basin Area and the 'thousand million' formula are suitable methods.The Nash-Sutcliffe coefficients decline with DEM resolution;yet when DEM resolution is larger than 250 m,the Nash-Sutcliffe coefficients increase,because DEM grid is too coarse to display basin terrains.The simulation results of hydrological extreme events from 15 different DEM resolutions show a high variability.The high Nash-Sutcliffe coefficients do not reflect the hydrological extreme events,especially in the flood period.For the dry season,the simulation results of the 15 DEM resolutions show relatively good results.The results of the SWIM hydrological model are more sensitive to precipitation when the DEM resolution is decreasing.