SWAT径流模拟及其对流域内地形参数变化的响应研究

SWAT(soil and water assessment tool)模型是一个集成遥感(RS)、地理信息系统(GIS)和数字高程模型(DEM)技术的基于水文过程的、具有较强物理机制的先进的分布式流域水文模型。为了进一步研究流域尺度内水文过程的时空变化规律,深入了解流域水文时空过程与气象、地—气界面条件及流域地貌特征间的关系,选取汉江上游马道流域,运用AVSWAT2000版模型进行1981—1985年间的年、月径流模拟,以月径流模拟的N—S模型效率系数为主要指标,率定出月模拟效果最佳时的各参数值。在此基础上从马道出水站点沿主河道往上游再选取6个控制点,运用River Tools软件提取出各个控制点控制流域和地形参数,分析参数变化情况,并在此基础上用前面率定好的参数来模拟各个控制点处的出口流量,分析径流对地形参数变化的响应关系,并提出了归一化径流—河道总长比指数。该指数受到河源密度的影响,在流域内的变化趋于常数1。

Responses of Runoff Simulations to the Change in Topographic Parameters Based on SWAT Model

Soil and Water Assessment Tool(SWAT) model is an advanced distributed hydrological model which is based on physics mechanism and integrated with Remote Sensing(RS),Geographic Information System(GIS) and Digital Elevation Model(DEM) techniques.In order to study temporal and spatial tendency of hydrological processes and find out a relationship among hydrological temporal and spatial process,meteorology and physiographic characteristics of river basin,yearly and monthly runoff simulations(1981-1985) were applied to Madao catchment located in the upper reaches of the Han River.After ascertaining the optimal parameters,satisfied simulation results were obtained with the accuracy of 0.9427 for Nash-Sutcliffe coefficient over the 5 year continuous monthly simulations on discharges,which suggest an excellent modeling performance of SWAT2000 in the study area.6 referenced sub-drainage basins were selected in the upper reaches of the Madao main river way,and topographic parameters were obtained using software of River Tools in each sub-drainage.Monthly runoff simulations were then applied to them with the same parameters as Madao catchment,the responses of runoff simulation to topographic parameters were studied,and the Normalization of Runoff-total Length Index(NRLI) were presented.Analyses indicate that NRLI is influenced by source density.NRLI fluctuates tempestuously as source density decreases sharply.Nevertheless,it still trends towards the constant 1 in Madao catchment.