流域分布式水文模拟中的模型网格尺度效应

Effect of Grid Size on Distributed Hydrological Modeling

分布式水文模型建模过程中,DEM网格大小选择非常重要.以美国伊利诺伊河流域为例,分析了DHSVM模型DEM在多尺度下(100m×100m、200m×200m和500m×500m)的洪峰、洪量、地表、地下径流等水文要素和参数敏感性的响应.结果发现,网格大小对汇流影响较大,网格划分越大,洪峰流量增加,峰现时间提前,地表径流占总径流比例越大,网格水量滞蓄作用越大.研究还发现,模型参数在不同尺度下的敏感性也不相同,其中侧向传导率的参数尺度效应较大.为了得到合理的模拟效果,模型应用过程中需要考虑网格大小的影响,选择合适的网格尺度.

Grid size of digital elevation model （DEM） is very important in distributed hydrological modeling. This study is conducted in the Illinois River basin in the south central United States to analyze the effect of DEM on subsurface and surface runoff, flood peak, volume and model parameter sensitivity. The DEMs were gridded at 100, 200 and 500 m scales and the distributed hydrological soil-vegetation model （DHSVM） was used to evaluate the effects. The simulated results showed that DEM grid size significantly affected the hydro- logical modeling outcomes. It was observed that increase in grid size produced increase in peak flow and pro- portion of surface runoff to total runoff. The parameter sensitivity analysis also varies as grid cell changes. A- mong the model parameters, soil lateral conductivity was most sensitivity parameter. It is suggested that the appropriate DEM grid should be determined according to the required accuracy hydrological modeling.