网格大小选择对大尺度分布式水文模型水文过程模拟的影响

以都阳湖信江流域为研究区,分析了网格大小选择对大尺度分布式水文模型水文过程模拟的影响.研究结果显示,在同样参数条件下,1,2和4 km这3种不同尺寸网格对模拟的总径流量影响较小,但网格大小显著地改变着模拟水流在地表径流和地下径流间的分配;不同网格的模型计算的实际蒸发量的差别不显著;大网格的模型计算的地下水补给量大.经过率定后的3种不同网格的模型均能较好地模拟流域的径流过程,但2 km网格模型模拟的总体效果要好于1 km网格模型和4 km网格模型.研究表明,对于分布式水文模型,网格的精细并不一定提高模型的模拟效果,一定精度空间数据的翰人条件下,分布式水文模型存在一个合适的网格大小使得模型的模拟效果最佳.在流域水文模型的具体应用中,应考虑流域本身的尺度以及模拟的目的和精度要求,选择合适的网格大小,同时应结合模型机理,解释模拟结果.

Effects of Grid Size on Hydrological Process Model ing as a Distributed Hydrological Model at Large Scale

A grid-based distributed hydrological model (three different grid sizes : 1, 2, and 4 km) is used to study the impact of grid size on hydrological process modeling in a large catchment of Xinjiang River, China. Results from the study indicate that scaling of grid size absolutely affects the partition of water dist ribution between surface runoff and subsurface flow, with modeled base flow increasing obviously as grid size increases. Modeled annual stream flow shows a slight decrease as grid size increases. Scaling of grid size has no significant effect on actual evapot ranspiration of the catchment, but water infilt ration increases obviously when surface slope becomes flatter with a bigger grid size. After calibration, the three grid size models all have a well performance in modeling stream flow, but the 2 km grid size model performs better than the other two models. From this study, it can be concluded that fine resolution of grid size does not mean to improve the modeling accuracy in a distributed hydrological model and coarse resolution of grid sizes can be used for stream flow modeling, depending on watershed size and the level of accuracy required. For a specific resolution of soil data, there is an optimum grid size at which the model performs best .