计算单元边长对分布式流域水文模型模拟结果的影响

Influence of calculation unit size on simulation results of distributed watershed hydrological model

具有物理基础的分布式流域水文模型通常采用DEM栅格作为计算单元,对地形信息具有均化作用,使得提取的坡度为非真值,且不同尺度栅格对应的该非真值差别明显,导致基于不同计算单元边长分布式流域水文模型的模拟结果具有显著差异。为了解决不同分辨率DEM模型对于模拟结果的影响,提出了一种栅格尺度与提取的流域坡度之间关系的归一化表示方法及对应的坡度矫正方法,该矫正方法中引入了可用于模型流速计算公式的坡度矫正系数。研究结果表明,计算单元边长对模拟结果的影响规律与对提取的流域坡度的影响规律完全一致,且提出的方法可以有效消除栅格均化作用对分布式流域水文模型模拟结果的影响。

Distributed Watershed Hydrological Models with physical basis usually use the DEM grid as the calculation unit,which can homogenize the terrain information so that the extracted slope is non true value,and the non true value corresponding to different scale grids is significantly different,which leads to significant differences in simulation results based on different scale distributed models.In view of the influence of different resolutions on the simulation results,a normalized expression method of the relationship between grid scale and the extracted watershed slope and the corresponding slope correction method are proposed.The slope correction coefficient which can be used in the calculation formula of model velocity is introduced in the correction method.The results show that the influence of cell size on the simulation results is consistent with that on the extracted watershed slope,and the proposed method can effectively eliminate the influence of grid equalization on the simulation results of distributed hydrological model.