基于DEM的等流时单元法在大流域分布式水文模型中的应用

Isochronous-Cell Application in Distributed Hydrological Model of Large Watershed Based on DEM

等流时单元法是一种具有物理基础同时又非常简便的分布式流域汇流模型。若能应用于大流域,会显著提高大流域分布式水文模型的计算能力,可以扩展其在大流域分布式水文模型中的应用,降低其限制性。采用基于DEM的等流时单元法进行坡面汇流计算,即坡面汇流经河流两侧并入河道,河道汇流使用扩散波方程(USGS的河道汇流程序包SFR1),将其推广到大流域分布式水文模型的应用之中。该方法与二维坡面汇流的扩散波数值方程相比较,能够节省计算时间。在伊通河中下游较大流域上试用结果表明,农安站计算与实测流量的最大相对拟合误差为13%,模型月流量Nash-Sutcliffe效率系数为0.9。等流时单元法用于大流域分布式水文模型的坡面汇流是可行的。

Isochronous-cell method is a convenient method which has clearly physical basis for the calculation of watershed confluence.The calculation ability in distributed hydrological model of large watershed would be obviously improved if this method could be used.Overland flow was simulated by isochronous-cell method based on DEM,that is lateral overland flow run in the river from each side of the river,and river flow was simulated by diffusion wave equation. And then it is applied in distributed hydrological model of large watershed.The calculation time was largely saved comparing with the calculation time of diffusion wave numerical equation of the 2-D overland flow.A case study at Nongan hydrologic station in the watershed of the downstream of Yitong River shows that the maximum relative error of calculated and determined flow volume is 13% and Nash-Sutcliffe efficiency index of the model for each month is 0.9.The feasibility of this model was proved by the computation.The example shows isochronous-cell method is feasible to overland flow in distributed hydrological model of large watershed.