Abstract:

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.

Key words: isochronous-cell, DEM, distributed watershed model, overland flow, SFR1