Abstract: The procedure of flow confluence computation is difficult to be used for ungauged catchments because the flow confluence parameters are hard to obtain. In view of this, we applied spatially distributed unit hydrograph based on digital elevation model to the rainfall-flood model of Hebei province, and simulated four big floods in Yumenkou catchment. The application results show that the relative errors of flow rate of all flood peak are smaller than 5%, the error of peak time less than 2h and the effective coefficient larger than 0.85. The simulated results are in good consistency with the observed flood hydrographs. By combing spatially distributed unit hydrograph with the rainfall-flood model, we could solve the problem of flood early-warning in ungauged catchments, especially middle and small catchments in hilly areas.

Key words: rainfall-flood model of Hebei province, infiltration, spatially distributed unit hydrograph, flow concentration, simulation