A nonlinear watershed concentration model of time-variable instantaneous unit hydrograph and its application

In order to increase the applicability of instantaneous unit hydrograph and improve the precision of flood forecast,based on the Nash instantaneous unit hydrograph(IUH) theory,a new model of time-variable instantaneous unit hydrograph(TVIUH) is proposed in the paper.This model has taken into consideration of the influence of nonlinear factors,such as the density of net rainfall and the spatial non-uniform distribution in given basin.And the comprehensive objective function is established as well to optimize the related model parameters by means of a genetic algorithm.The model is very simple and applicable.The flood forecast computation of Guanyinge-Shenwo cascade reservoir has been carried out as an example by using the TVIUH model.The results show that the proposed model(TVIUH) can take good account for the nonlinear factors of the runoff flow in the basin and precisely forecast the flood.The research provides a reliable reference for flood control of reservoirs.