Abstract:Through considering the effects of spatiotemporal transformations as well as watershed topography on runoff routing,this paper reports the development and implementation of the new method named spatially distributed time-variable routing method.The method incorporates time-variable factors into distributed yielding and routing simulations.In this way,it can overcome the shortcomings of ignoring the changes of excess rainfall over time in the traditional methods.Inaddition,with the support of the geographical information system (GIS) and remote sensing(RS),most of the parameters in the model can be obtained by means of DEM,soil maps and/or satellite images.Among the others,only some sensitive parameters need to be determined through calibration.Although the model seems to be simple,it can reflect the physical mechanism of rainfallrunoff process.In consequence,the method can predict the runoff hydrograph in the ungauged watersheds,so that it can be extended to other areas in the future.In the combination of this method with GIS technique,stream responses to runoff events in the Jiaokou Reservoir Watershed in Zhejiang Province were predicted.Results showed that the model efficiency was high,and the simulations were approximately consistent with the observations for the shapes of runoff hydrographs when the factor for the changes of excess rainfall over time was considered in the model.Most importantly, the floods can be identified by the shapes of each peak including the major and minor ones of all floods,especially of the double-peaks or multi-peaks flood,regardless of the rainfall intensity.