Abstract:

Some improvements have been made to the original TOPMODEL，a semidistributed hydrological model based on subcatchment scale，with the consideration of the spatial variability of topography，underneath conditions and watershed climate.Significant improvements to the TOPMODEL were made on the distributed computation of runoff yield in the mesh scale which is equivalent to that of DEM in one hand，and an isochrones hydrograph was calibrated from rainfallrunoff observations for watershed convergence simulations on the other hand.These improvements were made to enhance the simulation ability of the TOPMODEL，meanwhile to extend the model′s adoptability in rainfallrunoff simulations to middle and large scale watersheds.The improved TOPMODEL were used in Lianghekou basin (2 818 km2) to simulate daily volume of runoff in this catchment，and a satisfactory simulation result with 70% or so in prediction precision was achieved.Further analysis on this model suggested that there were still ample rooms remained for further advancements.

Key words: TOPMODEL, Isochrones Hydrograph, DEM, Lianghekou Basin