Abstract:
For physically based spatially distributed models which rely on a grid based representation of the spatial variability in a river basin, choice of an appropriate grid-size without compensating model performance is important. The present study examines the effect induced by three different grid-sizes (1, 2 and 4 km) on the model parameter values and performance in simulating streamflow and sediment yield using the shetran model applied to a humid tropical river basin, netravathi. First, the effective calibrated parameters of a 2 km model were applied to the 4 and 1 km model and the model performance was assessed. This indicated good monthly streamflow simulations at both grid sizes and a poor sediment yield simulation at 4 and 1 km, which demanded a recalibration. It has been observed that the grid size has a significant effect on various parameters. The effect of the finer grid-size was on reduction in sediment parameter values, mainly overland and channel erodibility coefficient, which were found to generate the most sensitivity for sediment yield. Further, the statistical indices (nse, r and pbias) after recalibration of the model with 1 km grid resolution were significantly improved. Hence, for the catchment under study, considering the model prediction accuracy (both streamflow and sediment yield) and the execution time, a 1 km grid-resolution is most appropriate. © 2020 international association for hydro-environment engineering and research.