An innovative approach of GSSHA model in flood analysis of large watersheds based on accuracy of DEM, size of grids, and stream density

Abstract Distributed modeling approach may have much better performance and accuracy compared with lumped-parameter hydrologic models. The main goals of this research are: investigating the possibility combining distributed hydrological models an one-dimensional hydraulic model simulating waterways in large watersheds limited data. Then performing sensitivity analysis on different parameters order to identify containing major influences results. In current research, innovative Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model, cross-sections all 414 3450 km 2 Karvandar watershed, used for flow routing calculations, are uniquely extracted. Then, effect three essential factors evaluated. These digital topographic cell size grid network, density streams, results GSSHA simulations. This watershed is located southeastern Iran, has a dry climate available Results showed that peak discharges obtained from developed based DEM spatial resolution 12.5 m, slightly (< 4%) lower than corresponding values ​​in 30 m resolution. fact confirms use no substantial effects simulation. Also, increased significantly (44% 57%) by increasing model. Furthermore, discharge sizes 100, 150, 200 (base model), close together. Comparing two coarser grids (250 300 m), significant differences observed, which indicated larger could induce errors