On the simulation of the effect of changing the use of urban land on basin flood rise (Case study: basin of Germi Town, Iran)

In recent decades, one of the major reasons for risen flood flows in Northwest of Iran has been the changes in land use and urban land development. The goal of this paper is to investigate the role of changing the urban land use on flood rise of drainage basins. In this study, HEC-HMS hydrological model was used to evaluate the impact of land use change on peak discharge and basin flood volume in Germi Town in the Northwest of Iran. The reason behind choosing this hydrological model is because of taking into account the weather conditions, soil characteristics, and land use in simultaneous condition. In this research, hydrologic soil group maps with the HEC-HMS model are calibrated and validated in terms of runoff-rainfal data. The obtained results divulged that due to changes in land use and rangeland degradation, flood peak discharge have increased in different return periods. In addition, the simulation of two scenarios; pre-development and post-development conditions and their effects on peak flood discharge and the river normal flow were performed.