Flood zoning in Golestan's rivers network using GIS

Flooding is a hazardous phenomenon that causes a great damage and loss to inland and coastal areas. Flood protection schems are employed to decrease the impacts of flood damage. The aim of this study is to measure the rate of flood hazard for all the flood plains located in Golestan province from discharges with different return period. After digitizing the maps and obtaining the digital elevation model (DEM), the characteristics of catchments and sub- catchments such as area, slope and the length of the main canal were obtained by using ArcView GIS software.Then, permeability specifications and the Land use of the watershed were obtained by using land use and permeability maps. Next, HEC-GeoHMS model was used using the prepared maps and data as described to obtain the CN of the basin. HEC-HMS model was simulated to obtain flood hydrographs with different return periods. From this, flood zonings for the threatened area at risk were specified. The results indicate that the Dough River sub-basin is more susceptible to flooding and has the highest flood rate. Using HEC-RAS Model and based on flood zoningmaps, the scales of collateral and infrastructural damages to towns and villages including roadsand building were estimated