flood zoning estimation and river management by using hec-ras and gis model

reliable estimates of river stream fl ow and fl ood zoning maps are needed for water resourcesmanagement such as fl ood mitigation, water supply, dam construction and irrigation. flood zoning needsaccurate data and is one of the non-structural fl ood management methods. this paper describes theapplication of hec-ras and gis model to determine fl oodplains maps for the part of sardabrud riverthat lies in mazandaran province (iran). results obtained by hec-rac model were used in combinationwith gis to prepare fl ood zoning maps for different return periods. for this purpose, the geometrical planof the river was prepared with the aid of hec-ras software and through regional topography data. afterimporting the data to hec-ras model, fl ood phenomenon was simulated in 2, 5, 10, 50, 100, 500, and1000 years return periods. through fl ood zoning maps, areas that are vulnerable to fl ooding hazards havebeen identifi ed. analysis of fl ood zoning maps indicated that more than 168 square kilometer is likely to beinundated as compared to the normal fl ow of the river. also results of the current study indicate that depthof fl ow is happened in 1000-year return period and 163 meters respectively.