Flood Generation Potential and Flood Producing Area Determination Using ArcGIS Software and ModClark Model in Talar Watershed

Prioritization of sub-watersheds and different areas has an important effect in watershed management. The purpose of prioritization of sub-watersheds is to provide a pattern for control and decrease flood hazards and evaluating the role of each sub-watershed in peak discharge of outlet flood hydrograph. In this study, Talar watershed was selected as study area, because of several floods was occurred in it and then factors affecting floods like rainfall hyetograph for different return periods, flow length, slope percentage, land use, soil hydrological group, amounts of CN and time of concentration were recognized. By combining ArcGIS software and ModClark hydrological model, the potential of flooding in Talar watershed classified into five classes: Very Low, Low, Medium, High and Very High within three return periods of 25, 50 and 100 years. The results showed that the contribution of sub-watersheds in flooding potential will be not only affected by its area but also the location of each sub-watershed and flood routing in main reach have remarkable effect on flooding regime of the watershed. Runoff production potential maps indicate that runoff production potential from downstream to upstream of the watershed is increasing and Chashm sub-watershed in Southeast of the watershed is considered as the most effective area and unit in flooding of the whole watershed because of heavy rainfall, high slope and large curve number (CN).