Estimating Flood potential of Kharashk basin by emphasize on Geomorphologic characters by using SCS method, Rudbar, Gilan Province

Flood is among phenomenon which brings about considerable damage each year. This has been attracted greatly by hydrologists. The factors such as physiography, geomorphology and human factors can accelerate this phenomenon in basins. For using water source, flood management, damming, watershed management and the most basic hydrologic studies, peak discharge is important, so accuracy of studies and the safeties’ level of the hydraulic structures and establishments are independent to it. In this research potential flood Kharashk basin were studied by using of SCS method. So Basin Hydrograph dimensions calculated by using of 24 hour rainfall, time of concentration, Curve Number, rainfall excess, time to peak and peak discharge. Then was design Hydrograph for basins in 2,5,10,25,50,100 period time . Results show, because of form of Kharashk basin, it has not ability for making flood, but because of narrowness of basin, runoffs in short time arrive to main drainage and fill it. So it will have ability for making flood where that the river gets out of mountain.