Flood potential zonation in Sarab of Darrehshahr Drainage Basin Using Curve Number Method

The one of the natural hazards is Flood that affects almost all of the country and brings financial and human damages; therefore recognition of the areas with flooding potential is one of the most important measures to decreasing these damages. In this research Darrehshahr drainage basin has been analyzed in view of flooding potential and identifying efficient factors in flooding potential. The run-off has been estimated by using curve number method (CN) of American Soil Conservation Service (SCS).For this purpose, in the beginning the needed data and information including land use and hydrologic groups of basin soil maps were gathered and inputted to GIS system. The CN and the infiltration maps were prepared by using of SCS method and compilation the data and information, then were calculated the run-off volume (Q) for basin using of SCS formula and maximum 24 hours precipitation of basin. Finally, the basin study were divided into 4 classes in view of flooding potential according to first quarter, median and third quarter of values of the run-off volume that 9.1 km2 of it included the very high flood potential, 7.8 km2 of it high potential,13 km2 of it average potential and 6.6 km2 of it had also low potential.