Estimation height of Runoff Using Curve Number Method and Tools Arc CN-Runoff (Case study: KESHAR Watershed, Tehran)

Due to the global water crisis, having the right information for managing the planning and optimization in different locations is essential. The conventional methods of measuring are very costly, timeconsuming and difficult. In recent years in order to reduce this problem and estimate runoff the watershed, the Geographic Information System (GIS) has been used. In this study, by using daily rainfall data in the SMADA software,return period of 2and 50 years was obtained.ArcCN-Runoff tool with respect to the accuracy and precision in numerous research studies have been made to creat maps and volume of runoff curve number and height were used in the watershed KESHAR. KESHAR area into three groups hydrological B -C-D and was divided into seven land use. The results showed that land use and vegetation and importance of the area in the basin is the most important parameter determines the loss of significant influence and impact on runoff .Curve Number Basin KESHAR shows , rocky outcrops small surface area occupied by the greatest CN (91), The highest volume and highest runoff in the user's area Hydro Group C with 08/56 percent, With low permeability and high potential of runoff is derived, Which puts the area at risk of flooding.