-

Considering the lack of hydrometrical stations in most small watersheds, determination of maximum flood discharge requires a suitable method to estimate runoff and peak flow that's used in flood and erosion control management plans. One of such methods is the graphical method presented by Natural Resources Conservation Service of the United States Department of Agriculture. To evaluate the applicability of this method, 19 watersheds in three regions of Iran Vis Karaj-Ghazvin region (region 1), Shomal region (region 2) and Azarbaiejan region (region 3) were selected. Among the different types of rain, type II exhibits a minimum error. The results showed this method had better applicability for estimation of peak flood in Karaj-Ghazvin and Azarbaiejan regions, but was more erroneous in Shomal region.