Development of Hydrograph using Different Rainfall Components in Kasilian Watershed

Various limitations, including the insufficient number of hydrometric stations, difficulty in collecting hydrometric data and high cost of data and information collection, requires using hydrologic models to estimate flood hydrographs. Application of rainfall data in un-gauged areas is a feasible option owing to their acceptable accuracy. This research is aimed at examining the possibility of integrating characteristics of hyetographs and hydrographs in order to develop the flood hydrograph and recognize its characteristics in Kasilian region with an area of 66.75 sq km, based on the available rainfall data. For this purpose, 15 characteristics of the hyetograph, 11 characteristics of the hydrograph and 11 characteristics of a time index connecting hyetograph and hydrograph for 49 storms were considered. The relationships were investigated using bivariate and multivariate regressions. Results showed hydrographs may be produced based on components of hyetographs, and as well developing simplest form of hydrographs only by the duration of excess rainfall. An almost perfect hydrograph can be produced by calculating the duration and amount of excess rainfall and occurrence time of 15 minutes maximum intensity