Capability of Various Statistical Analyses in Estimation of Unit Hydrograph Components for Northern Watersheds of Iran

The present research aimed to compare different methods of statistical analysis and to select the best method for achievement to the model among components of synthetic unit hydrograph by using of the physical characteristics of catchments, in northern catchments of Iran, with the area of 177000 km2 in Giulan, Mazandaran and Golestan Provinces. For execution of the research, 9 physical characteristics of catchment and 8 characteristics of unit hydrograph components for 44 storms in the north parts of Iran have been chosen. Regression test by using bivariate approach and various forms such as linear, logarithmic, inverse, quadratic, cubic, exponential, power and combined forms has been used after execution of factorial analysis. The obtained models were evaluated by relative errors, RMSE and efficiency coefficient. Results showed that the bivariate models have more accuracy in estimation of the amounts especially in the case of temporal variables (base time, time to peak, time to depletion). Regression of several variables has high accuracy in estimation of discharge and recursion regression of several variables has the highest accuracy.