Simulation Flood Hydrograph of Atashgah Basin River of Ardabil Provice using optimized Rainfall Pattern

In the present study, seven temporal rainfall distribution patterns (i.e. SCS, WMO, Huff 1st, Huff 2nd, Huff 3rd, Huff 4th, and regional) were evaluated in order to simulate maximum flood flow using SCS, CLARK, and SNYDER, runoff rainfall models in Atashgah basin of Ardebil Province. The aim of this study is simulation of flood hydrograph using watershed modeling system and selection suitable rainfall pattern of study area. Daily maximum rainfall map was obtained by Kriging and Cokriging interpolation models using circular, globular, exponential, gaussian, and normal fitting models as well as reversed Weighted distance, function-radius-axis, general estimator, and local estimator methods. Universal cokriging model with normal method was selected as the best model. Temporal 6-h rainfall distribution pattern was obtained from 7 rainfall events with durations of 4.5-6.5 hours. The average of curve number was calculated to be 76.5 for the study area. the results obtained from the present study showed that Huff 4th rainfall pattern with the maximum rainfall in the 4th quarter simulat the highest flow. The simulated flow with different patterns indicated that in SCS model, WMO rainfall and in SNYDER and CLARK models, Huff 2nd pattern had the most realistic results compared to observed flow. SCS rainfall-runoff model using WMO rainfall pattern with minimum RE and RMSE equal to 7% and 1.57 m3/s respectively was selected as the best model for Atashgah basin.