DETERMINING OF REGIONAL COEFFICIENTS OF FULLER'S EMPIRICAL FORMULA TO ESTIMATE MAXIMUM INSTANTANEOUS DISCHARGES IN DASHT KAVIR BASIN, KALSHOUR SABZEVAR, IRAN

Estimation of the magnitude and frequency of maximum instantaneous discharges and hydrographs are used for a variety of purposes, such as the design of bridges, culverts, flood-control structures; and the management and regulation of floodplains. Fuller (1914), developed a flood-frequency formula based on analysis of flood peaks in hundred of streams to provide simple methods of estimating maximum instantaneous discharges, and sought to link maximum instantaneous discharges having various average return periods to the mean of the maximum annual discharges with a factor calibrated for different catchments. The aim of this study is the evaluation of the mentioned method in order to estimate maximum instantaneous discharge and calibrating its considered coefficients in Kaal Shour Sabzevar region. Therefore, the collected data from 10 hydrometric stations in the region were used in analysis and regional coefficient was obtained 0.041 and regional inundation coefficient is from 0.88 to 2.23 in 5 to 200-year return periods. The results showed that the discharge calculated by Fuller’s empirical formula is less than values calculated by statistical distributions.