Optimization the regional coefficients of Fuller's empirical formula with Non-Linear Programming method to estimate maximum instantaneous discharges.

There are several statistical and empirical methods for flood discharge estimation. One of the empirical methods that were considered in this study was fuller equation. The advantage of fuller equation in compression of other empirical methods is estimation of different periods of flood discharge. In the first step، hydrological missing data generated using. In order to continue to use empirical formula for estimating Fuller maximum instantaneous flow rate in different areas، users should calibrate coefficients of equation for each region. In this study، coefficients of fuller formula optimized using non-linear programming model by Lingo. The maximum instantaneous flow rate for the region was estimated to selected stations. The results show that، the regional coefficient (c) is 0. 19 and (ß) coefficient for return periods of 2، 5، 10، 25، 50، 100، 200 years are 0، 0. 93، 1. 16، 1. 38، 1. 53، 1. 68، 1. 84 respectively. Therefore، Fuller formula coefficients (2. 66 and -0. 3) was calibrated in significant level 0. 01 and correlation coefficient (R= 0. 95) for the study area. The results shows that the optimized fuller formula could have better fitting in the lower return period (2، 3، 5، 25 Yr)