Comparison of some empirical methods for evaluation of the Time ofConcentration (TC) inMaime basin of Ilam province

Time parameters are used in the majority of hydraulic and hydrologic models. The most popular time parameter in hydrology is Time of Concentration (TC). TC is the time that water needs to reach to outlet from the furthest point of basin. TC is used in the design of weirs, flood volume evaluation, flood hydrograph and many other hydrological analyses. There are a lot of methods for TC evaluation and this research tries to select the best method of TC evaluation in Maime basin. For evaluation of real TC, field method was applied using a salt solution for measurement of Travel Time, after that the result of it was compared with the results of empirical formula it was confirmed that Kirpich, Chow and Rational Hydrograph methods had the least discrepancy, therefore they are acceptable.