A systematic evaluation of time of concentration models in a predominantly agrarian catchment of Southeastern Nigeria

In order to accurately estimate peak discharge and subsequently determine the size of hydraulic structures, the time of concentration (TC) of the catchment must be accurately determined. This study was aimed at comparing the applicability of 15 carefully selected TC equations to Ifite Ogwari catchment in Anambra State, Nigeria. The calculated values of TC were subjected to exploratory statistical analysis and sensitivity analysis. The Temez, Haktanir and Sezen and Chow equations gave the most representative values of TC of the sub-catchments with 100% of all TC values falling within the inclusion criteria of median ± 0.5 SD while returning the median TC three times each out of eleven catchments. The Pasini and Sheridan models were the worst performing with all the TC values calculated falling outside median ± 0.5 SD and median ± SD. Sensitivity analyses indicate that 82% of the equations considered the longest flow path as the most important parameter.