RUNOFF HYDROGRAPH and it is given as:\(t = 0.0194{L^{0.77}}{S^{ - 0.385}}\)Where,t = time of concentration in minutesL = the maximum length of water travel in m.S = the slope of the catchment and it is given as\(S = \frac{{{\rm{\Delta }}H}}{L}\)ΔH is the difference in elevation between most remote points on the catchment outlet.Note:Time of Concentration is the time required by the entire drainage area to contribute to the runoff is CALLED time of concentration or time required by the most extreme point in the drainage to reach the point of interest.