CRITICAL RAINFALL DURATION FOR MAXIMUM DISCHARGE FROM OVERLAND PLANE

By applying the kinematic wave method to the analysis of overland flow through a rectangular plane, a functional relationship between the critical rainfall duration associated with the maximum peak discharge, and the characteristics of the rainfall intensity-duration curve has been formulated. The traditional approach of equating the critical duration to the time of concentration is valid for planes with low infiltration loss. In this case, the full plane area contributes to the maximum peak discharge. However, for planes with high infiltration loss, the duration of the critical rainfall associated with the maximum peak discharge may be shorter than the time of concentration. Under this condition, only part of the plane contributes to the maximum peak discharge. A method for determining the critical rainfall duration and equations for determining the maximum peak discharge have also been developed.