Abstract
The time of concentration for surface runoff is the important factor of the rational formula. The propagation process of overland flow on a sloping plane for unsteady rainfall is investigated using the kinematic wave theory. The relationship between time of concentration and mean rainfall intensity during the time is theoretically revealed. Based on such a relationship, we propose the method of estimating the time of concentration from the observed hyetographs and hydrographs. The proposed method is verified through applying it to several river basins. We can appropriately account for the runoff characteristics of each basin by comparing the estimated time of concentration with the geographical factors of the basin.
