Estimation of Effective Rainfall Guidance Considering Infiltration Capacity-Rainfall Intensity

Abstract

This study investigated the effect of the lag time on the concentration time and the change in effective rainfall depending on the infiltration capacity and rainfall intensity by the status of land use to research the relevance of infiltration capacity-rainfall intensity and the effective rainfall by land categories according to the characteristics of the drainage basin. As a result of analysis, deviation in the lag time is significantly occurring from two hours to nineteen hours and fifty-five minutes depending on the rainfall intensity and the form of the flood hydrograph rising limb is being determined by this. It has been analyzed that the forest land is divided into the region where runoff does not occur even with the rainfall of more than 500 mm/hr and the region where runoff occurs 100% with the rainfall of more than 80 mm/hr and there is an upland field area where runoff does not occur even with the rainfall of more than 120 mm/hr and the area where runoff occurs 100% if the rainfall of more than 20 mm/hr occurs while runoff may occur 100% in the land and rice paddy with the rainfall of 20 mm/hr. As the infiltration capacity varies according to the soil series and status of land use, the objective application of the runoff coefficient of rational method and runoff curve number is needed.