Evaluating Rainfall Loss and Estimating Runoff Hydrograph and Peak Discharge

Fundamental studies on drainage planning for reclaimed lands (IV)

Abstract

Discharge just before a rainfall event, antecedent precipitation evapotranspiration index, and result of cylinder intake rate test are developed to evaluate rainfall loss in a kinematic wave model. Infiltration parameters obtained from such methods and the experimentally based roughness coefficients were taken into the prediction model, and runoff analyses of three experimental catchments were made respectively. The results obtained were as follows. The experimentally based roughness coefficients can give good prediction of the runoff characteristic of the actual catchment area. The good predictions in the peak discharge show that, the methods of estimating sorptivity with antecedent precipitation evapotranspiration and/or the result of cylinder intake rate test are useful for the prediction of runoff discharge. One of the reasons for taking the final infiltration rate between 1/3-2/3 of saturated hydraulic conductivity, can be explained by the relationship between the rainfall pattern and the sampling interval of rainfall data.