Authors

Cheng-Lung Chen

Document Type

Report

Publication Date

January 1975

Abstract

The main objective of this study is to develop an accurate design method for computing inlet hydrographs of surface runoff, with average recurrence intervals of 10, 25, and 50 years, from typical urban highway by flood routing technique. The boundary-value problem of one-dimensional infiltration resulting from rainfall is formulated and solved numerically on a digital computer. The numerical solutions of this idealized mathematical model is used as a basic testing tool in the subsequent analysis of various parametric infiltration models including the Green-Ampt, Kostiakov, Philip, Horton, and Holtan equations. The time of ponding is shown to be the most important parameter in a parametric infiltration model and can be expressed in terms of other parameters in the model as well as the rainfall intensity. The values of all the model parameters in the model as well as the rainfall intensity. The values of all the model parameters are determined to be fairly constant for a soil having the same initial and upper boundary (soil surface) conditions. Use of the Green-Ampt, Kostiakov, and Philip type models for the prediction of the infiltration rate before and after ponding is proved to be satisfactory. For engineering practice, the standard infiltration-capacity curves for soil-cover-moisture complexes representing urban highway sideslopes are empirically developed based on the unique selection of the Soil Conservation Service runoff curve number. Validity of typical standard curves so developed were experimentally examined in the Utah Water Research Laboratory stormflow experiment facility.

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