Transient Design of Drainage Systems

Abstract

Review of existing transient water table analyses of drainage problems reveals that present techniques permit prediction of water table behavior with sufficient accuracy for the purpose of the practicing engineer. Comparison among solutions and with field data lead to the conclusion that the simplifying Dupuit assumptions are adequate if proper precautions are taken. Prediction equations are presented for water table decay following a single pulse recharge, as well as for water table behavior as a function of arbitrary histograms made by superposition of step input. A method is described and illustrated that uses the water table histogram functions for the development of a probability distribution of water table heights from a long-term precipitation record, a corresponding temperature record, and a knowledge of the drainage system's dimensions and the soil's properties.