THE OVERLAND FLOW STUDY FOR GODAVARI BASIN

Abstract

The response of a watershed to a storm rainfall event may be conceptually divided into three distinct processes, infiltration into the soil, overland flow and open channel flow. Since each of these processes is dependent upon a variety of natural factors, simulation of the entire process is a difficult task. In this study a kinematic cascade model is used to simulate overland flow in a small watershed. The kinematic cascade model requires simplification of the watershed into a cascade of plane and channel elements in such a way that each element has nearly uniform properties, and their sequence approximately represents the movoment of water over the terrain and ;in the channels. In the present work the Wirpur Nulla watershed in the Godavari Basin has been studied for its response to four rainfall events. The watershed geometry is represented by a cascade of thirteen elements. Infilt-ration losses are computed in accordance with Smith's theory (1972) of soil water flow. The resulting over-J,and and channel flow are simulated by use of the nematic wave theory for gradually varied unsteady flow developed by Liggett,and Woolhiser. The computer program KINGEN 75 compiled by Rovey, et al.(1977) k,vibodies the above computational methods.