Water Surface Profile Computation in Nonprismatic Compound Channels

Abstract

A river generally exhibits a two stage geometry i.e. deeper main channel and shallow floodplain called compound section. In most of the compound channels, the floodplain geometry is found to be varying along the length of the flow called non-prismatic compound channel. The modelling of such flows is of primary importance when seeking to identify flooded areas and for flood risk management studies etc. The water surface profile is a series of transition curve from the normal depth line in one sub reach to the normal depth line in the adjacent sub reach. Water surface modeling help for the study of flood waves, water level calculation during flood, stage discharge relation, design of water work structures. All non-prismatic open channel flows are found to be unsteady and non-uniform. So these flows are difficult to analyse. In this paper experiments have been conducted to compute the water surface profile of non-prismatic compound channel for different converging angle and an attempt has been made to formulate mathematical models for predicting water surface profile by using the new experimental data of N.I.T, Rourkela and other standard data sets for different converging compound channels.