Critical Appraisal of Various Approaches to Predict Flow in Compound Channel Having Converging and Diverging Floodplains

Abstract

Each river in the world is idiosyncratic in its geometry. Some are gently curve, others meander, and some others are relatively straight, converging, diverging or skewed. But at the time of flood they forget their boundaries and inundate their surroundings. The size of river geometry changes from section to section longitudinally due to different hydraulic and surface conditions called non-prismatic compound channel. Non-prismatic compound channel generally categorizes into three types-converging, diverging and skewed. There are various methods exist which are generally meant for prismatic compound channel cases but very few methods exist for non-prismatic cases. There has also been significant progress of work in meandering channels. But an area which has been somewhat neglected is that of non-prismatic compound channels. As discharge prediction is a vital issue in flood risk management and more important for a river in changed geometry. Therefore, a critical appraisal of the various techniques developed by various researchers across the globe for the past few decades to predict the stage-discharge relationship of a non-prismatic compound channel has been performed. The most widely used methods for non-prismatic compound channels are Modified Lateral Distribution method (MLDM), Ex-tended lateral distribution method (Ex-LDM), and Exchange Discharge model (EDM) and Independent Subsection method (ISM). The advantages and disadvantages of all the aforementioned have been discussed in this paper. The most suitable method for different flow conditions has been proposed as it will facilitate the researchers to focus on the area of river hydraulics and that may lead to solve other related objectives.