Numerical Modeling of Flood Wave Behavior with Meandering Effects (Euphrates River, Haditha-Hit)

Abstract

A numerical model for routing of flood wave in a part of meandering river ispresented. It is based on a modified form of the complete one-dimensional Saint-Venant equations of unsteady flow. These equations were modified such that flows inthe meandering river channel, left over bank flood plain, and right over bank floodplain were all identified separately. Thus, the differences in hydraulic and geometricproperties and flow-path distances were considered for all three divisions of the valleycross-section. This development differs from conventional one-dimensional treatmentof unsteady flows in rivers with flood plain wherein the flow is either averaged acrossthe total cross-sectional area (channel and flood plain) or the flood plain is treated asoff-channel storage, and the reach lengths of the channel and flood plain are assumedto be identical. The weighted four-point implicit finite difference method is selected tosolve a modified Sain-Venant equations for its versatility and computing efficiency.The numerical model was applied to the Euphrates river at the reach between Hadithadam and Hit city along (124.4 km) to make a sensitivity analysis of the followingparameters: maximum flood wave discharge, maximum flood wave elevation, lag timeof the peak discharge, lag time of the peak level, and time of arrival of flood wave to aseven major cities along the Euphrates river in a case study and comparing it with asame parameters produced when a conventional one-dimensional treatment ofunsteady flows in river with flood plains where the meandering in river is neglected.