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 is presented. 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 in the meandering river channel, left over bank flood plain, and right over bank flood plain were all identified separately. Thus, the differences in hydraulic and geometric properties and flow-path distances were considered for all three divisions of the valley cross-section. This development differs from conventional one-dimensional treatment of unsteady flows in rivers with flood plain wherein the flow is either averaged across the total cross-sectional area (channel and flood plain) or the flood plain is treated as off-channel storage, and the reach lengths of the channel and flood plain are assumed to be identical. The weighted four-point implicit finite difference method is selected to solve a modified Sain-Venant equations for its versatility and computing efficiency. The numerical model was applied to the Euphrates river at the reach between Haditha dam and Hit city along (124.4 km) to make a sensitivity analysis of the following parameters: maximum flood wave discharge, maximum flood wave elevation, lag time of the peak discharge, lag time of the peak level, and time of arrival of flood wave to a seven major cities along the Euphrates river in a case study and comparing it with a same parameters produced when a conventional one-dimensional treatment of unsteady flows in river with flood plains where the meandering in river is neglected.