Hossein nezhad - Department of Mechanical Engineering, University of Sistan and Baluchestan, Zahedan, Iran.
Akbari - Department of Civil Engineering, University of Sistan and Baluchestan, Zahedan, Iran Zahedan, Iran

Flooding prediction in large rivers of compound sections is studied. The highly variable unsteady entry of water and sediment to a reach and changes in base level are amongst examples of natural events that induce changes in a river flow-sediment regime. Man-made troubles to nature such as construction of hydraulic structures and the implementation of river training techniques like bank stabilisation, channel realignment, dike construction, and dredging are some examples of artificial causes and problems imposed to river sediment transport regime. Generally a study of movable bed sediment propagation can be approached mathematically from either an analytical or a numerical stand-point. Analytical solutions can be obtained for simplified cases because the three governing equations (continuity and hydrodynamic of flow-sediment transport equations) describing unsteady open channel flow with a movable boundary are first order, nonlinear partial differential equations of the hyperbolic type. Analytical models may be adequate only for an initial rapid evaluation of degradation and aggradation. Most situations, and in particular for highly variable flooding flows however, do not lend themselves to simplified solutions and more complete numerical methods then need to be adopted. In this paper numerical method of characteristics was used for prediction of flow-sediment prediction in large rivers.

Flooding, Characteristics, Large Rivers, Flow-Sediment