2-D NUMERICAL MODEL FOR FLOOD FORECAST IN RIVERS WITH HEAVILY SEDIMENT LADEN FLOW

I.INTRODUCTIONTwo-dimensionalnumericalmodelisaPOwerfoltoolforengineersandriVermanagerstopredictfloodhydxaulics,identifyareasofinundation,anddesignoptionsforfloodcontrollingstructures.SomespecialproblemswithheavilysedimentladenflowriVershouldbecarefullyconsideredforthenumericalmodeldesigning;1.theplaneformofariVerisusuallybraidedanditsmainchannelshiftsoften.Themainchannelandbarreplaceeachotherseveraltimesinonefloodevent.Atagivenlocationthewaterdepthmaychangefromover10meterstoseveralcenhm…

2-D NUMERICAL MODEL FOR FLOOD FORECAST IN RIVERS WITH HEAVILY SEDIMENT LADEN FLOW

For heavily sediment laden flow the flood disaster is markedly affected by fluvial process. The flood propagating process in the Lower Yellow River is such a typical case. This paper presents a depth-integrated two-dimensional numerical model which can be used to simulate the flood migration in a river with heavily sediment laden flow. A net node method is employed to solve the water flow and sediment transport continuum equations. Experimental results on the non-Newtonian properties of heavily sediment laden flow are introduced into present model and thus, some special phenomena associated with high sediment concentration in natural river can be simulated. A density variation is introduced into water continuity equation and thus the effect of the sediment erosion and deposition on the mass conservation during flood process can be considered. A four points FRAM scheme is used to solve momentum equation. Non-equilibrium sediment transport mechanism is employed to simulate the two dimensional sediment transport process. Based on some field-observed data in a flood diverting process in the Lower Yellow River, a series of special problems for the application of a two-dimensional numerical model on the predictions of the degradation and aggradation during the flood processes are discussed.