Developing a model for analysis of uncertainties in prediction of floods

ABSTRACT

A realistic new sediment-laden water prediction computer model was developed. In this model unsteady non-uniform flow computations were incorporated. Using this model, flooding flow-sediments were simulated and compared to earlier research including hydrologic engineering centre [HEC-series] computer models. Uncertain value of parameters and errors in flow-sediment transport equation in existing coupled flow-sediment models were studied. Sensitive nonlinear flow-sediment terms simplified in linear models and state of non-uniform sediment laden flooding flows in loosed boundaries were considered. The new applied modeling of flooding sediment-water transport simulation was tested with data of three rivers and relative merits of the various techniques involved in full phases of flow-sediment in loosed boundaries for real river situations were discussed. Uncertain values of sensitive parameters were investigated through sensitivity analysis of flow-sediment parameters in three hydrologic catchments. Results of numerical analysis were compared to field observations relying on the accuracy of the developed model. Uncertainties and errors involved in; numerical scheme, hydraulic-sediment parameters, the out-reach output, flooding sediment-laden water characteristics, peak outflow, time increments, depth, speed of floods were found rather sensitive to the solution of problems. Computed grid size intervals and the peak outflows increased with space step and decreased with time step. Errors of in-reach parameters, the peak inflow hydrograph and roughness coefficient highlighted out-reach output