Evaluation of the Effective Parameters on Flood Wave Movement through Field Application and Numerical Experiments

Routing is a process used to predict the temporal and spatial variations of a flood hydrograph as it moves through a river reach. The effects of storage and flow resistance within a river reach are reflected by changes in hydrograph shape and timing as the flood wave moves from upstream to downstream. Flood routing procedures may be classified as either hydrological or hydraulics. Hydrological methods use the principle of continuity and a relationship between discharge and temporary storage of excess volumes of water during the flood period. Hydraulic methods of routing involve the numerical solutions of the one dimensional Saint-Venant equations of gradually varied unsteady flow in open channels. In this study, firstly the developed hydraulic models were verified by field observations, secondly the posteriori investigation of channel bed slope, Manning’s roughness coefficient, inflow hydrograph shape factor, time to peak, space step, time step, weighting factor, and the different terms of Saint-Venant equations were studied through the comprehensive numerical experiments. The results indicate that the effects of input parameter errors on the output results are more significant in special situations, such as lower values of Manning’s roughness coefficient and/or a steeper bed slope on the characteristics of a design hydrograph, larger values of the skewness factor and/or time to peak on the channel characteristics, larger values of Manning’s roughness coefficient and/or the bed slope on the space step, and lower values of Manning’s roughness coefficient or a steeper bed slope on the time step and weighting factor.