Author(s): Tawatchai Tingsanchali; Narendra Kumar Lal

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Abstract: Those semi-empirical exponential equations which can describe subsidence of flood peak discharges in channels during overbank flow periods are developed by using dimensional analysis to analyze the numerical results computed from various flood routing techniques based on unsteady free surface flow equations. The subsidence is expressed as a function of eight dimensionless parameters related to the geometry and Manning roughness coefficients of main channel and overbank sections, bed slopes, duration of flood wave, rising time and recession time of overbank flow hydrograph. Two different shapes of inflow flood hydrographs are considered. The derived equations are tested by applying them to calculate the subsidence of flood peak discharges in the Nam Pong and Chao Phraya Rivers in Thailand. The results are found to be very good. Sensitivity analysis shows that the method is not sensitive to error of + 20% in input data. Backwater effects may be included with some modifications.

DOI: https://doi.org/10.1080/00221688809499195

Year: 1988