UNCERTAINTY ANALYSIS OF FLASH FLOODS IN NORTH COAST OF EGYPT USING ADJOINT METHODS | ||
| The International Conference on Civil and Architecture Engineering | ||
| Article 42, Volume 9, 9th International Conference on Civil and Architecture Engineering, May 2012, Pages 1-15 PDF (703.07 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/iccae.2012.44367 | ||
| Author | ||
| Hossam M. El Hanafy | ||
| Military technical college, Cairo, Egypt. | ||
| Abstract | ||
| ABSTRACT: The application of adjoint sensitivity analysis to flash flood wave propagation in a river channel has been studied in the research project reported in this paper . The assessment of flood hazard in a coastal watershed is applied using the adjoint sensitivity analysis. The developed numerical model determines the sensitivities of predicted water levels to uncertainties in key controls such as inflow hydrograph, channel topography, frictional resistance and infiltration rate. Sensitivities are calculated using the adjoint equations and are specified in terms of water depths being greater than certain safe threshold depths along the channel. The flood propagation model is based on the St. Venant equations while the propagation of sensitivity information is based on the corresponding adjoint equations. This analysis is achieved using a numerical model that integrates The St. Venant equations forward in time using a staggered finite difference scheme. An enhanced method of characteristics at the downstream boundary provides open boundary conditions and overcomes the problem of reflections from the boundaries. Then, the adjoint model is integrated backwards in time to trace the sensitivity information back through the model domain towards the inflow control boundary. The adjoint model has been verified by means of an identical twin experiment. As a study case, the method is applied to the main stream of a certain watershed at the north coast of Egypt and the location of the specified safe water depths are chosen to be near a culvert beneath the international coastal highway which extends from Egypt to Libya. | ||
| Keywords | ||
| Data assimilation analysis; Open channel flow; Adjoint sensitivity analysis; Numerical models; Flash floods | ||
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