Probabilistic Modeling of Floodwater Level for Dam Reservoirs

A probabilistic method of modeling the floodwater level in a dam reservoir is described the purpose of this paper is to add a probability dimension to hydraulic loading computations. Unlike the standard engineering approach, the method presented here incorporates two innovative aspects. First, the method uses a probabilistic hydrological method (simulated hydrographs for flood probability estimation method) based on simulation techniques, for generating multiple hydrological scenarios. Second, it can address the variability in reservoir level at the time of the occurrence of the flood event. The method generates a random set of floodwater levels from a random selection of flood hydrographs and headwater levels. Statistical analysis of the sample of reservoir levels obtained over a given period allows one to assess a probability distribution for floodwater levels. The method was tested on three applications representing dams having different operating rules and hydromorphological properties. The lessons learned with the present method as compared with the standard engineering approach are discussed from the viewpoint of inclusion in the modeling of the hydraulic loading on the dam and the assessment of the hydraulic safety of the dams.