Application of System Reliability Analysis to Flood Forecasting

The decision making process regarding the issuance of flood watches and warnings often relies on the use of real-time flood forecasting models for watersheds. The floods predicted by these models are subject to uncertainties which may be significant for efficient operation of flood warning and preparedness systems. System reliability analysis offers a means to account for the uncertainties in the flood forecast in the form of occurrence probabilities for any flood level of interest. In this paper the advanced first-order second moment (AFOSM) reliability analysis method is used to analyze the uncertainties in a rainfall-runoff flood frequency model proposed by Eagleson (1972) and extended by Wood (1976) for an analytical derivation of the expected flood exceedance probability considering parameter uncertainty. Comparison of the results shows that the AFOSM method is a viable, reasonable, and practical method useful for hydrologic problems subject to uncertainties.