COMPARISONS OF WEIBULL-BASED AND EXPONENTIAL-BASED PARTIAL DURATION STOCHASTIC FLOOD MODELS

A stochastic flood model with a Weibull distribution for flood exceeda nces is examined and compared to the traditional exponential-based mod el in terms of predictive and descriptive properties. The model is bas ed upon the traditional representation of the flood mechanism as a Poi sson counting process. It is expected that the more flexible Weibull d istribution will be capable of modeling flood series which exhibit a w ider range of variability than the exponential model. The Weibull-base d model is shown to possess predictive properties which are superior t o the exponential model when samples exhibit coefficients of variation less than 1.5 and sample sizes are on the order of 2 events per year. These characteristics are shown to exist in many observed flood serie s in the Gulf Coast of the United States.