The Use of Probability-Distributed Initial Losses in Design Flood Estimation

Abstract This paper examines the role played by initial loss modelling in flood estimation for selected Victorian catchments. The large variability of initial loss for different flood events in a catchment is represented by a four-parameter Beta distribution fitted to the observed initial loss data. These stochastic losses are used in a Monte Carlo simulation technique with stochastically generated design rainfall events to determine derived flood frequency curves. It has been found that, in the range of relatively frequent floods, the derived flood frequency curves are quite sensitive to details of the adopted loss modelling approach. The paper shows the potential of adopting stochastic losses in design flood estimation.