Growth curves and temporal patterns of short duration design storms for extreme events

There are many important dams and other structures on catchments smaller than 1000 km2 with flood response times less than 24 hours, however these catchments have been largely overlooked in previous research into large and extreme floods. This paper is an initial step in “catching up” design practice for short duration rainfall events to the current best practice available for estimation of floods from rainfall events with durations of 24 hours and greater. Three issues are specifically addressed. A regional analysis of short duration rainfall depths is conducted to extend the frequency curve beyond an AEP of 1 in 100. Rainfall frequency curves are estimated for durations between 0.5 and 12 hours, using data from ten pluviograph sites around Australia. Sets of temporal patterns are derived that could be useful in joint probability analysis of short duration rainfall events. Temporal patterns for rainfall antecedent to large rainfall events were also extracted from the analysis. The effects of these new rainfall depths and temporal patterns on flood frequency curves are tested by applying them to a rainfall-runoff routing model for a small catchment in Southern Australia.