Time-varying character of storm intensity frequency and duration curves

Abstract

Recent climate change impact studies suggest that current rainfall intensity-frequency-duration (IFD) curves are likely to change as a result of climate change. In this paper, an effort was made to quantify the changing character of storm IFD curves using data of four consecutive 30-year time slices from 1880 to 2010. The Melbourne Regional Office rainfall data were used for the purposes of the study. Annual maximum series and generalised extreme value distribution were employed to derive the IFD curves using the data of different time slices and the whole period. Results of IFD curves produced from data for the whole period and the current IFD procedure in Australia, described in Australian Rainfall and Runoff (ARR), showed that the former had produced higher intensities for all sub-hourly storms of return periods of 10 to 100 years compared to the latter, and vice versa for return periods below 10 years. For all other storm durations (ie. 1–72 hours) and for short return periods (<10 years), the current ARR method had generated more intense storms. The above results demonstrate that there is a need to conduct further analysis to investigate changing character of storm IFD curves using rainfall data at several stations.