Warmer temperatures are expected to increase extreme short-duration rainfall due to the increased moisture-
holding capacity of the atmosphere. While attention has been paid to the impacts of climate change on future
design rainfalls at daily or longer time scales, the potential changes in short duration design rainfalls have been
often overlooked due to the limited availability of sub-daily projections and observations. This study uses a high-
resolution regional climate model (RCM) to predict the changes in sub-daily design rainfalls for the Greater
Sydney region in Australia. Sixteen methods for predicting changes to sub-daily future extremes are assessed
based on different options for bias correction, disaggregation and frequency analysis. A Monte Carlo cross-
validation procedure is employed to evaluate the skill of each method in estimating the design rainfall for the
current climate. It is found that bias correction significantly improves the accuracy of the design rainfall estimated for the current climate. For 1 h events, bias correcting the hourly annual maximum rainfall simulated by
the RCM produces design rainfall closest to observations, whereas for multi-hour events, disaggregating the daily
rainfall total is recommended. This suggests that the RCM fails to simulate the observed multi-duration rainfall
persistence, which is a common issue for most climate models. Despite the significant differences in the estimated design rainfalls between different methods, all methods lead to an increase in design rainfalls across the
majority of the study region.
Fig. 9. The percentage change in 1 h design rainfall depth estimated from WRF/MK3.5 simulations for 1 in 5 year events using different methods.
This page is maintained by Jason Evans |
Last updated 23 January 2018