The unspoken link between flooding and global warming – will future storms and floods intensify?

Thursday, 18 December 2014
Conrad Wasko, University of New South Wales, Sydney, NSW, Australia and Ashish Sharma, University of New South Wales, School of Civil and Environmental Engineering, Sydney, NSW, Australia
With higher temperatures increasing extreme rainfall intensities are predicted. However, as rainfall is highly variable spatially and temporally trends in historical records are often difficult to identify. Instead studies focus on developing statistical relationships between meteorological variables which have an underlying physical relationship. For example, studies have exploited the Clausius-Clapeyron relationship by linking rainfall intensity to temperature. This relationship is then used to predict extreme rainfall intensities for a future warmer climate.

Using sub-daily and daily rainfall data throughout Australia (which represents good spatial and temporal coverage across all dominant climatic zones in the world) we extend this logic to spatial and temporal attributes of rainfall. By separating the change in storm shape, both temporally and spatially, from the change in storm volume, we find that storms are intensifying with increasing temperatures. As a result, consistent changes are being noticed in their temporal and spatial patterns, required inputs for design flood estimation. It is also shown that for a warmer climate, storms are likely to have characteristics which result in floods with shorter durations and greater flood peaks.