On the need for non-stationarity in operational estimates of Probable Maximum Precipitation
Abstract
The safety of high-risk water infrastructure, such as large dams, is often assessed by reference to their ability to accommodate floods derived from the Probable Maximum Precipitation (PMP). However, a key shortcoming of traditional PMP estimates is the assumption of a stationary climate, with evidence indicating that key meteorological conditions related to the magnitudes of extreme precipitation, such as atmospheric moisture, are changing in a warming climate. Here we investigate the response of traditional PMP estimates to non-stationarity in atmospheric variables, with emphasis on generalized PMP methods that are used worldwide. With traditional PMP methods, increased seasonal maximum persisting dewpoint temperatures will lead to increased moisture maximization of storms, resulting in higher PMP estimates. Historical trends in observed station data and ERA5 reanalysis data indicate that maximum persisting dewpoint temperatures across Australia have increased over the past 60 years. While future climate model simulations indicate that maximum persisting dewpoints are expected to increase into the future for all modelled Shared Socioeconomic Pathways (SSPs). PMP estimates for large dam locations in Australia are expected to increase between 15% and 38% on average by 2100. Revising the assumption of a stationary PMP, will require regular updating of PMP guidebooks and the incorporation of up to-date data. While the practical implications of potential increases in the PMP will require careful consideration during risk assessments of new and existing high-hazard infrastructure such as dams.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H43C..03V