Document Type
Journal Article
Publication Title
Journal of Hydrology
Volume
633
Publisher
Elsevier
School
School of Science
Funders
Western Australian Department of Water and Environmental Regulation / Terrestrial Ecosystem Research Network (TERN) / Australian Government
Abstract
The response of groundwater recharge to climate change needs to be understood to enable sustainable management of groundwater systems today and in the future, yet observations of recharge over long-enough time periods to reveal responses to climate trends are scarce. Here we present a meta-analysis of 60 years of recharge studies over the Gnangara Groundwater System of South-West Western Australia, covering a period of sustained drying consistent with climate change projections. The recharge process in the area is defined by a wet winter during which rain saturates a deep, highly permeable soil profile with very low water storage capacity. Measurements of recharge since the 1960s show near-linear reductions in potential recharge of 50%, in response to a 20% reduction in rainfall. For the best-represented land cover in the dataset (Banksia woodland), the reduction in potential recharge was closer to 70%. A simple analytical model suggests that reductions in the duration of winter, coupled with a decreased frequency of winter storms, were most responsible for these declines, and reveals the potential for nonlinear relationships between the recharge fraction (recharge/precipitation) and climatic variables such as mean storm frequency, mean storm depth, and the length of the winter wet season. Overall, results suggest that recharge declines in drying Mediterranean groundwater systems are likely to outstrip the declines in rainfall, and that leveraging existing observation networks worldwide to characterise recharge responses to changing climate is needed to overcome existing interpretation challenges created by inconsistent sites, methods and durations of recharge estimation.
DOI
10.1016/j.jhydrol.2024.131007
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Gelsinari, S., Bourke, S., McCallum, J., McFarelane, D., Hall, J., Silberstein, R., & Thompson, S. (2024). Nonstationary recharge responses to a drying climate in the Gnangara groundwater system, Western Australia. Journal of Hydrology, 633, article 131007. https://doi.org/10.1016/j.jhydrol.2024.131007