Climate change impact on groundwater resources in Australia
Waterlines report No 67 - December 2011
This is the final in a series of reports from a national project investigating the impact of climate change on groundwater resources.
Over the past 80 years Australian climatic trends have indicated warming over most of Australia (except in the inland north-west), increasing rainfall over northern, central and north-west Australia, and decreasing rainfall in eastern, south-east and south-west Australia. This report summarises the results of extensive modelling and explores the implications of how climate change may affect groundwater recharge and discharge processes.
The projected future climates were inferred from 16 global climate models (GCMs) of the Intergovernmental Panel on Climate Change 4th Assessment Report. The full range of future climate projections was accounted for by scaling these 16 GCM results according to three global warming scenarios (low, medium and high) for both 2030 and 2050. The project also developed an aquifer characterisation tool to assess which groundwater systems are likely to be sensitive to climate change, and of those, which are nationally important (using economic, social and environmental criteria).
Key findings outlined in the report include:
- Various climate models yield different results from similar initial scenarios – however, projections are consistent for south-west Western Australia and the southern Murray–Darling Basin, where all global climate models project a decrease in rainfall.
- Not all groundwater systems are equally sensitive to climate change.
- Of the 14 aquifers identified as both sensitive and important, 11 are dependent on groundwater (that is, groundwater comprises greater than 60 per cent of all water extraction).
- Diffuse recharge is likely to become more variable. At best, current practice cannot fully account for variability, and this is likely to be exacerbated. This will affect our ability (and confidence) in water balance estimates that underpin water plans.
- Groundwater/surface water interactions with rivers are highly sensitive to climate change and could have a profound effect on water availability. This applies equally to wetter as well as drier future climates.
- Current knowledge of groundwater systems (both monitoring data and conceptualisation) is inadequate to allow informed climate change adaptation and management decisions in most of Australia. Models currently in use for management should undergo an audit to establish if they are fit for purpose for proposing climate change adaption strategies.
- Adaption to climate change is predicted to incur significant costs for groundwater users and managers.
The project built on work already carried out by CSIRO in the Murray–Darling Basin, northern Australia, south-west Western Australia and Tasmania.
Documents for download
Climate change impact on groundwater resources in Australia (PDF 7.6MB)
Climate change impact on groundwater resources in Australia (DOC 19.6MB)