Groundwater responses to the 2010–11 floods
High rainfall and significant flooding associated with a recognised La Niña weather pattern occurred in many areas of Australia during late 2010 and early 2011. Groundwater responses to the 2010–11 floods attempts to assess the impacts of those events on groundwater recharge for selected aquifers across Australia, and provides an insight into an aspect of the hydrological cycle that is critical to the water balance but can be very difficult to measure.
The report illustrates the groundwater level responses that occurred in selected regions of Australia during and following the floods, and identifies key links between those responses and aspects of the local and regional aquifer systems.
This assessment considered rainfall, streamflow and groundwater levels over the short term (12 months), the medium term (the ‘Millennium drought’), and the long term (since monitoring commenced) in selected areas across Australia, including:
- Lockyer Valley (Queensland)
- Murrumbidgee Valley (New South Wales)
- Loddon Valley (Victoria)
- Cam and Emu valleys (Tasmania)
- Gascoyne Valley (Western Australia)
The report demonstrates that groundwater levels, which had fallen during preceding seasons (and in some cases over the duration of the Millennium drought), rose in all examined areas following the floods. However, groundwater levels only recovered to pre-drought levels in some aquifers.
The relatively smaller aquifers that were assessed appear to have been fully recharged by the recent heavy rains and flooding. In contrast, the relatively larger, regional aquifers still appear to be affected by both drought and high levels of groundwater extraction, and will require much more than one year of heavy rain and flooding events to fully recharge.
The report
This study is an example of targeted investment by the Commission under the Raising National Water Standards Program to improve the understanding of groundwater resources across Australia.