Groundwater and water reform
The National Water Initiative requires a number of issues associated with groundwater to be dealt with as key actions. These include:
- improving our knowledge of groundwater-surface water connectivity
- improving the definition of sustainable extraction rates and regimes
- developing better understanding of the relationship between groundwater and important groundwater-dependent ecosystems.
Unless there is a concerted national agenda to deal with current groundwater challenges in a comprehensive and sustained manner, groundwater resources are likely to become over-exploited and potentially put at risk of contamination. This means that flows from groundwater to surface water may decrease or even reverse.
The National Water Commission equally recognises that the sustainable use of groundwater, and its possible augmentation in some instances by managed aquifer recharge, also offers a promising basis for managing water resources as climate gets drier and hotter, and evaporation further affects surface water storage.
The National Water Initiative recognises the connectivity between surface and groundwater resources and requires connected systems to be managed as a single resource.
With the increased use of groundwater across the country and the long-running drought decreasing surface water availability, the need to better manage groundwater and connected resources has become paramount. Improved understanding of groundwater and management of groundwater-surface water interactions is fundamental to this.
Baseline groundwater information
The Australian Water Resources 2005 baseline study identified aquifers throughout the country where water entitlements and/or use exceeded sustainable yield or recharge.
The study reported on groundwater stocks for its 51 selected catchments. It was estimated that in 2004-05 there was approximately 49,200 GL of groundwater recharge nationally. This was 17% of total runoff and recharge. However, of the nation's total water use, groundwater extractions comprised over 30% in 2004-05.
Measuring progress
In its 2007 Biennial Assessment of progress against the National Water Initiative, the National Water Commission expressed considerable concern about the management of groundwater throughout Australia. (See also 2009 Biennial Assessment)
The assessment identified the over-allocation of water resources, limited recognition of groundwater and lack of a harmonised national approach for monitoring groundwater as areas requiring urgent additional work. The failure to address this issue is having a serious effect on the security of supply to surface water consumptive users, to surface water environmental flows and groundwater-dependent ecosystems.
Just as the science underpinning our knowledge is less developed than for surface systems, so are current management arrangements. While significant progress has been made in systems to allow trading of surface water entitlements and allocations, similar systems for groundwater are largely absent.
The Commission believes that there are considerable benefits in moving to the integrated management of connected ground and surface water systems, arising from the large storage capacities and dramatically lower evaporative losses of many groundwater aquifers. This would entail:
- widespread introduction of volumetric entitlements to groundwater use and an allocation system
- trading entitlements and allocations from surface to groundwater, groundwater to groundwater, or ground to surface water
- countercyclical allocation and/or trading regimes, where groundwater use could be increased in years of low surface allocations and subsequently reduced in other years.