Issue Paper 2
National Groundwater Committee
Department of the Environment and Heritage, 2004
About the issue paper
There is increasing recognition of the partial or total dependence of certain ecosystems on groundwater, and that past management arrangements have made inadequate provisions for the supply of water to maintain priority ecosystems.
COAG water reforms require that environmental water requirements need to be taken into account when assessing the sustainability of water resource development.
Ecosystems dependent or partially dependent on groundwater would include:
- Ecosystems based on vegetation that draws directly on groundwater;
- Ecosystems with some dependence on base flow to streams;
- Aquifer and cave ecosystems;
- Groundwater dependent wetlands; and
- Estuarine and marine ecosystems where there is a substantial groundwater input.
Although there has been significant progress in identifying potential dependence at state level, there is still considerable difficulty in quantitatively defining the level and importance of dependence. "Dependence" is generally considered to be proportional to the fraction of the annual water budget made up by groundwater.
The major challenge for management of groundwater dependent ecosystems is in providing quantitative criteria on which to base protection of priority ecosystems. In this respect, there is little knowledge of indicators of ecosystem stress that would allow adaptive management of groundwater to protect priority systems and no guidance on what impacts are acceptable, although this would depend on the perceived value of the ecosystem. Indeed, there are no accepted ways of valuing ecosystems, and no obvious way of determining costs of loss of ecosystem function.
There is a general consensus that in Australia there is a need for a national (generic) approach or at least coordination of approaches, to define methodology and critical factors and processes which are needed to develop a better understanding of groundwater-dependent ecosystems and of how to manage these better. It is recognised that within the Australian federation, there is a commonality of objectives towards this end, but a diversity of approaches. Any generic approach should examine this diversity and learn from it.