Sustainable management of coastal groundwater resources

Background

Coastal dune aquifers are an important source of water for many communities along the NSW coast, and support diverse groundwater-dependent ecosystems (GDEs). However, in recent decades there has been increasing pressure on the sustainability of coastal groundwater resources due to factors such as growing urbanisation and seasonal tourism. This has made the long-term sustainable management of existing groundwater supplies an important issue for many coastal communities and councils.

The Sustainable Management of Coastal Groundwater Resources project investigated groundwater systems and processes that occur in coastal dune aquifers on the mid-north coast of NSW, between Crescent Head and South West Rocks. The Australian Government through the National Water Commission’s Raising National Water Standards Program funded this research project. The project team included Geoscience Australia working in collaboration with the Kempsey Shire Council, GHD, NSW Department of Primary Industries (Office of Water), Arche Consulting and Ecoseal Developments.

Deliverables

This project has delivered:

• a comprehensive monitoring dataset on groundwater levels and water quality to enable robust analysis of coastal dune aquifers in northern NSW
• integration of water quantity and quality considerations with a risk management framework to evaluate sustainable extraction regimes for coastal groundwater systems
• improved understanding of sustainable extraction regimes for the Macleay Coastal Sands Aquifer, and improved assessment of impacts on coastal GDEs
• improved management of aquifers for long-term sustainable use, providing pathways for minimising aquifer stress, and improved assessment of new opportunities for sustainable coastal groundwater development
• trade-offs between consumptive groundwater use and the requirements of dependent ecosystems in coastal regions by combining seawater intrusion models and applying indicators and socio-economic analysis.

Outcomes

The key outcome of this project was the development of an integrated approach for managing the availability and quality of coastal groundwater resources. This approach focused on long-term sustainable management to ensure that coastal aquifers do not become over-allocated, depleted or degraded as a consequence of increasing demand from growing coastal communities.

The success of this project has been achieved by combining groundwater and seawater intrusion modelling tools, the assessment of GDEs, and a framework for applying indicators and cost–benefit analyses to support the management of coastal sand aquifers. The management approaches developed for this project can also be applied to similar coastal sand dune aquifers along other parts of the NSW coastline. This will help ensure that any new coastal groundwater sources are developed sustainably, with minimal impact on GDEs such as dune vegetation communities.

Outputs

The key findings of this project were published as National Water Commission Waterlines report #79 in 2012: Sustainable management of coastal groundwater resources and opportunities for further development: executive summary.

This summary report provides an overview of the project and outlines the five main research components:

• Hydrogeology, monitoring and hydrochemistry
• Development of a flow and transport model for the Macleay Sands Aquifer
• Mapping of groundwater-dependent ecosystems
• The development and application of early warning indicators to assess the condition of groundwater resources
• Socio-economic scoping report.

The Waterlines report is supported by five separate technical reports from the Sustainable Management of Coastal Groundwater Resources project:

• Hydrogeology, Monitoring and Hydrochemistry for the Macleay Sands Aquifer
• Development of a Flow & Transport Model for the Macleay Sands Aquifer.
• Final Groundwater Dependent Ecosystems Report
• The Development and Application of Indicators to Assess the Condition of Groundwater Resources - A New Approach for Groundwater Management
• Socio Economics Scoping Report.