The Albany Groundwater Area covers an area of 2015 km2 and is an important urban and agricultural development area on the south coast of Western Australia. It is facing severe climate effects with a 40-year drying trend projected to continue. Groundwater supplies over 80 per cent of drinking water to Albany and surrounding towns. As alternative drinking water supplies in the region are scarce, careful management of this limited groundwater resource is essential.
The Department of Water has recently completed an investigation into the Albany Groundwater Area that was initiated to help secure water supply into the future. Prior to this investigation, resources were near or at full allocation raising concerns on groundwater availability for future growth. In addition, important values including groundwater dependent ecosystems require protection and seawater intrusion from pumping near the coastline is a threat to water quality.
The key outputs of the project for the Albany Groundwater Area included developing a 3D conceptual model incorporating airborne electromagnetic data (AEM), groundwater chemistry, isotope sampling and hydrograph evaluation. AEM data was used to map the sea water interface along the southern coastline and a combination of AEM and chemistry data was used to map the interface along Princess Royal Harbour. The conceptual model was used to build a numerical groundwater flow and density model capable of simulating groundwater systems under varying projected future climate scenarios and pumping regimes.
Outcomes of the investigation show that additional water is available for use without significant impacts. This investigation indicates that recharge from future 2030 and 2050 dry climate projections is between 18 and 13 GL per year respectively, an increase on the current estimates of 9 GL per year. Our knowledge of the groundwater systems has been greatly improved which will secure water supply to Albany for up to 20 years.