Fresh groundwater stored in coastal aquifers constitutes an important resource for humans and the natural environment. However, many Australian coastal aquifers are vulnerable to seawater intrusion (SWI), which is the landward encroachment of seawater into coastal aquifers. SWI can significantly degrade water quality and reduce freshwater availability.
In response to the threat posed by SWI, Geoscience Australia and the National Centre for Groundwater Research and Training, in collaboration with state and territory water agencies, have undertaken a national-scale assessment of the vulnerability of coastal aquifers to SWI. This report describes one of the project's technical components, the Mathematical Analysis. This project developed a method for first-order assessment of SWI extent under current conditions and propensity to change in SWI extent due to various stressess associated with climate change and future extraction. The method is an extension to an existing analytical sharp-interface solution and involves the use of partial derivative to quantify rates of change in SWI extent for the various stresses.