Groundwater resources that sustain small Indigenous communities in remote parts of northern Australia are often poorly characterised, in part due to their remoteness and the economics of undertaking field investigations. The Warruwi community on South Goulburn Island in the Northern Territory is completely reliant on groundwater for its livelihood. Recent consecutive poor wet seasons highlighted both: (i) the sensitivity of the island's water resources to short-term rainfall variability, and (ii) the inadequacy of the island's water infrastructure for meeting water demand during dry periods. An integrated approach was taken to underpin the longer-term water security for the community and to better characterise and quantify the island's water resources and infrastructure requirements. This involved: an airborne electromagnetic (AEM) survey supported by ground geophysics; a hydrogeological survey including environmental tracer analysis; and a desktop study including an annual groundwater balance. Spatial analyses of the AEM data, lithology, groundwater levels and salinity identified a thin (~20m), storage-limited unconfined freshwater `lens' system overlying a regional aquitard. Groundwater level analyses combined with tracer interpretation characterised a hydrodynamic flow system with short flow paths (<2.5 km) and short mean residence times (MRTs) of ~15 years. A groundwater balance for the freshwater system confirmed that community water demand can be met with the existing resource, although additional water infrastructure and a more strategic management approach was required to better utilise the resource.

Open-Access Online Publication: March 03, 2023