South-East Regional Water Balance Phase 1

A lack of understanding of the regional water balance is still a fundamental knowledge gap limiting the water allocation planning process for the Lower Limestone Coast Prescribed Wells Area (LLC PWA). A regional scale three-dimensional numerical groundwater flow model of the Lower South East region of

South Australia, and in particular of the LLC PWA, is required to:

• Help quantify regional water balance components as well as inter-relationships between regional recharge, flows between the unconfined Tertiary Limestone Aquifer (TLA) and the Tertiary Confined Sands Aquifer (TCSA), groundwater storage, and groundwater discharge.
• Address questions relating to specific components of the regional water balance that arise through the water allocation planning process.
• Contribute to a consistent framework for the future development of local-scale numerical groundwater flow models which may be designed to address local-scale issues and thereby further support water resources planning in the Lower South East region.
• Guide future technical work in the Lower South East region by refining the understanding of critical processes influencing water movement and availability, and by identifying locations where such processes are most significant.

Phase 1 of the South East Regional Water Balance project is the first component of a longer-term research program to develop a regional water balance model for the LLC PWA. It has involved:              

1. Development of a regional water balance framework;
2. A preliminary assessment of the spatial variability and indicative fluxes of groundwater discharge to the marine environment;
3. Assessment of the role of geological faults on regional groundwater flow and inter-aquifer leakage.