Science, Technology and Engineering

Environmental Geoscience

Postgraduate Projects

Groundwater resources and salinity associated with granites in the upper Wimmera, western Victoria

Sarah Hagerty

Supervisor: Dr John Webb

The Wimmera Basin in western Victoria suffers from land and water degradation due to increased salt mobilisation since the catchment was cleared for agriculture; almost 22000 ha of land is visibly affected by salinity and 56000 ha is currently at high risk of salinisation. The Wimmera Regional Salinity Action Plan 2005-2010 identified the major Groundwater Flow Systems (GFSs) in the Upper Wimmera, and suggested that low relief, highly weathered granites in the region have the potential to contribute significant salt loads to the catchment: this is a threat to down-basin surface water and groundwater systems. The report also highlighted the potential for high relief, less weathered granites to provide good quality water for local landholders. The interactions between groundwater in the granites and the surrounding basement aquifer (St. Arnaud Group) and alluvial aquifer (Calivil Formation) are largely unknown.

This study proposes to investigate these GFSs at a smaller, more detailed scale, to provide a thorough understanding of groundwater movement and chemistry in all aquifers in the Upper Wimmera. Interactions between groundwater and surface water will also be investigated. The main outcomes of the project will be delineation of potential water resources for local landholders and a detailed understanding of salinity processes associated with granites in the Upper Wimmera, including options for salinity mitigation and prevention.

The project is supported by the Wimmera Catchment Management Authority, and co-supervised by Phil Dyson (Phil Dyson and Associates) and Mark Hocking (Hocking et al.).