Development of a Novel Assessment Framework for Managed Aquifer Recharge (MAR) Site Selection: the Broken Hill Managed Aquifer Recharge (BHMAR) Project, NSW, Australia

Lawrie, K.C., Brodie, R.S., Clarke, J., Ransley, T., & Gibson, D.
Geoscience Australia, GPO Box 378, ACT 2601, Australia. Email RossS.Brodie@ga.gov.au
An initial scoping study identified 5 broad areas within a 150km radius of Broken Hill where MAR storage options and/or groundwater extraction could provide alternative sources of water for the town. In order to select a singly area, and focus the next phase of hydrogeological investigations, an assessment framework was developed for MAR site selection.
Specific options assessed, included:
 Enhanced recharge or extraction of fresh to brackish quality water from near-surface (0-30m) alluvial aquifers and river flush zones;
 Extraction of fresh to saline groundwater from intermediate-level (30-120m) aquifers; and/or use of these formations for MAR;
 Extraction of brackish groundwater or use of storage in deeper (>250m) aquifers;
 Groundwater resource and MAR potential of alluvial fan systems;
 Capture of groundwater seepage from existing reservoirs.
The assessment framework utilised a matrix approach, and prioritised two key criteria:
 The likelihood of technical success: accounting for the probability that the required groundwater resource is likely to be present, discoverable with the available technology, and the water supply alternative can be implemented;
 The likelihood of negative consequences: accounting for the potential and significance of impacts to the water resource, ecosystems and other groundwater users if the option was to be implemented.
The approach also included an analysis of the characteristics of key aquifer systems in each of the 5 priority areas, with a focus on a review of their internal architecture and yield potential, in addition to their bounding relationships.
As a result of this risk assessment, the Darling Floodplain was ranked as the highest priority, and the BHMAR Project established. Final project boundaries were chosen based on the use of salinity yield maps to delineate zones of possible fresh to brackish groundwater in target aquifers. An explanation of the assessment framework is the focus of this paper.