A key challenge for managing the aquifers of the Great Artesian Basin (GAB) is the limited available data for private groundwater use. Estimates of unmetered private groundwater use are critical for conceptualisation of groundwater systems and for understanding the system response to the current and future stresses. In the absence of an existing methodology, the Queensland Government’s Office of Groundwater Impact Assessment (OGIA) developed a demand-based method to estimate unmetered stock and domestic (S&D) groundwater use.
The method integrates publicly available datasets including property grazing potential and availability of other water supplies to derive a range of groundwater use estimates. The methodology also distributes the demand for groundwater use across existing bores and across screened geological formations based on bore construction and OGIA’s formation attribution assessment. The method has been applied to the Surat and southern Bowen basins.
This presentation will provides an overview of the demand-based method, highlighting new understanding of the temporal and spatial distribution of groundwater use in Surat and southern Bowen Basins. Results were validated at the bore level with limited metered bore data, and at the sub-regional level from census data and landholder survey information. Across the Surat Basin, comparisons with previous estimates indicate a reduction in S&D water extraction from approximately 80,000 to 25,000 ML/yr.
OGIA’s 2016 methodology was applied to the Eromanga and Carpentaria basins of GAB to support the review of the Queensland Water Resource (Great Artesian Basin) Plan 2006. Over the past two decades, resource development activities including coal seam gas (CSG) extraction have rapidly expanded in the Surat and southern Bowen Basins, sub basins of the GAB. It is important for resource managers to be able to differentiate between the impacts of groundwater extraction during resource development activities and the impacts of groundwater extraction for consumptive uses. The method and underlying principles of the estimation methodology are broadly applicable to unmetered S&D extraction from other regional groundwater flow systems.