As part of developing a water balance for the GAB and to inform water management policies, current and historical water use estimates were required.
The historical and water use estimate involved consideration of artesian, sub-artesian bores which are utilised for a range of purposes, including stock and domestic, industrial, mining, town water supply and agriculture. Consideration in the estimate towards ‘free-flowing’ bores, bores capped / piped under saving schemes such as GABSI and abandoned bores was also required. For the current water use estimate, a previously developed method by OGIA for the Surat CMA was adopted, adapted and scaled to include the remaining portions of the QLD GAB and provide an estimate on a bore-by-bore basis. The historical water use involved a more complex approach, with consideration given to the declining pressure in artesian bores.
The primary data used in the assessment was from the DNRM Groundwater database, utilising bore types, conditions, status, flow estimates and yields. The results of the assessment provided a water use time-series from 1900 to 2015 for the aquifer groupings adopted by the study. Due to the large spatial extent of the GAB in QLD, current water use was presented using spatial mapping comprising 50kmx50km grid of the water use.
The assessment resulted in historical water use profiles, and estimates of current water use presented in visual format which has provided valuable information and an alternative approach to assist water management of the GAB in QLD.