Managed aquifer recharge opportunity mapping in New South Wales

The NSW Groundwater Strategy aims to enhance community and industry resilience through sustainable groundwater use. The use of managed aquifer recharge (MAR) is an innovative approach to achieve this goal. This data collection contains the input files, scripts and output files used to assess MAR opportunities for groundwater resource units across NSW. The main outputs consist of spatial grid files (.tif) representing areas where feasibility criteria are met, gridded storage volume calculations, and summary tables of results for resource units.\nLineage: The assessment of NSW Groundwater Sources (GWS) focused on areas defined in water sharing plans under the Water Management Act 2000. Certain GWS areas were filtered out based on factors like unfavourable geology, limited extent, shallow water tables, high groundwater-surface water interactions, saline groundwater, and high topographic slope. GWS areas within the NSW portion of the Great Artesian Basin (GAB) and the Gunnedah-Oxley Basin were also eliminated due to historical pumping and demand levels below extraction limits. The NSW GAB Shallow resources were excluded due to extraction limits significantly higher than licensed entitlements.\n\nA spatial screening assessment was conducted to eliminate areas where MAR was unlikely to be feasible. Stochastic spatial criteria thresholds were applied to account for uncertainty. Percentages of iterations where all spatial criteria were met were used to calculate storage potential at 25%, 50% and 75% screening confidence intervals.\n\nAssessment of unconfined aquifer potential for MAR focused on infiltration-based recharge. Feasibility depends on sediment permeability and hydrogeological characteristics. Seven spatial screening criteria were used for MAR assessment. Infiltration volumes were calculated based on unsaturated depth and porosity. Spatial variation in porosity was assumed to be related to aquifer thickness. Alluvial aquifer thickness data was rescaled using minimum and maximum porosity values based on modelled areas. Potential storage volumes were calculated as cell areas multiplied by depth to water minus 4 m (to avoid water logging) multiplied by porosity.\n\nFive spatial screening criteria were used to assess the confined aquifer MAR opportunity, determining well-injection feasibility. Potential recharge capacities were calculated using the Theis solution that is applicable to both extraction and injection cases. The resulting head response depends on aquifer transmissivity, storage coefficient, and injection rate. To prevent over-pressurization and impacts on neighbouring bores, a maximum allowable head increase of 1 m was set at the cell edge over an injection cycle of 90 days.\n\nFor further information refer to the final technical report:\nGonzalez, D. and Page, D. (2024) Managed Aquifer Recharge opportunity mapping in New South Wales to support irrigated agriculture. Final technical report for the NSW Department of Climate Change, Energy, the Environment and Water and the National Water Grid Authority. CSIRO, Australia.