This dataset represents the intrinsic aquifer vulnerability to contamination evaluated for unconfined aquifers in Fitzroy, based on the DRASTIC method (Aller et al. 1987). This semi-quantitative but spatially distributed method is especially suited for regional investigations with limited data availability. The DRASTIC index is calculated based on seven components: Depth to groundwater, net recharge, Aquifer media, soil media, topography (slope), impact of vadose zone and hydraulic conductivity of the aquifer (Aller et al. 1987). Areas with unconfined aquifers or with shallow water tables receive a high index and, vice versa, area with fractured rock aquifers and deep water tables have a low index.
For the Upper Spencer Gulf region, based on the spatial distribution of index values, unconfined aquifer contamination due to a spill at the surface is considered not possible if the drastic index is less than 70. In grid cells with DRASTIC index between 70 and 100, unconfined aquifer contamination due to spill at the surface is considered possible but not material. In areas with DRASTIC indices above 100, unconfined aquifer contamination due to a spill at surface is considered material and avoidance and mitigation strategies are considered.
Further information about the DRASTIC map and the development of this map is described in Holland et al. (2024) [Securing water for an emerging Australian hydrogen industry - Methods report].
