59ab3c57-c226-59dc-86a1-d97bec448af2 urn:uuid en UTF-8 nonGeographicDataset nonGeographicDataset 2025-09-20T10:34:33 creation ISO 19115 2016 Drastic index map for the Pilbara region 59ab3c57-c226-59dc-86a1-d97bec448af2 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 Pilbara 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 100. In grid cells with DRASTIC index between 100 and 125, unconfined aquifer contamination due to spill at the surface is considered possible but not material. In areas with DRASTIC indices above 125, unconfined aquifer contamination due to a spill at surface is considered material, so 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]. drastic_pilbara.tif documentDigital BIN