Kellett, R.L.; Sahoo, T.R.; Herpe, M.; Berhe, D.T. 2026 Aqua Intel Aotearoa Phase 3: Gisborne SkyTEM hydrogeological interpretation of Poverty Bay flats. Aqua Intel Aotearoa report 2025/09; GNS Science consultancy report 2025/147. 49 p. https://doi.org/10.21420/3GMS-3K05
Abstract
This report contributes to Aqua Intel Aotearoa investigations in the Gisborne district, which included data collection of 2137 line-km of airborne electromagnetic (AEM) in February 2024 over Poverty Bay flats. This report focuses on 3D hydrogeological interpretation of the geophysical data, building on previous reports of data collection, processing and modelling. This interpretation integrates the AEM resistivity models with borehole data, groundwater chemistry and regional geology to delineate key hydrogeological units that are visible as resistivity contrasts. The AEM resistivity values of these hydrogeological units were also compared to groundwater chemistry related to salinity. To support future modelling of the aquifer systems, the interpreted hydrogeological units are provided as digital attachments to this report in multiple formats: • Upper hydrogeological unit (HU1), which contains the shallow aquifers.; • Intermediate hydrogeological unit (HU2), which represents the main confining layer.; • Deeper hydrogeological unit (HU3), which consists of deeper aquifers and extends to the base of Quaternary sediment (auths)