b'AEM 2023Short abstractsUsing airborne electromagnetics to improve depth toa profound reliance of knowledge of water, species and country, bedrock estimates in Wisconsin has been critical to ensure the survival of indigenous peoples in a dry landscape, through the role of traditional knowledge in Burke Minsley1, Jade Crosbie1, Jim Duncker2, Daniel Feinstein3,finding and protecting cultural landscapes. Indigenous knowledge Lisa Haas4, Dave Hart4, Randy Hunt3 and Matt Komiskey3 and methodologies can provide new (but old) evidence that is 1. U.S. Geological Survey, Denver, CO, United States culturally appropriate, and which generates a cultural safe space 2. U.S. Geological Survey, Champaign, IL, United States with indigenous researchers and communities leading. The aim is 3. U.S. Geological Survey, Madison, WI, United States to present protocols and principles to shift the research paradigm 4. Wisconsin Geological and Natural History Survey, Madison, WI,away from indigenous peoples being the researched under non-United States indigenous research methodologies to becoming the researchers. This allows the indigenous scientist to derive the terms, questions Depth to bedrock is often an important factor in hydrologicand priorities of what is being researched, how the community is systems because hydraulic properties of bedrock and overlyingengaged, and how the research is delivered.sediments are typically appreciably different. For example, the thickness of glacial sediments overlying bedrock in Wisconsin controls the routing of groundwater in surficial aquifers andThe Valen Prospect: Its SPM, No its not,Yes it is! its connection with surface water bodies such as lakes andNo wait.wetlands. In fractured bedrock environments, shallow bedrock can be vulnerable to degraded water quality when contaminantsTimothy Munday1, Mike McMillan2, Rod Paterson3, Daniel Sattel4, at the surface infiltrate quickly through permeable formations.Camilla Srensen5 and Noelene Dorn6Here, airborne electromagnetic surveys were acquired in three1. CSIRO, Kensington, Perth, WA, Australiadifferent parts of Wisconsin, totalling more than 5700 flight2. Computational Geosciences Inc, Vancouver, Canadaline-km, to improve understanding of depth to bedrock, the3. Intrepid Geophysics, Brighton, VIC, Australialithologic composition of overlying sediments, and as input4. EM Solutions LLC, Golden, Colorado, USAstructure for groundwater model development. 5. Aarhus Geosoftware, Aarhus, Denmark6. ElectroMagnetic Imaging Technology Pty Ltd, Perth, WA, AustraliaAEM survey of the Neretva Delta (Croatia): a case study for hydrogeology The choice of systems and interpretation approaches for the exploration for critical mineral systems under a complex and John Moilanen1, Pietro Teatini2, Giulio Vignoli3 and Veljko Srzi4 varying regolith cover using airborne electromagnetics, can be informed by forward modelling methods. However, the direct 1. LLC Geotechnologies, Povarovo, Russia assessment of systems and modelling algorithms using data 2. University of Padua, Padova, Italy acquired under real survey conditions can be equally informative. 3. University of Cagliari, Cagliari, Italy For example, it provides an opportunity to assess the effects 4. University of Split, Split, Croatia of real geological variability and noise, arising in a true survey Groundwater salinisation is a serious problem affectingconfiguration for different systems, and the artefacts that may numerous areas of the world, and Neretvas delta in Croatia isresult from the use of different inversion codes. Here we discuss the one of them. Airborne electromagnetics is already widely usedapplication of 1, 2 and 3D inversion approaches to resolving the to feed data-driven decision and management processes withgeometry and complexity of the geology in an area on the South accurate (hydro) geomodels and, by doing so, to mitigate theAustralian side of the Musgrave province and consider modelled detrimental effects of salinisation. responses from coincident lines of fixed wing (SPECTREM-Plus and TEMPESTHigh Moment), and heliborne (VTEM and SkyTEM) time In this perspective, in 2021, an airborne electromagnetic surveydomain EM systems over a known (from ground EM and drilling) was flown over about 100 km2. The overall goal of the surveydeep, steeply dipping, conductor - the Valen Prospect.was to better understand the hydrogeology of the plain leading to a more quantitative assessment of the saltwater intrusion andAll inversion methods and AEM systems contributed to our possible preferential paths. understanding of geological variability and structural complexity, although all generate smoothed versions of geological reality. Here, we present the results of data processing and inversion.Results from the 1D inversions appear to map geological We built a (pseudo-)3D resistivity model based on 1D forwardvariability and complexity in the near surface (regolith character?) approximation. And we compare it against ground-basedin greater detail compared to those from the 2 and 3D inversions, electrical measurements. According to the available boreholes,even though the geology is recognisably 3D in character. The freshwater is related to a relatively resistive unit. Valen Prospect characterised as a distinct, small, and narrow late time anomaly, is modelled in 1D, albeit deeper than drilling and Indigenous knowledge and methodologies to informground EM suggests. While the 2 and 3D models have good global science and data capture data fits, in some instances they failed to fit measured data at late time, consequently overlooking Valen. It was suggested that Bradley Moggridge problems with fitting the anomaly at late times may be the result Kamilaroi Nation of regolith-related superparamagnetism (SPM) in the near surface University of Canberra, Centre for Applied Water Science which often beset AEM data sets in Australian settings. However, decay-rate analysis of the Valen anomaly suggests a deep Indigenous knowledge and methodologies are a missingconductor response for the SkyTEM, SPECTREM and TEMPEST component in science in Australia. On this dry, flat and ancientsystems. The decay rate of the corresponding VTEM anomaly continent Traditional Knowledge has been passed on fromsuggests an SPM response. However, the shape of the VTEM decay generation to generation for millennia (over 65 000 years). This isalso suggests the presence of deeper conductive material.61 PREVIEW AUGUST 2023'