USING 3-D GEOLOGIC MODELS TO DETERMINE AQUIFER EXTENTS AND THICKNESSES ACROSS NEW MEXICO

The New Mexico Bureau of Geology and Mineral Resources (NMBGMR) has been investigating the use of 3D geologic models to better quantify groundwater resources across New Mexico, and with the planned release of a High Plains model in 2025, we will have modeled the entire SE quarter of the state. The exact methods for developing these hydrogeologic models varied for each region studied based on the available funding and the types and extent of regionally available data. This important work has been funded by the Healy Foundation since 2016 and, more recently, by the USGS as part of their 3D GeoFramework initiative. While this funding has been generous, it has historically been insufficient for any new large-scale data collection, and the models are created from carefully compiled and reviewed publicly available datasets. Typical datasets included in these modeling efforts include surface geologic mapping, digitized cross-sections, water well drilling logs, and geophysical logs from oil and gas well exploration. Structural geologic models are created from these datasets in ArcGIS using ESRI interpolation techniques such as the Topo-to-Raster tool. Groundwater surface elevations are then analyzed by importing hydrologic data from groundwater level monitoring data sources such as the USGS and the Healy Collaborative Groundwater Monitoring Network at NMBGMR. Water quality data is also included in the models to understand the extent of both fresh and brackish water. Aquifer thickness is determined through a combination of geologic surface controls and water quality variations with depth.

The final result of these efforts is free, accessible digital aquifer maps that can fulfill numerous needs at the local, state, and federal levels. Some examples of the benefits these models provide include better management of existing groundwater resources for communities, increased confidence in well drilling operations for well owners, better informed regional water planning efforts for decision-makers, and greater protections of existing water quality. The models are available for download as GIS map packages, KMZ files, or 2d maps included in our Open-File Reports found at the NMBGMR website (www.geoinfo.nmt.edu).