A Hydrogeophysical Survey Utilising the <scp>sTEM</scp> and <scp>sTEMprofiler</scp> Systems: Transient Electromagnetic Data and Resistivity Models

ABSTRACT Transient electromagnetic (TEM) methods are widely applied to characterise subsurface geological structures relevant to groundwater management. Here, we present a TEM dataset and the resulting resistivity models (available at https://doi.org/ 10.5281/zenodo.16894039 ) from a hydrogeophysical survey in northwestern Denmark aimed at mapping buried Quaternary valley systems. The data were collected with the newly developed sTEMprofiler system, a portable offset‐loop TEM system and supplemented by stationary sTEM central‐loop soundings for deeper penetration. The sTEMprofiler enabled rapid data acquisition of 319 soundings across 300 ha in 3 days. Data were processed and inverted using spatially constrained inversion, yielding reliable resistivity models with average data residuals within the standard deviation of the measurements, and with depths of investigation of 100–150 m for the sTEMprofiler and &gt; 300 m for the largest central‐loop configuration (depending on subsurface geology and noise conditions). The resistivity models show complex Quaternary valley infills incised into Paleogene clays, uplifted limestone and low‐resistivity zones within the limestone, likely caused by residual saline porewater. In addition to the use of the resistivity models for local geological interpretation and hydrological modelling, the dataset offers considerable reuse potential. By providing raw data, system setup files, resistivity models and residuals, it enables researchers to explore a wide range of applications, including benchmarking and comparing inversion methods (deterministic, probabilistic or machine learning approaches), performing joint inversions, integrating resistivity models into geological and hydrological studies, and training or teaching sTEM data processing and inversion workflows.