Improved Imaging of the Large‐Scale Structure of a Groundwater System With Airborne Electromagnetic Data

Abstract

With climate change and population growth, there is increasing concern about the depletion of groundwater resources. Evidence of this is a petition signed by over 1,300 scientists from 100 countries calling for action to ensure that groundwater benefits society now and into the future (Gleeson et al., 2019). A groundwater model is the foundation on which to build sustainable groundwater management. Required to inform the development of the groundwater model is information about the subsurface that captures spatial heterogeneity at the level needed as the input for flow modeling.All groundwater models include some representation of the large-scale structure of the groundwater system-the hydrogeologic units and other major features relevant for modeling flow. We define "large" to be the scale at which we represent the architecture of the subsurface in terms of the boundaries between areas with significant differences in hydrogeologic properties, for example, the boundary between an aquitard and aquifer, the top of the bedrock. Information derived from driller's logs, recorded when wells are drilled, is typically used to build the model. The logs potentially provide valuable information at point locations, but the quality of the driller's logs

Isogeochemical Characterization of Mountain System Recharge Processes in the Sierra Nevada, California

“…The was based on the geological cross-section A-A' (Figure 2a) of Lofgren and Klausing (1969) and was confirmed by a recent large-scale geophysical investigation (Kang et al, 2022). This division was not applied to the Western Valley Aquifer (WVA) wells close to the historical Tulare Lake.…”

Mapping Hydrogeological Structures Using Transient Electromagnetic Method: A Case Study of the Choushui River Alluvial Fan in Yunlin, Taiwan

“…Therefore, it is more convenient to do perform the 1D inversion if the lateral rate of change of the subsurface resistivity is small. One of the challenges in TEM inversion is uniquely estimating model parameters, i.e., resistivity and thickness, simultaneously [1]. The inverse problem is always problematic unless care is taken in the inversion process.…”

“…However, 1D models do not strictly match resistivity log values. This may be due to (1) the sensitivity difference between the two geophysical data sets and (2) the over/underestimation of the initial model. TEM is sensitive to the conductive target, whereas the resistivity log is sensitive to the resistive target.…”

“…The heterogeneous distribution of groundwater in space and time is linked to those structural features. It is essential to establish rules based on those features for sustainable groundwater resource management; to use the resource appropriately for the present and long term in the future [1][2][3][4][5][6]. Improper groundwater management leads to inappropriate groundwater utilization [7].…”

“…Danielsen [25] mapped a low-resistivity Tertiary clay layer in Denmark by collecting using different TEM systems and combining high-quality data. Further, 2D and 3D regional hydrogeological structures are mapped based on the spatially constrained 1D inverted large volume of AEM data in the Central Valley of California [1,3].…”