Airborne geophysical surveys of the lower Mississippi Valley demonstrate system-scale mapping of subsurface architecture

Burke J Minsley,J R Rigby,Stephanie R James,Katherine J Knierim,Michael D M Pace,Paul A Bedrosian,Bethany L Burton,Wade H Kress

doi:10.1038/s43247-021-00200-z

Burke J Minsley, J R Rigby + Show 6 more

Open Access

https://doi.org/10.1038/s43247-021-00200-z

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Abstract

The Mississippi Alluvial Plain hosts one of the most prolific shallow aquifer systems in the United States but is experiencing chronic groundwater decline. The Reelfoot rift and New Madrid seismic zone underlie the region and represent an important and poorly understood seismic hazard. Despite its societal and economic importance, the shallow subsurface architecture has not been mapped with the spatial resolution needed for effective management. Here, we present airborne electromagnetic, magnetic, and radiometric observations, measured over more than 43,000 flight-line-kilometers, which collectively provide a system-scale snapshot of the entire region. We develop detailed maps of aquifer connectivity and shallow geologic structure, infer relationships between structure and groundwater age, and identify previously unseen paleochannels and shallow fault structures. This dataset demonstrates how regional-scale airborne geophysics can close a scale gap in Earth observation by providing observational data at suitable scales and resolutions to improve our understanding of subsurface structures.

Highlights

The Mississippi Alluvial Plain hosts one of the most prolific shallow aquifer systems in the United States but is experiencing chronic groundwater decline
Groundwater withdrawals for irrigation made up ~20% of the total freshwater use for 2015 in the United States, of which 58% was extracted from the High Plains (HP, 20.3%), Mississippi Alluvial
As part of the new MAP assessment, a regional Airborne electromagnetic (AEM) survey was designed as the foundation for updating the hydrogeologic framework of the Mississippi River Valley alluvial aquifer (MRVA) together with updated borehole compilations[39,41]. In this first-of-its-kind regional AEM study, we demonstrate the utility of airborne geophysical data for improving understanding of the structure of the surficial aquifer and surrounding geological formations that are of critical importance for effective water resource management in the region and have broader implications for geologic mapping and hazards investigations

Summary

Introduction

The Mississippi Alluvial Plain hosts one of the most prolific shallow aquifer systems in the United States but is experiencing chronic groundwater decline. In this first-of-its-kind regional AEM study, we demonstrate the utility of airborne geophysical data for improving understanding of the structure of the surficial aquifer and surrounding geological formations that are of critical importance for effective water resource management in the region and have broader implications for geologic mapping and hazards investigations.

Results

Conclusion