Diagram showing how the authors used GPS, anchors, and fiber-optic strain meters to measure coastal subsidence.
This suite of GPS, anchors, and fiber-optic strain meters is the first of its kind to measure coastal subsidence. Credit: Zumberge et al. [2022], Figure 2
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Earth Surface

In many coastal regions, rising sea levels are compounded by subsidence, the sinking of the land surface. In coastal Louisiana, for example, sea level rise of about 4 millimeters per year is compounded by subsidence that is 9 millimeters per year averaged across the state.

Zumberge et. al [2022] provide the results of a new field campaign to measure this subsidence in unprecedented detail using a fiber-optic strain meter capable of detecting subsidence on the order of microns (millionths of a meter), as well as GPS and measurements of sediment accumulation on the surface. Over three years, the strain meters detected very little subsidence in the 38-meter-thick package of sediments deposited in the past 11,000 years but significant subsidence in the top meter of sediments near the surface.

These new measurements support a growing body of literature that most coastal subsidence is the compaction of shallow sediments very near the surface, while deeper sediments remain relatively stable under natural conditions. These measurements will be used to engineer land building river diversions and train next generation of models focused on the compactable sediments of coastlines. 

Citation: Zumberge, M. A., Xie, S., Wyatt, F. K., Steckler, M. S., Li, G., Hatfield, W., et al. (2022). Novel integration of geodetic and geologic methods for high-resolution monitoring of subsidence in the Mississippi Delta. Journal of Geophysical Research: Earth Surface, 127, e2022JF006718. https://doi.org/10.1029/2022JF006718

—John Shaw, Associate Editor, Journal of Geophysical Research: Earth Surface

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