Novel Integration of Geodetic and Geologic Methods for High‐Resolution Monitoring of Subsidence in the Mississippi Delta
Abstract
Land‐surface subsidence is a major contributor to land loss in many river deltas. New approaches yielding high‐resolution data are needed to parse the relevant driving forces. In 2016, we established a novel “subsidence superstation” ∼2 km from the Mississippi River in coastal Louisiana (USA) to measure compaction in a global reference frame as a function of depth in Holocene sediments and deeper subsidence. The site features three borehole optical fiber strainmeters to obtain continuous records of displacement between ∼1.3 m below the surface and depths of ∼11, 25, and 38 m. These data are complemented by an adjacent station providing hydrologic data and near‐surface compaction. We also installed three GPS antennas, one of which is mounted to a rod cemented into the Pleistocene basement. A core from one of the boreholes provides insight into the sediment properties of the entire Holocene succession. Five years of records reveal the compaction rate in the material between 1.3 and 38 m is likely less than 0.25 mm/yr. The GPS records yield a subsidence rate of 2.5 mm/yr regardless of the depth of the anchor, thus corroborating the low compaction rates observed by the strainmeters. The new instrumental records show that current subsidence at this location is governed mostly by deformation of the Pleistocene or underlying strata rather than compaction of Holocene material, with the exception of the uppermost meter. The methodology represents an important new approach to mapping subsidence rates at varying depths, providing insight into the mechanisms governing delta subsidence.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 01, 2022
- Source ID
- 10.1029/2022jf006718
Entities
People
- Donald Elliott
- Elizabeth L Chamberlain
- Guandong Li
- Jonathan G. Bridgeman
- Mark A. Zumberge
- Mead A. Allison
- Michael S. Steckler
- Surui Xie
- Timothy H. Dixon
- Torbjörn E Törnqvist
- William Hatfield
Organizations
- Columbia University
- Tulane University of Louisiana
- United States Army Corps of Engineers
- University of California, San Diego
- University of South Florida
- Wageningen University & Research