222-5 Diverging Elevation Trajectories of US Atlantic Coast Marshes: Resilient or Vulnerable?

Session: Delta Evolution from Rivers to the Shelf: Past, Present and Future Perspectives for Society (Posters)

Presenting Author:

Authors:

Abstract:

This study evaluates the vertical stability of tidal marshes along the U.S. Atlantic Coast using Surface Elevation Table (SET) and Marker Horizon (MH) records collected across a broad geographic network. We compiled SET-MH data from 564 monitoring stations across 21 coastal regions, representing measurements spanning up to two decades. From this, we developed a filtered dataset of 397 stations with sufficient temporal coverage to assess elevation trajectories based on surface elevation change (SEC), vertical accretion (VA), and shallow subsidence (SS = VA − SEC). Our preliminary results reveal a nearly even distribution between resilient and vulnerable marshes, with a comparable number of sites exhibiting either an elevation surplus or elevation deficit, and a smaller subset maintaining near-equilibrium conditions. These findings indicate that while shallow subsidence remains widespread, its impact is nearly balanced at other sites by root expansion. We observe regional clustering of elevation deficits, particularly in Georgia and Florida. Resilience is more dominant in the northeastern states, i.e., Massachusetts and Maine, whereas regions like New Jersey show greater spatial heterogeneity. Ongoing work to distinguish elevation response patterns between marsh types, and to compare relative sea-level data from tide gauges with surface elevation change to determine site-specific vulnerability to sea-level change, will further refine this spatial assessment of marsh dynamics and advance our understanding of coastal wetland resilience along the Atlantic coast.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-6054

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.