Vulnerability of Louisiana\u2019s coastal wetlands to present-day rates of relative sea-level rise

Krista L Jankowski,Anjali M Fernandes,Torbjörn E Törnqvist

doi:10.1038/ncomms14792

Krista L Jankowski, Anjali M Fernandes + Show 1 more

Open Access

https://doi.org/10.1038/ncomms14792

Copy DOI

Journal: Nature Communications	Publication Date: Mar 14, 2017
Citations: 225	License type: open-access

Affiliation: Tulane University, University of Connecticut

Abstract

Coastal Louisiana has lost about 5,000 km2 of wetlands over the past century and concern exists whether remaining wetlands will persist while facing some of the world’s highest rates of relative sea-level rise (RSLR). Here we analyse an unprecedented data set derived from 274 rod surface-elevation table-marker horizon stations, to determine present-day surface-elevation change, vertical accretion and shallow subsidence rates. Comparison of vertical accretion rates with RSLR rates at the land surface (present-day RSLR rates are 12±8 mm per year) shows that 65% of wetlands in the Mississippi Delta (SE Louisiana) may keep pace with RSLR, whereas 58% of the sites in the Chenier Plain (SW Louisiana) do not, rendering much of this area highly vulnerable to RLSR. At least 60% of the total subsidence rate occurs within the uppermost 5–10 m, which may account for the higher vulnerability of coastal Louisiana wetlands compared to their counterparts elsewhere.

Highlights

Coastal Louisiana has lost about 5,000 km[2] of wetlands over the past century and concern exists whether remaining wetlands will persist while facing some of the world’s highest rates of relative sea-level rise (RSLR)
We find that many wetland sites across coastal Louisiana, and especially those concentrated in its westernmost portion, exhibit an accretion deficit that results in vulnerability to modern rates of RSLR
We find that median Mississippi Delta (6.0 mm per year) and Chenier Plain (5.8 mm per year) SS rates are strikingly similar (Fig. 2c, Table 1)

Summary

Introduction

Coastal Louisiana has lost about 5,000 km[2] of wetlands over the past century and concern exists whether remaining wetlands will persist while facing some of the world’s highest rates of relative sea-level rise (RSLR). Available SEC rates are derived from relatively small case studies in coastal Louisiana[17,18,19,20] (o20 sites; Supplementary Table 1) and have produced results that are inconclusive as to whether RSLR outpaces wetland surface-elevation gain.

Results

Conclusion