Geology topics

Emily N. Fromenthal

Publications and source records attributed to Emily N. Fromenthal.

2 recordsLinked to original sources

USGS2025

How high? Identifying elevation thresholds to guide coastal marsh restoration

Introduction Coastal marshes are highly valuable ecosystems facing threats from rising sea levels and intensifying storm events. To elevate marsh surfaces and prevent loss of ecosystem services, the beneficial use of dredged material (BUDM) is increasingly being implemented across the United States. Objectives The objective of this study was to aid decision-makers and restoration practitioners by identifying elevation thresholds that control the optimal function of Spartina patens -dominated marshes along the Texas Coast. Methods This study was conducted in the coastal marshes of the J.D. Murphree Wildlife Management Area (Texas). We collected elevation and vegetation cover data along ecological transition zones in marshes nourished with BUDM to identify elevation thresholds that define zones of optimal plant survivorship and growth. Results We identified lower (−0.05 m mean high water, MHW) and upper (0.26 m MHW) elevation thresholds that defined transitions to open water and unvegetated bare ground, respectively. Elevation targets ( T ) and elevation target zones, which defined areas with the greatest vegetation cover, were determined for S. patens ( T : 0.11 m, target zone: −0.06 to 0.26 m MHW), S. alterniflora ( T : 0.00 m, target zone: −0.12 to 0.10 m MHW), and Distichlis spicata ( T : 0.17 m, target zone: 0.07–0.25 m MHW). Conclusions Our analyses provide species-specific elevation targets for coastal marsh restoration through BUDM, which can improve restoration outcomes for coastal wetlands.

Texas↗

USGS2024

Accelerating elevation gain indicates land loss associated with erosion in Mississippi River Deltaic Plain tidal wetlands

In recent years, the Mississippi River Deltaic Plain (MRDP) has experienced the highest rates of wetland loss in the USA. Although the process of vertical drowning has been heavily studied in coastal wetlands, less is known about the relationship between elevation change and land loss in wetlands that are experiencing lateral erosion and the contribution of erosion to land loss in the MRDP. We quantified relationships of elevation change and land change in ten submerging tidal wetlands and found that, despite significant land loss, elevation trajectories in seven of the land loss study sites were positive. Furthermore, we observed an acceleration in elevation gain preceding the conversion from vegetated marsh to open water. To identify regional contributions of lateral erosion to land loss, we quantified the relationship of elevation change and land change in 159 tidal marsh sites in the MRDP. Approximately half the sites were persistently losing land, and 82% of these sites were vulnerable to erosion, identifying erosion as a dominant mechanism of coastal wetland loss in this region. Notably, the sites that were vulnerable to erosion were experiencing land loss while also gaining elevation, and sites with the highest land loss exhibited accelerating elevation gain. Together, these data illustrate that (1) erosion is a dominant mechanism of wetland loss in the MRDP, (2) accelerated elevation gain is an indicator of erosion, and (3) consideration of elevation change trajectories within the context of land change is critical for providing accurate coastal wetland vulnerability assessments.

Louisiana↗