20 Aug 2025

Trade-offs Between Field and Remote Geomorphic Monitoring of Coastal Marsh Restoration Sites

Abstract: Coastal marsh restoration presents geomorphic monitoring challenges because these sites are often remote or inaccessible, and time and financial resources for field data may be limited. Yet, elevation and shoreline characteristics contribute to the overall health and longevity of coastal marshes. The expansion of Uncrewed Aircraft System (UAS) technology and new satellite platforms offer opportunities to complement ground-based geomorphic monitoring and overcome the challenges of traditional field methods. Here, we compare field-based and remote-sensing approaches to monitor two restored coastal wetlands in Louisiana. At Spanish Pass, methods for measuring site elevation, shoreline position, and shoreline geomorphic types were compared. Ground surveys strongly correlated with UAS-lidar digital elevation model (DEM) elevations (R2 = 0.97. UAS and satellite imagery were accurate to within 3 meters of field-shoreline positions, and UAS-lidar-derived shorelines had the lowest error. At LaBranche, UAS-lidar DEM data were paired with airborne lidar and legacy ground surveys to track temporal changes in elevation, indicating minimal elevation change. The study demonstrates the accuracy and utility of satellite and UAS remote sensing for monitoring shoreline positions and elevations but notes that shoreline classifications could be improved with additional quantification. These findings help practitioners assess the trade-offs and benefits of various monitoring methods.

21 Mar 2024

A Beneficial Placement Decision Support Framework for Wetlands: Case Study for Mobile Harbor, USA

Abstract: The US Army Corps of Engineers, in the responsibility of maintaining navigational infrastructure, has a unique opportunity to improve coastal wetland resiliency and conserve coastal natural infrastructure through the beneficial use of dredged material for wetland restoration. Opportunities are widespread, and tools such as biophysical models can aid coastal managers in assessing habitat vulnerability and planning restoration. In this study, the Marsh Equilibrium Model was utilized in concert with observed data to predict future conditions and evaluate potential effects of beneficial use of dredged material to restore marshes in Mobile Harbor, Alabama. A range of site conditions and two restoration strategies were considered, and the subsequent impact to dredged material management area volumes evaluated. Results showed that wetland restoration via the thin-layer placement of dredged material can restore marsh elevation to combat sea level rise and conserve fill capacity at dredged material management areas. This approach is demonstrated for adoption nationwide by coastal managers.

18 Oct 2023

Guidelines for How to Approach Thin-Layer Placement Projects

Abstract: Historically, dredged material (DM) has been placed at the nearest available placement site. There has been an increasing trend of beneficial use projects recently, often using innovative methods. Thin-layer placement (TLP) involves one- to two-foot-thick DM placement, compared to traditional, thicker sediment placement applications, to restore coastal wetlands. The main idea of TLP is to promote the natural recolonization or reestablishment of habitat and benthic species. These guidelines present a roadmap of TLP’s evolution and offer easily digestible examples and considerations for TLP applications in wetlands and open-water environments. Offered as a tool to the practitioner, the eight chapters of these guidelines cover the history of TLP, characterization of the project area, setting goals and objectives, project design, construction considerations, monitoring and adaptive management, knowledge gaps, and future research needs. Several case studies are presented as examples of how such applications have been implemented and highlight lessons learned, particularly best-management practices. These guidelines offer consideration of TLP as a critical component in the project development phase, a tool for the sustainable management of DM, and a method that may create, maintain, enhance, or restore ecological function while supporting navigation channel infrastructure and providing flood risk management benefits.

11 Sep 2023

Selection of a Time Series of Beneficial Use Wetland Creation Sites in the Sabine National Wildlife Refuge for Use in Restoration Trajectory Development

PURPOSE: The development of regional restoration trajectories of marsh creation and nourishment projects is key to improved design, management, and implementation of adaptive management principles. Synthesizing information from multiple marsh creation projects constructed at various times but with consistent site characteristics and borrow material sources, helps elucidate restoration success in a specific region. Specifically, this technical note (TN) documents the process of determining a suitable study area, construction methods, and the current state of establishing sites in the Louisiana Gulf Coast that could be used for restoration trajectory development. This investigation compiled information from the construction phases, Landset 8 satellite imagery, and the most recent digital elevation model (DEM) to investigate elevation and vegetation establishment within these sites.

27 Sep 2022

Analytic Methods for Establishing Restoration Trajectories

Abstract: This special report identifies metrics (standard and novel) and analytic approaches to developing trajectories and then describes the conceptual process of using those metrics and approaches to develop restoration trajectories to inform adaptive management in salt-marsh systems. We identify the composite time series trajectory (CTST) approach, in which metrics are measured from restoration sites of different ages within a small spatial range, and the retrospective single-site trajectory (RSST) approach, in which the same restoration metrics are measured over time at one restoration site. In all, we assessed the metrics of 39 studies of salt-marsh restoration in the United States between 1991 and 2019.

27 Jan 2020

PUBLICATION NOTICE: Evaluation of Iron Sulfide Soil Formation Following Coastal Marsh Restoration – Observations from Three Case Studies

 Link: http://dx.doi.org/10.21079/11681/35275 Report Number: ERDC/EL TR-20-1Title: Evaluation of Iron Sulfide Soil Formation Following Coastal Marsh Restoration – Observations from Three Case StudiesBy Jacob F. Berkowitz, and Christine M. VanZomeren Approved for Public Release; Distribution is Unlimited January 2020 Abstract: Wetland restoration