9 Jan 2025

National Ordinary High Water Mark Field Delineation Manual for Rivers and Streams: Final Version

Abstract: The ordinary high water mark (OHWM) defines the lateral extent of non-tidal aquatic features in the absence of adjacent wetlands in the United States. The federal regulatory definition of the OHWM, 33 CFR 328.3(c)(4), states the OHWM is “that line on the shore established by the fluctuations of water and indicated by physical characteristics such as [a] clear, natural line impressed on the bank, shelving, changes in the character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that consider the characteristics of the surrounding areas.” This is the first manual to present a methodology for nationwide identification and delineation of the OHWM. A two-page data sheet and field procedure outline a weight-of-evidence (WOE) methodology to organize and evaluate observations at stream sites. This manual presents a consistent, science-based method for delineating the OHWM in streams. It also describes regional differences and challenges in identifying the OHWM at sites disturbed by human-induced or natural changes and illustrates how to use remote data to structure field inquiries and interpret field evidence using the principles of fluvial science. The manual demonstrates that, in many landscape settings, the OHWM may be located near the bankfull elevation.

2 Jan 2025

Assessing the Validity and Accuracy of Wetland Indicator Status Ratings for Eight Species in Alaska Subregions

Abstract: Preexisting ecological information and plant species occurrence data were used to determine the accuracy and validity of the present regional and subregional wetland indicator status ratings for eight species: Andromeda polifolia, Arctous rubra, Carex canescens, Rhododendron tomentosum, Rubus arcticus, Salix arctica, Salix pulchra, and Viola palustris. Technical documentation was developed to either (1) support the current National Wetland Plant List (NWPL) subregion boundaries and wetland indicator status ratings for the NWPL Alaska Region or (2) support a proposed change to the subregions or wetland indicator status ratings for the NWPL Alaska Region, for inclusion into the next NWPL update. The project developed repeatable, quantitative methods for assignment of wetland indicator status rating. Analyses included multiple correspondence analysis (MCA), analysis of similarities (ANOSIM), nonmetric multidimensional scaling (NMDS), and principal component analysis (PCA). Prevalence index (PI) was used as a numeric approximation of wetland status for comparing observations across subregions. A pilot study on S. pulchra data evaluated regional assignments by machine learning and assessed the feasibility of correlation network analysis and Louvain clustering for wetland indicator status rating assignment as dictated by co-occurring species. The methods developed for this Alaska-specific study may be applied to any future regional or subregional updates to the NWPL.

15 Oct 2024

Vegetation Establishment and Management in USACE Floodwater Detention Basins: Greens Bayou Flood Risk Management Mitigation Project

Abstract: This report documents efforts by the US Army Engineer Research and Development Center (ERDC) in assisting the US Army Corps of Engineers (USACE) Galveston District (SWG) in native vegetation establishment design, propagation, installation, monitoring, and adap-tive management for the mitigation requirements of the Greens Bayou Flood Risk Management Project. Specifically, to provide (1) a vegetation establishment design ensuring development of sustainable native plant communities compatible with flooding and drought events; (2) suitable native aquatic, wetland, and woody plants for project use; (3) implementation of plantings; (4) monitoring and adaptive management; and (5) vegetation establishment reports and an operations and maintenance manual for long-term vegetation management of the project site. The Greens Bayou Project included approximately 3.7 miles of channel conveyance improvements and 138 acres of storm-water basin detention storage to reduce flooding damage by safely storing excess stormwater during heavy rain events and slowly releasing it back into the bayou. The completed basin was designed to hold approximately 1,400 acre-ft, or 538 million gal., of stormwater. Vegetation establishment, monitoring, and adaptive management efforts in the mitigation features discussed herein occurred between 2019 and 2023.

22 Dec 2022

National Ordinary High Water Mark Field Delineation Manual for Rivers and Streams : Interim Version

Abstract: The ordinary high water mark (OHWM) defines the lateral extent of nontidal aquatic features in the absence of adjacent wetlands in the United States. The federal regulatory definition of the OHWM, 33 CFR 328.3(c)(7), states the OHWM is “that line on the shore established by the fluctuations of water and indicated by physical characteristics such as [a] clear, natural line impressed on the bank, shelving, changes in the character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that consider the characteristics of the surrounding areas.” This is the first manual to present a methodology for nationwide identification and delineation of the OHWM. A two-page data sheet and field procedure outline a weight-of-evidence (WoE) methodology to organize and evaluate observations at stream sites. This manual presents a consistent, science-based method for delineating the OHWM in streams. It also describes regional differences and challenges in identifying the OHWM at sites disturbed by human-induced or natural changes and illustrates how to use remote data to structure field inquiries and interpret field evidence using the principles of fluvial science. The manual demonstrates that, in many landscape settings, the OHWM may be located near the bankfull elevation.

29 Nov 2022

National Ordinary High Water Mark Field Delineation Manual for Rivers and Streams : Interim Version

Abstract: The ordinary high water mark (OHWM) defines the lateral extent of nontidal aquatic features in the absence of adjacent wetlands in the United States. The federal regulatory definition of the OHWM, 33 CFR 328.3(c)(7), states the OHWM is “that line on the shore established by the fluctuations of water and indicated by physical characteristics such as [a] clear, natural line impressed on the bank, shelving, changes in the character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that consider the characteristics of the surrounding areas.” This is the first manual to present a methodology for nationwide identification and delineation of the OHWM. A two-page data sheet and field procedure outline a weight-of-evidence (WoE) methodology to organize and evaluate observations at stream sites. This manual presents a consistent, science-based method for delineating the OHWM in streams. It also describes regional differences and challenges in identifying the OHWM at sites disturbed by human-induced or natural changes and illustrates how to use remote data to structure field inquiries and interpret field evidence using the principles of fluvial science. The manual demonstrates that, in many landscape settings, the OHWM may be located near the bankfull elevation.

5 Oct 2021

Evaluating Drone Truthing as an Alternative to Ground Truthing: An Example with Wetland Plant Identification

Purpose: Satellite remote sensing of wetlands provides many advantages to traditional monitoring and mapping methods. However, remote sensing often remains reliant on labor- and resource- intensive ground truth data for wetland vegetation identification through image classification training and accuracy assessments. Therefore, this study sought to evaluate the use of unmanned aircraft system (UAS) data as an alternative or supplement to traditional ground truthing techniques in support of remote sensing for identifying and mapping wetland vegetation.