14 Sep 2022

Is Mean Discharge Meaningless for Environmental Flow Management?

PURPOSE: River ecosystems are highly dependent on and responsive to hydrologic variability over multiple time scales (e.g., hours, months, years). Fluctuating river flows present a key challenge to river managers, who must weigh competing demands for freshwater. Environmental flow recommendations and regulations seek to provide management targets balancing socio-economic outcomes with maintenance of ecological integrity. Often, flow management targets are based on average river conditions over temporal windows such as days, months, or years. Here, three case studies of hydrologic variability are presented at each time scale, which demonstrate the potential pitfalls of mean-based environmental flow criteria. Each case study shows that the intent of the environmental flow target is not met when hydrologic variability is considered. While mean discharge is inadequate as a single-minded flow management target, the consequences of mean flow prescriptions can be avoided in environmental flow recommendations. Based on these case studies, a temporal hierarchy of environmental flow thresholds is proposed (e.g., an instantaneous flow target coupled with daily and monthly averages), which would improve the efficacy of these regulations.

14 Sep 2022

Ecological Model Development: Evaluation of System Quality

PURPOSE: Ecological models are used throughout the US Army Corps of Engineers (USACE) to inform decisions related to ecosystem restoration, water operations, environmental impact assessment, environmental mitigation, and other topics. Ecological models are typically developed in phases of conceptualization, quantification, evaluation, application, and communication. Evaluation is a process for assessing the technical quality, reliability, and ecological basis of a model and includes techniques such as calibration, verification, validation, and review. In this technical note (TN), we describe an approach for evaluating system quality, which generally includes the computational integrity, numerical accuracy, and programming of a model or modeling system. Methods are presented for avoiding computational errors during development, detecting errors through model testing, and updating models based on review and use. A formal structure is proposed for model test plans and subsequently demonstrated for a hypothetical habitat suitability model. Overall, this TN provides ecological modeling practitioners with a rapid guide for evaluating system quality.

6 Sep 2022

Coastal Resilience: Benefits of Wrack and Dune Systems and Current Management Practices

Purpose: The purpose of this US Army Engineer Research and Development Center (ERDC) technical note (TN) is to review both the ecological and geomorphological impacts of wrack on dune systems and provide an overview of current beach dune and wrack management practices. As part of the US Army Corps Regional Sediment Management (RSM) Program, this TN also introduces a case study investigating wrack management solutions for dune stabilization.

29 Aug 2022

Remote Sensing Capabilities to Support EWN® Projects: An R&D Approach to Improve Project Efficiencies and Quantify Performance

PURPOSE: Engineering With Nature (EWN®) is a US Army Corps of Engineers (USACE) Initiative and Program that promotes more sustainable practices for delivering economic, environmental, and social benefits through collaborative processes. As the number and variety of EWN® projects continue to grow and evolve, there is an increasing opportunity to improve how to quantify their benefits and communicate them to the public. Recent advancements in remote sensing technologies are significant for EWN® because they can provide project-relevant detail across a large areal extent, in which traditional survey methods may be complex due to site access limitations. These technologies encompass a suite of spatial and temporal data collection and processing techniques used to characterize Earth's surface properties and conditions that would otherwise be difficult to assess. This document aims to describe the general underpinnings and utility of remote sensing technologies and applications for use: (1) in specific phases of the EWN® project life cycle; (2) with specific EWN® project types; and (3) in the quantification and assessment of project implementation, performance, and benefits.

18 Aug 2022

Geospatial Suitability Indices (GSI) Toolbox: User’s Guide

Abstract: Habitat suitability models have been widely adopted in ecosystem management and restoration to assess environmental impacts and benefits according to the quantity and quality of a given habitat. Many spatially distributed ecological processes require application of suitability models within a geographic information system (GIS). This technical report presents a geospatial toolbox for assessing habitat suitability. The geospatial suitability indices (GSI) toolbox was developed in ArcGIS Pro 2.7 using the Python 3.7 programming language and is available for use on the local desktop in the Windows 10 environment. Two main tools comprise the GSI toolbox. First, the suitability index (SIC) calculator tool uses thematic or continuous geospatial raster layers to calculate parameter suitability indices using user-specified habitat relationships. Second, the overall suitability index calculator (OSIC) combines multiple parameter suitability indices into one overarching index using one or more options, including arithmetic mean, weighted arithmetic mean, geometric mean, and minimum limiting factor. The result is a raster layer representing habitat suitability values from 0.0–1.0, where zero (0) is unsuitable habitat and one (1) is ideal suitability. This report documents the model purpose and development and provides a user’s guide for the GSI toolbox.

11 Aug 2022

Environmental Evaluation and Management of Dredged Material for Beneficial Use: A Regional Beneficial Use Testing Manual for the Great Lakes

Abstract: The Environmental Evaluation and Management of Dredged Material for Beneficial Use: A Regional Beneficial Use Testing Manual for the Great Lakes (a.k.a. Great Lakes Beneficial Use Testing Manual) is a resource document providing technical guidance for evaluating the suitability of dredged sediment for beneficial use in aquatic and terrestrial environments in the Great Lakes region. The procedures in this manual are based on the Environmental Laboratory extensive research, working with US Army Corps of Engineers (USACE) Great Lakes districts, state resource agencies, and local stakeholders seeking to develop dredged material beneficial use alternatives consistent with regional needs and goals. This manual is the first guidance document developed by USACE for evaluating the environmental suitability of dredged material specifically for beneficial use placements. It provides a tiered framework for evaluating the environmental suitability of aquatic and upland beneficial uses consistent with the Inland Testing Manual and the Upland Testing Manual. This manual is intended to serve as a regional platform to increase collaborative problem-solving and endorse a common understanding of the scientific and institutional practices for evaluating dredged material for any beneficial use. Dredged sediment may be managed as a valuable resource, with great potential to create economic, environmental, and social benefits.

11 Aug 2022

Realizing Multiple Benefits in a Southeast Louisiana Urban Flood Control Project through Application of Engineering With Nature® Principles

PURPOSE: The application of Engineering With Nature® (EWN®) principles in urban environments and watersheds within and outside the US Army Corps of Engineers (USACE) is increasing. Extreme rainfall events have triggered the need and development of more sustainable urban infrastructure in urban areas such as New Orleans, Louisiana. This technical note documents a USACE–New Orleans District (MVN) project that successfully applied EWN principles in an urban landscape to reduce flood risk while providing other environmental, social, economic, and engineering benefits to both the community and the environment.

11 Aug 2022

Oyster Reef Connectivity: Ecological Benefits and Associated Vulnerabilities

OVERVIEW: Global oyster abundance has declined ~85 % over the past 200 years, primarily because of overharvesting (Beck, Brumbaugh, and Airoldi 2011; Kirby 2004). Healthy oyster reef systems benefit the environment in many ways, including water-quality improvement, shoreline protection, increased biological and habitat diversity, and carbon sequestration. To maintain these environmental benefits, reef-restoration efforts that produce healthy, sustainable oyster reefs are essential. To this end, the US Army Corps of Engineers (USACE) has been involved in reef-restoration projects in many locations, including extensive efforts in the Chesapeake Bay (Virginia, Maryland), coastal regions of New York and New Jersey, and the Gulf of Mexico.

21 Jul 2022

Implementing Endangered Species Act (ESA) Section 7 (a)(1) Conservation Planning During US Army Corps of Engineers (USACE) Coastal Engineering

Purpose: This technical note was developed by the US Army Engineer Research and Development Center–Environmental Laboratory (ERDC-EL) to provide guidance to the US Army Corps of Engineers (USACE) on implementing Endangered Species Act* (ESA) Section 7(a)(1) conservation planning, in coordination with the US Fish and Wildlife Service (USFWS) and the National Marine Fisheries Service (NMFS) during coastal engineering projects. USACE expends ~$200–$300 million each year on compliance, conservation, and other activities associated with the ESA (USACE 2022), and these expenditures often exceed those of other federal agencies (for example, US Bureau of Land Management) that have jurisdiction over far greater land holdings than USACE. To streamline the ESA compliance process, lower costs, and generate more positive outcomes for federally listed threatened and endangered species (TES), USACE was directed in June 2015 by the Deputy Commanding General (DCG) for Civil and Emergency Operations to proactively identify and incorporate conservation benefits into all projects when and where opportunities arise, under the authority of Section 7(a)(1) of the ESA (USACE 2015). The DCG identified Section 7(a)(1) conservation planning as a mechanism to efficiently achieve project purposes, create environmental value, and streamline the ESA Section 7(a)(2) consultation process

18 Apr 2022

Sustainable Harmful Algal Bloom Mitigation by 3D Printed Photocatalytic Oxidation Devices (3D-PODs)

Abstract: The impacts of Harmful Algal Blooms (HAB), often caused by cyanobacteria (Figure 1), on water resources are increasing. Innovative solutions for treatment of HABs and their associated toxins are needed to mitigate these impacts and decrease risks without introducing persistent legacy contaminants that cause collateral ecosystem impacts. This technical note (TN) identifies novel opportunities enabled by Additive Manufacturing (AM), or 3D printing, to produce high surface area advanced material composites to rapidly prototype sustainable environmental solutions for aquatic nuisance species control. This innovative research explores deployment of 3D-printable polymer composite structures containing nano-scale photocatalysts for targeted open water treatment of HABs that are customizable to the site-of-concern and also retrievable, reusable, and sustainable. The approach developed to control cyanobacteria HAB events has the potential to augment or replace broadcast, non-specific chemical controls that otherwise put non-target species and ecological resources at long-term risk. It can also augment existing UV-treatment HAB treatment control measures. The expected research outcome is a novel, effective, and sustainable HAB management tool for the US Army Corps of Engineers (USACE) and resource managers to deploy in their HAB rapid response programs. The research will provide a framework for scale-up into other manufacturing methods (e.g., injection molding) to produce the devices in bulk (quickly and efficiently). Research for this project title “Mitigation of Harmful Algal Bloom Toxins using 3D Printed Photocatalytic Materials (FY21-23)” was sponsored by the US Army Engineer Research Development Center’s (ERDC) Aquatic Nuisance Species Research Program (ANSRP).