8 Mar 2023

A Large-Scale Community Storm Processes Field Experiment: The During Nearshore Event Experiment (DUNEX) Overview Reference Report

Abstract: The DUring Nearshore Event EXperiment (DUNEX) was a series of large-scale nearshore coastal field experiments focused on during-storm, nearshore coastal processes. The experiments were conducted on the North Carolina coast by a multidisciplinary group of over 30 research scientists from 2019 to 2021. The overarching goal of DUNEX was to collaboratively gather information to improve understanding of the interactions of coastal water levels, waves, and flows, beach and dune evolution, soil behavior, vegetation, and groundwater during major coastal storms that affect infrastructure, habitats, and communities. In the short term, these high-quality field measurements will lead to better understanding of during-storm processes, impacts and post-storm recovery and will enhance US academic coastal research programs. Longer-term, DUNEX data and outcomes will improve understanding and prediction of extreme event physical processes and impacts, validate coastal processes numerical models, and improve coastal resilience strategies and communication methods for coastal communities impacted by storms. This report focuses on the planning and preparation required to conduct a large-scale field experiment, the collaboration amongst researchers, and lessons learned. The value of a large-scale experiment focused on storm processes and impacts begins with the scientific gains from the data collected, which will be available and used for decades to come.

23 Feb 2023

AIS Data: An Overview of Free Sources

Abstract: The purpose of this Coastal and Hydraulics Engineering technical note (CHETN) is to describe the sources of Automatic Identification System (AIS) data available to the public, with a focus on federal employees who may need AIS data to carry out their official duties. AIS data, in this context, refer to both real-time and historic vessel position information.

13 Feb 2023

Sustainable Sediment Management at US Army Corps of Engineers Reservoirs

Abstract: The US Army Corps of Engineers (USACE) maintains and operates 419 reservoirs nationwide for diverse purposes. This infrastructure is essential to the nation’s continued economic progress and provides numerous benefits. Sedimentation in reservoirs causes the loss of storage capacity, leading to interference with operations, reduction of project benefits, and can eventually render project operation technically infeasible or uneconomical. All reservoirs trap sediment, and sustainable long-term operation can be achieved only if sedimentation is managed. With many of the USACE reservoirs now reaching 50 years of age, sedimentation is starting to encroach on the beneficial pools. Under the paradigm of sustainable use, it is important to identify and implement strategies to sustain reservoir operation in the long term, beyond the period contemplated in the original project design life. This report outlines the major types of sediment management strategies available for reservoirs. Because the rate of new reservoir construction by USACE is very low, this report focuses on remedial strategies at existing reservoirs and presents a general methodology for the preliminary analysis of such sites. This report examines four example USACE reservoirs with known sedimentation issues to highlight the types of problems encountered and the development of strategies that can lead to sustainable use.

7 Feb 2023

Remote Sensing Tools to Support Ordinary High Water Mark Delineation

Abstract: This document is a technical note (TN) that describes existing and recently developed tools to support ordinary high water mark (OHWM) identification and delineation. It also presents a case study to demonstrate how utilizing the tools provide supporting lines of evidence in OHWM delineations.

6 Feb 2023

Establishing a Series of Dust Event Case Studies for North Africa

Abstract: Dust aerosols often create hazardous air quality conditions that affect human health, visibility, agriculture, and communication in various parts of the world. While substantial progress has been made in dust-event simulation and hazard mitigation over the last several decades, accurately forecasting the spatial and temporal variability of dust emissions continues to be a challenge. This report documents an analysis of atmospheric conditions for a series of dust events in North Africa. The researchers highlight four analyzed events that occurred between January 2016 to present in the following locations: (1) the western Sahara Desert; (2) East Algeria and the Iberian Peninsula; (3) Chad-Bodélé Depression; (4) Algeria and Morocco. For each event, the researchers developed an overview of the general synoptic, mesoscale, and local environmental forcing conditions that controlled the event evolution and used a combination of available lidar data, surface weather observations, upper-air soundings, aerosol optical depth, and satellite imagery to characterize the dust conditions. These assessments will support downstream forecast model evaluation and sensitivity testing; however, the researchers also encourage broader use of these assessments as reference case studies for dust transport, air quality modeling, remote sensing, soil erosion, and land management research applications.

17 Jan 2023

US Port Connectivity and Ramifications for Maintenance of South Atlantic Division Ports

Abstract: This study utilized automatic identification system (AIS) data to quantify vessel traffic patterns within a predominantly US port network from 1 January 2009 to 31 December 2020, with the methods validated using independent data sets collected between 1 January 2015 and 31 December 2019. The analysis focused on South Atlantic Division (SAD) ports. AIS-derived data characterized individual ports’ traffic and port-to-port connectivity for the network. With foreign vessel entrances and clearances (E&C) data, the AIS-reported vessel characteristics enabled calculation of ships’ physical volume, which was a reasonable proxy for tonnage at many SAD ports. The PageRank algorithm was then applied to port-to-port traffic, revealing how individual ports participate in cargo movement through the network. PageRank scores also provided insight into the maritime supply chain beyond traditional traffic metrics. For example, many East Coast SAD ports ranked higher by PageRank than by raw tonnage. Because of the supply chain implications of shared vessel traffic, PageRank scores can augment tonnage metrics when prioritizing channel and infrastructure maintenance. Vessel volume, port-to-port connectivity, and PageRank scores reveal maritime supply chain resilience by identifying alternative destinations for cargo bound for disrupted ports, robustness across supply chains, and the effects of seasonality and disruptions.

10 Jan 2023

Strength and Toughness Inputs to Fitness for Service Analysis of Existing Hydraulic Steel Structures

Abstract: The purpose of this effort is to describe a database containing information about the strength and toughness of steel used in existing hydraulic steel structures (HSS). The lack of information about these properties often presents a barrier to conducting fitness for service (FFS) analysis. The statistical dependence between strength and toughness variables and other database fields is evaluated to assess their potential as predictive variables.

8 Dec 2022

Coastal Hazards System–Puerto Rico and US Virgin Islands (CHS-PR)

Abstract: The South Atlantic Coastal Study (SACS) was completed by the US Army Corps of Engineers to quantify storm surge and wave hazards allowing for the expansion of the Coastal Hazards System (CHS) to the South Atlantic Division (SAD) domain. The goal of the CHS-SACS was to quantify coastal storm hazards for present conditions and future sea level rise (SLR) scenarios to aid in reducing flooding risk and increasing resiliency in coastal environments. CHS-SACS was completed for three regions within the SAD domain, and this report focuses on the Coastal Hazards System–Puerto Rico and US Virgin Islands (CHS-PR). This study applied the CHS Probabilistic Coastal Hazard Analysis (PCHA) framework for quantifying tropical cyclone (TC) responses, leveraging new atmospheric and hydrodynamic numerical model simulations of synthetic TCs developed explicitly for the CHS-PR region. This report focuses on documenting the PCHA conducted for CHS-PR, including the characterization of storm climate, storm sampling, storm recurrence rate estimation, marginal distributions, correlation and dependence structure of TC atmospheric-forcing parameters, development of augmented storm suites, and assignment of discrete storm weights to the synthetic TCs. As part of CHS-PR, coastal hazards were estimated for annual exceedance frequencies over the range of 10 yr⁻¹ to 10⁻⁴ yr⁻¹.

1 Dec 2022

Evaluation of Cedar Tree Revetments for Bank Stabilization at the Locust Creek Conservation Area, Missouri: Quantifying Bank Erosion Volumes from Preproject to Postfailure

Abstract: The US Army Corps of Engineers Regional Sediment Management (RSM) program funded research to assess the longevity and effectiveness of cedar tree revetments for sediment reduction. Between 1988 and 1997, the Missouri Department of Conservation (MDC) constructed multiple cedar tree revetments, plantings, and a grade-control structure at an experimental stream management area on Locust Creek within the Locust Creek Conservation Area (LCCA). For the first few years, MDC also replaced missing trees as needed. MDC monitored these sites with photographs and cross sections until 2004. This study evaluated bank stability on Locust Creek from 1970 to 2019 using aerial imagery, lidar, ground surveys, and a December 2019 site visit to estimate the areal change in streambanks and the volume of sediment eroded over the years. Based on their dates of construction, the project compared preproject, with-project, and postfailure conditions at each site. The project included cedar tree revetments, other hardwood revetments, plantings, and a grade-control structure. This research found a 50% to 64% reduction in erosion for approximately 14 years. As of December 2019, all tree revetments had failed, and banks were bare and steep. The grade-control structure remained intact and continued to stabilize bed and banks immediately upstream.

1 Dec 2022

A Review of Tidal Embayment Shoaling Mechanisms in the Context of Future Wetland Placement

Abstract: Wetland construction in tidally influenced embayments is a strategy for beneficial use of sediment dredged from nearby navigation channels. These projects have the potential to alter basin morphology, tidal hydrodynamics, and shoaling trends. This special report provides a broad review of the literature related to engineering-induced changes in tidal range, salinity, tidal prism, tidal asymmetry, and other known causes of shoaling. Each potential shoaling mechanism is then evaluated in the context of wetland placement to provide a foundation for future beneficial use research. Based on a compilation of worldwide examples, wetland placement may reduce tidal amplitude and enhance ebb current dominance, thus reducing shoaling rates in the channels. However, constructed wetlands could also reduce the embayment’s tidal prism and cause accelerated shoaling relative to the pre-engineered rate. Because constructed wetlands are often created in conjunction with navigation channel dredging, the system’s morphologic response to wetland construction is likely to be superimposed upon its response to channel deepening, and the net effect may vary depending on a variety of system- specific parameters. Planning for future wetland placements should include an evaluation of local hydrodynamic behavior considering these factors to predict site-specific response.