28 Nov 2023

Total Water Level Controls on the Trajectory of Dune Toe Retreat

Abstract: This study examines the trajectory (slope) of coastal foredune toe retreat in response to nine storm events that impacted the Outer Banks, North Carolina, USA. High resolution, three-dimensional, repeat mobile terrestrial lidar observations over a four kilometer stretch of coast were used to assess spatiotemporal beach and dune evolution at the storm timescale. Consistent with existing field observations from other sandy coastlines, an upward toe retreat was observed for most instances of dune retreat in the Outer Banks. However, these new topographic data indicate that the retreat can proceed steeply downward when the maximum total water level (TWL) defined by the 2% runup exceedance level is not high enough, for long enough, to erode the dune face. Non-linear relationships were found between the dune toe retreat trajectory as well as both the magnitude and duration of TWL above the dune toe, where instances of upward- and downward-directed retreat are best differentiated using the 7% runup exceedance level, rather than the commonly used 2% level. This physically justified non-linear relationship is shown to be consistent with observations from other studies, and could be a more effective parameterization for the retreat trajectory than those currently implemented in wave-impact dune erosion models.

17 Nov 2023

Advancing Engineering With Nature Initiatives in Point Hope, Alaska

Purpose: Growing environmental risk threatens communities in cold regions, particularly as climate change contributes to permafrost thaw, a reduction in sea-ice extent, and some of the largest rates of coastal erosion on earth. In the context of these significant and growing risks, the Engineering With Nature® (EWN®) program formed its cold regions work unit in 2021 to explore the potential to apply EWN approaches in these areas to mitigate environmental risk while supporting resilient outcomes. The work unit’s objectives include working with communities to preserve the natural environment and traditions, advancing the work unit’s understanding of cold-region environments, and providing guidance on the implementation of natural and nature-based features (NNBF) and EWN in cold regions to increase resilience. This technical note (TN) provides an overview of the EWN in cold regions technical approach as applied to Point Hope, Alaska, which includes community engagement, the integration of traditional ecological knowledge (TEK) throughout the project, and the development of cold-regions-specific knowledge and tools.

6 Nov 2023

A Method for Evaluating Automatic Identification System (AIS) Coverage on Select Inland Waterways in 2020 and 2021: Upper Mississippi River, Illinois River, and Ohio River

Abstract: The Automatic Identification System (AIS) shares vessel position information for navigational safety purposes. AIS broadcasts are received by other ships and terrestrial stations; however, in some areas there is no, or low, terrestrial station coverage to receive broadcasts. The US Army Corps of Engineers (USACE) developed an Online Travel Time Atlas (OTTA) to process AIS data and derive a transit count. This study examined OTTA output from 2020 and 2021 to identify areas of high or low AIS coverage along the Upper Mississippi, Illinois, and Ohio Rivers. Segments with a yearly average of two or more transit per day were classified as high coverage, those with less than a yearly average of two transits per day were classified as low coverage. Rivers were segmented using the USACE National Channel Framework reach boundaries. Results based on calculated vessel transits were as follows: Upper Mississippi River: 837.4 miles (98%) had high coverage, with 17.4 miles (2%) of low coverage; Illinois River: 190.5 miles (59%) had high AIS coverage, and 133 miles (41%) had low AIS coverage; Ohio River: 644 miles (66%) had high coverage, and 337 miles (34%) had low coverage. AIS coverage could be improved by raising antennae heights, installing repeater equipment, or adding towers.

23 Oct 2023

Considering Sediment Beneficial Use Options at Lake Michigan Harbors in Wisconsin

Abstract: In 2020 the US Army Corps of Engineers (USACE) reassigned 14 federally maintained harbors in the Wisconsin waters of Lake Michigan to USACE–Chicago District. The administrative change presents opportunities for in-creased beneficial use of sediment at harbors that have not traditionally placed sediment beneficially. This paper summarizes a screening-level analysis of 12 harbors to determine which harbors are likely to have sediment appropriate for beneficial use in the future, either in water or upland. The harbors were qualitatively ranked according to the potential for future successful beneficial use of navigationally dredged sediment. Using this screening, data needs were defined and next steps to aid the development of a regional dredged-material management plan were identified.

20 Oct 2023

DataSwitch Data Sweeper (DS)2

Purpose: The purpose of this Coastal and Hydraulics Engineering technical note (CHETN) is to specify the software requirements, architecture, and detailed design for the DataSwitch Data Sweeper (DS)² application. This document is designed for the software developers maintaining (DS)² and is intended to aid these developers in understanding its architecture and underlying functionality.

4 Oct 2023

Full-Scale Trafficability Testing of Prototype Submersible Matting Systems

Abstract: This report describes the full-scale evaluation of prototype submersible matting systems (SUBMAT) at a test site at the US Army Engineer Research and Development Center’s Vicksburg, Mississippi, site. The SUBMAT prototypes were designed to bridge the gap between high and low tide at a beach interface to enable 24-hour operation at an expeditionary watercraft landing site. This phase of the SUBMAT prototype development was intended to determine prototype system durability by applying military vehicle loads representing a combat brigade insertion across a littoral zone. The two mat systems evaluated in this study were the PYRACELL Road Building System (PRBS) and a basaltic rebar mat system. The results of the study showed that the PRBS system was able to sustain 1,000 Medium Tactical Vehicle Replacement, 350 Heavy Expanded Mobility Tactical Truck, and over 150 M1A1 main battle tank passes without significant damage. The basaltic rebar mat failed early in the test and was removed from further consideration for the SUBMAT application. Observations and lessons learned from this phase of the prototype PRBS development will be used to improve the PRBS design and modify its installation procedures for improved efficiency.

18 Sep 2023

A Resilient Path Forward for the Marine Transportation System: Recommendations for Response and Recovery Operations from the 2017-2019 Hurricane Seasons

Abstract: The Marine Transportation System (MTS), Resilience Integrated Action Team (RIAT), is tasked by the coordinating board of the US Committee on the MTS to serve as a coordinating body to identify the impacts, best practices, and lessons learned by federal agencies involved in the response and recovery of the MTS after hurricane seasons. In response to this request, the RIAT has focused its analysis on the ability of MTS federal agencies to prepare, respond, recover, and adapt to as well as from disruptions. This was accomplished through workshops focused on gathering the collective experiences of emergency response professionals. In 2017, recommendations were gathered based on experiences responding to Hurricanes Harvey, Irma, and Maria. In this report, a similar approach was adopted to gather findings from Hurricanes Florence and Michael in 2018 and Hurricane Dorian in 2019. Utilizing the successes, challenges, and best practices from all six of these storms, the RIAT identified key coordinating bodies and the participants for each and key takeaways relative to the coordination of agencies with respect to the four steps of resilience: prepare, absorb, recover, and adapt.

15 Sep 2023

Real-Time Forecasting Model Development Work Plan

Abstract: The objective of the Lowermost Mississippi River Management Program is to move the nation toward more holistic management of the lower reaches of the Mississippi River through the development and use of a science-based decision-making framework. There has been substantial investment in the last decade to develop multidimensional numerical models to evaluate the Lowermost Mississippi River (LMMR) hydrodynamics, sediment transport, and salinity dynamics. The focus of this work plan is to leverage the existing scientific knowledge and models to improve holistic management of the LMMR. Specifically, this work plan proposes the development of a real-time forecasting (RTF) system for water, sediment, and selected nutrients in the LMMR. The RTF system will help inform and guide the decision-making process for operating flood-control and sediment-diversion structures. This work plan describes the primary components of the RTF system and their interactions. The work plan includes descriptions of the existing tools and numerical models that could be leveraged to develop this system together with a brief inventory of existing real-time data that could be used to validate the RTF system. A description of the tasks that would be required to develop and set up the RTF system is included together with an associated timeline.

14 Sep 2023

Surge Analysis in Mobile Harbor, Alabama: Ship-Simulation Report

Abstract: A navigation channel improvement study for Mobile Harbor was conducted by the US Army Corps of Engineers, Mobile District (CESAM), and the Alabama State Port Authority. The US Army Engineer Research and Development Center (ERDC) assisted CESAM in assessing channel modifications using ERDC’s Ship/Tow Simulator through a Feasibility Level Screening Simulation study in 2017 and through a more comprehensive ship-simulation study in 2020. During the 2020 study, a safety concern was identified related to vessel interactions between a transiting vessel passing docked vessels at the McDuffie Coal Terminal located along the main federal channel. In the previous ship-simulation studies, the docked vessels were represented as targets, which means the ships are visually represented but no hydrodynamic interaction is captured. To fully assess this interaction, a surge-analysis study was completed in 2022 that used hydrodynamic models to represent docked vessels with representative mooring conditions. This study assessed several proposed navigation channel expansions across from the McDuffie Coal Terminal over the course of six testing days with four pilots. Assessment of the proposed modifications was accomplished through analysis of ship simulations completed by experienced local pilots, track plots, run sheets, and final pilot questionnaires.

13 Sep 2023

Sensitivity of Sediment Transport Analyses in Dam Removal Applications

Abstract: Dam removal has become a widespread river management practice in the US for a variety of goals including ecosystem restoration, removing aging infrastructure, flood risk management, and recreation. The ability to forecast the sediment impacts of dam removal is critical to evaluating different management alternatives that can minimize adverse consequences for ecosystems and human communities. Tullos et al. (2016) identified seven Common Management Concerns (CMCs) associated with dam removal. Four of these CMCs; degree and rate of reservoir sediment erosion, excessive channel incision upstream of reservoirs, downstream sediment aggradation, and elevated downstream turbidity are associated with stored sediment release and changing fluvial hydraulics. There are a range of existing qualitative and quantitative tools developed to infer or quantify geomorphic implications of disturbances like these in river environments (McKay et al. 2019). This study investigated how a one-dimensional (1D) sediment transport model can inform these four CMCs, develop an approach for assessing sediment transport model sensitivity in the context of the Simkins Dam removal, and use sensitivity analyses to identify key uncertainties, which can inform data collection and model building for other dam removal projects. For the selected case study, model outputs including the mean effective invert change (MEIC) and eroded sediment volume from reservoir were highly sensitive to the variation of the reservoir sediment gradation and sorting method selection. These model outputs also showed some sensitivity to the selected transport functions. Erosion method sensitivity using the channel evolution method will vary depending on side slope and channel parameter selection.