6 Aug 2024

Tools and Technical Guidelines for Delineating the Extent of Tidal Waters: Proof of Concept

Abstract: The delineation of shorelines in tidally influenced waters, as well as the inland extent of tidal influence of those waters, is often used to define the extent of federal and/or state jurisdictional boundaries, including the US Army Corps of Engineers’ (USACE) limits of jurisdiction under the Rivers and Harbors Act of 1899 (RHA) and Section 404 of the Clean Water Act. At present, USACE and other practitioners use a variety of field observations and desktop-based data sets, tools, and techniques to identify and delineate the lateral and longitudinal extent of USACE’s jurisdiction under the RHA for tidally influenced waters. Tidal waters, and thus federal jurisdiction under the RHA, “end where the rise and fall of the water surface can no longer be practically measured in a predictable rhythm.” However, the technical standards, definitions, and data to delineate tidal extent are also lacking. The uncertainty and ambiguity in what constitute tidal extent increases litigation risk and decreases repeatability and technical defensibility of USACE decisions. Nationally applicable technical guidance and rapid tools and techniques are needed to increase defensibility and consistency across all coastal USACE districts while also accelerating USACE Regulatory decision-making.

5 Aug 2024

Analysis of Beach Cusp Formation and Evolution Using High-Frequency 3D Lidar Scans

Abstract: Beach cusp characteristics were explored using 15 months of 3D lidar scans collected hourly at the Duck, NC, Field Research Facility. Fourier analyses performed on lidar-derived beach elevation contours generated spatial cusp spectra. Active cusp events identified from the location and magnitude of each spectrum’s peak were used to evaluate conditions during cusp formation and evolution. Cusps primarily developed during normally-incident, long-period, low-energy wave conditions with low frequency spread and reflective beach conditions. Often, however, persistent upper-beach cusps lasted days to months and dynamic lower-beach cusps evolved over individual tidal cycles. At times, beaches exhibiting multiple cusp systems reverted to a single cusp system extending the entire beach when the high-tide waterline reached the upper-beach cusps, with the location and spacing of the resulting lower-beach cusps controlled by the upper-beach cusps. This is consistent with a “morphological coupling” hypothesis that hydrodynamic-morphodynamic feedbacks between the swash and upper-beach cusps can form lower-beach cusps with a related wavelength as the tide falls. However, sometimes the high-tide waterline reaching the upper-beach cusps did not result in a unified beach state. This suggest that morphological coupling is often an important factor in controlling the development of new lower-beach cusps but cannot initiate cusp formation in hydrodynamic conditions outside those favorable for cusp activity.

29 Jul 2024

Rectifying and Stabilizing Planet SkySat Video Collects for Bathymetric Inversions from Space

Abstract: This Coastal and Hydraulics Engineering Technical Note (CHETN) presents the development of a workflow to process Planet SkySat videos collected from space at the US Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), Field Research Facility (FRF), in Duck, North Carolina, to derive wave kinematics and perform bathymetric inversions. The document summarizes the nine 30–60 s* satellite video collections, demonstrates the accuracy of an automated rectification and stabilization workflow, and applies a new short-dwell version of a common inversion algorithm (cBathy) to demonstrate the utility of short-dwell videos from space providing an initial out-of-the-box assessment of errors for one of the collections, and recommends future avenues of research for improving bathymetric predictions.

16 Jul 2024

Evaluation of the Version 1 Advanced Tactical Awareness Kit–Expeditionary Radar (ATAK-ER V1) for Accuracy and Reliability in Surf-Zone Characterization in a Range of Environmental Conditions

Abstract: This Coastal and Hydraulics Engineering Technical Note (CHETN) presents the evaluation of a rapidly deployable radar and associated software for characterizing surf-zone waves, currents, and bathymetries at the US Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), Field Research Facility (FRF), in Duck, North Carolina. This project was conducted at the request of the US Marine Corps (USMC) Warfighting Laboratory. The Version 1 Advanced Tactical Awareness Kit–Radar Expeditionary (ATAK-ER V1) system was deployed 15 times between July and August 2023 to observe a range of wave, water level, and wind conditions that could each affect radar processing. Products from the system were then compared to the FRF’s continuously operating in situ instruments and monthly bathymetric surveys to quantify the accuracy and reliability of the output. A number of issues with the unit are identified, including potential error sources contributing to inaccuracies, but the black-box nature of the commercial off-the-shelf (COTS) unit prevents a confident understanding of why wave heights are underpredicted (by 65% on average), why bathymetries consistently have root-mean-square errors (RMSE) over 1 m with progressively greater errors with distance offshore, or why some collections are unable to generate all of the advertised products. This Version 1 COTS unit is not recommended for operational use at this time.

11 Jul 2024

Sharing Ships’ Weather Data via AIS: Concept and Results from Multiyear Observations

Abstract: The purpose of this Coastal and Hydraulics Engineering technical note (CHETN) is to discuss the concept, demonstrations, and the initial results of multiyear proof-of-concept testing of the capability to share weather data from ships via the Automatic Identification System (AIS). Technical foundations of this process were described by Tetreault and Johnson (2020) with partial results described in Johnston et al. 2021. The updated results in this CHETN include evaluation of the efficacy of the various application-specific message (ASM) formats use to communicate the weather observations and data reception results for selected vessels that have been participating in the proof-of-concept field deployment since 2019 or later.

11 Jul 2024

Mississippi River AdH Model Modification and Evaluation, Thebes, Illinois, to Birds Point, Missouri, Reach

Abstract: A calibrated hydrodynamic and sediment transport model of the Upper Mississippi River, from Thebes, Illinois, to Birds Point, Missouri, was created to investigate hydraulics and sediment transport in the river channel and across the Dogtooth Island Peninsula (DIP) as the result of the Len Small levee breach. A hydrodynamic model was developed for the reach and calibrated to stage and breach outflow discharge data for the floods of 2011, 2015–2016, and 2017. The hydrodynamic model was used to investigate breach outflow discharges and shear stress distribution over the DIP. Soil and geologic maps were investigated to determine soil parameters and the long-term stability of soil formations on the DIP. The Upper Mississippi River sediment transport model was built upon the hydrodynamic model and soil mapping efforts. The sediment transport model was calibrated to the 2015 and 2017 flood events. Calibration data were limited to changes in elevation, which were then areally averaged, computed from comprehensive channel surveys and lidar data for the DIP. This model provides a solid foundation for comparing alternative measures to minimize further erosion of the DIP and for analyzing the risk of a channel cutoff occurring.

25 Jun 2024

US Army Corps of Engineers (USACE) Wave Information Study: 2021 Annual Update

Purpose: This Coastal and Hydraulics Engineering Technical Note (CHETN) describes the 2021 Wave Information Study (WIS) annual update. Within this CHETN, we summarize the WIS input data, explain the model technologies, detail the quality control / quality assurance (QA/QC), and provide statistical evaluation of the 2021 WIS estimates as compared to in situ buoys and remotely sensed satellite altimeter data.

25 Jun 2024

The Effect of Increasing the Antenna Height on Radio Signal Reception at Tom Bevill Lock and Dam: LOMA-AIS Data Case Study

Abstract: This Coastal and Hydraulics Engineering Technical Note (CHETN) presents the effects on the reception of radio signals due to increasing the antenna height at Tom Bevill Lock and Dam (L&D) in Pickensville, Alabama. The signals are received Automatic Identification System (AIS) broadcasts from commercial vessels operating along the Tennessee-Tombigbee Waterway. These AIS broadcasts are received by the Lock Operations Management Application (LOMA) radio equipment at Tom Bevill L&D.

21 Jun 2024

Observations of Beach Change and Runup, and the Performance of Empirical Runup Parameterizations during Large Storm Events

Abstract: Timeseries observations of beach elevation change and wave runup from a tower-mounted stationary lidar assess the skill of 2% runup exceedance (𝑅2%) estimates during four storm events at Duck, NC. The runup parameterization requires the foreshore beach slope, which generally unknown during high energy events. Pre-storm estimates are often used as a proxy. 𝑅2% hindcasts use the observed time-varying beach slope and a static pre-storm beach profile, yielding an 𝑅2% skill of 0.57. The skill drops to −1.0 using seasonal mean beach slopes and reduces after the peak of two storms with the appearance of beach cusps in the swash zone morphology. One storm’s runup is underpredicted by up to 1.0 m at high tides following the storm peak when cusps are present Additional pre- and post-storm mobile lidar surveys for one storm confirm ubiquitous small-scale beach cusps along 8 km of the local shoreline. The results suggest skillful runup estimates are often attainable given the availability of beach information before a storm. The parameterization errors increase when beach cusps develop, highlighting the need to extend standard one-dimensional runup parameterizations to account for two-dimensional effects.

14 Jun 2024

Application of Coastal Resilience Metrics at Panama City Beach, Florida

Abstract: This study, for the first time, combines the Coastal Engineering Resilience Index (CERI) and Buffer Width (BW) metrics to better understand the historic, current, and future resilience of the coastal system at Panama City Beach, Florida. After the construction of the US Army Corps of Engineers Coastal Storm Risk Management (CSRM) project at Panama City Beach, the CERI resilience metric has increased up to 21.3%, while negative storm impacts in the same have been less than 8%. The frequency of nourishment efforts moving forward is justified by a 24.3% increase in the BW metric when comparing cases that are nourished frequently with cases that are not nourished frequently. Moreover, there is a 129.2% increase in the BW metric when comparing the frequently nourished cases with the cases that are nourished only on an emergency basis. While the CERI and BW metrics have both been considered previously, their combined application provides an understanding of a broader temporal view of how storm events, CSRM projects, and nourishments have played a part in the resilience of the system at Panama City Beach over the last two decades and how they may play a role in the next half century.