11 Sep 2024

Bathymetric Inversion from Unmanned Aircraft System (UAS) Video on Inland Waters, Port Huron, Michigan

Abstract: This Coastal and Hydraulics Engineering Technical Note (CHETN) presents a proof of concept for the use of the cBathy algorithm to estimate bathymetry in an inland water environment. The document summarizes the methods used in collecting and analyzing stationary UAS (unmanned aircraft system) video taken at the Fort Gratiot Lighthouse Park in Port Huron, Michigan, a shoreline overseen by the US Army Corps of Engineers (USACE), Detroit District (LRE). The results presented in this report show that the cBathy algorithm has the potential to measure bathymetry in areas of inland water with sufficient fetch to generate wind swell, similar to how cBathy has been used in open-coast nearshore environments.

11 Sep 2024

Evaluating Topographic Reconstruction Accuracy of Planet Lab’s Stereo Satellite Imagery

Abstract: The goal of this Coastal and Hydraulics Engineering Technical Note (CHETN) is to document initial results to derive topography on the beachface in the northern Outer Banks, North Carolina, utilizing Planet Labs’ SkySat stereo panchromatic imagery processed in Agisoft Metashape. This technical note will provide an initial evaluation into whether Planet Lab’s SkySat imagery is a suitable image source for satellite Structure from Motion (SfM) algorithms as well as whether these data should be explored as a federal beach project monitoring tool. Depending on required accuracy, these data have the potential to aid coastal scientists, managers, and US Army Corps of Engineers (USACE) engineers in understanding the now-state of their coastlines and employ cost-effective adaptive management techniques.

11 Sep 2024

Coastal Hazards System–South Atlantic (CHS-SA)

Abstract: The US Army Corps of Engineers completed the South Atlantic Coastal Study (SACS) 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 CHS-SACS was to quantify storm hazards for present conditions and future sea level rise scenarios to reduce flooding risk and increase resiliency in coastal environments. CHS-SACS was completed for three regions within the SAD domain, and this report focuses on the South Atlantic (CHS-SA). This study applied the CHS’ Probabilistic Framework with Joint Probability Method Augmented by Metamodeling Prediction (JPM-AMP) to perform a probabilistic coastal hazard analysis (PCHA) of tropical cyclone (TC) and extratropical cyclone (XC) responses, leveraging new atmospheric and hydrodynamic numerical model simulations of synthetic TCs and historical XCs. This report documents the CHS probabilistic framework to perform the PCHA for CHS-SA by executing the JPM-AMP, including storm climate characterization, storm sampling, storm recurrence rate estimation, marginal distributions, correlation and dependence structures of TC atmospheric-forcing parameters, development of augmented storm suites, and assignment of discrete storm weights to the synthetic TCs. Coastal hazards were estimated for annual exceedance frequencies over the range of 10 yr−1 to 10−4 yr−1.

11 Sep 2024

New Metrics for Managing Waterways: Vessel Encroachment Volume for Selected South Atlantic Division Ports

Abstract: The US Army Corps of Engineers (USACE) uses two metrics to evaluate maintenance for coastal navigation projects: cargo tonnage at the associated port and the controlling depth in the channel relative to the authorized channel depth. These are calculated through normal business practices and describe the relative importance (tonnage) of the port and the operating condition (controlling depth) of the channel. They are incorporated into a risk-based decision framework that directs funds to locations where channel conditions have deteriorated. Using Automatic Identification System (AIS) vessel-position data, USACE is pioneering the computation of metrics related to the space between the hull of transiting vessels and the waterway bed for channels, the underkeel clearance. This and related metrics describe how waterway users take advantage of the service provided directly by USACE (maintained channel depth). This study compares the underkeel clearance metrics among 13 ports in the South Atlantic Division over a span of 3 years by combining marine vessel AIS data, tidal predictions, channel bathymetric surveys, and vessel sailing draft. Comparing these values across ports allows these metrics to be integrated into the decision framework that drives dredge funding allocations.v

6 Sep 2024

Use of Chirp Sub-Bottom Acoustics to Assess Integrity of Water-Control Structures: Inner Harbor Navigation Canal Lock, New Orleans

Abstract: The US Army Corps of Engineers (USACE)-maintained lock on the Inner Harbor Navigation Canal serves as a critical navigation link between Lake Pontchartrain to the north and the Mississippi River to the south. Extensive slumping has been observed on the earthen embankment on each side of the lock, suggesting that internal pathways for water to escape through the lock’s concrete walls or joints are present. Unfortunately, traditional methods often used to identify cracks in the concrete (e.g., sidescan sonar) or water-filled voids under or behind the structure (e.g., ground-penetrating radar) did not identify any structural issues at this site. Prior to dewatering and repair, the USACE New Orleans District requested that the US Army Engineer Research and Development Center conduct a sub-bottom survey at the lock in order to identify water-filled voids and better prepare for potential repairs during dewatering. A unique sled was constructed that allowed a small vessel to tow the sub-bottom profiler at an angle to direct more acoustic energy into the structure. Low frequency, chirp acoustic energy successfully penetrated the concrete walls and identified several water-filled voids on both sides of the lock. A later post-dewatering walk-through indicated that the chirp imaged voids spatially adjacent to cracks, and cracks were not found in any other locations. Additional work is needed to further develop this methodology in other USACE structures.

28 Aug 2024

Integrating NOAA’s National Water Model (NWM) into the Antecedent Precipitation Tool (APT) to Support Clean Water Act Decision-Making

Abstract: This study examines the effectiveness of the National Water Model (NWM) in assessing streamflow normalcy under the Clean Water Act, compared to the commonly used Antecedent Precipitation Tool (APT). The APT, used by the Environmental Protection Agency, US Army Corps of Engineers, and environmental consultants, evaluates waterbody conditions based on precipitation data. However, it was found to be less accurate in predicting streamflow normalcy compared to USGS gage data. The NWM, on the other hand, showed promising results in preliminary analyses, outperforming the APT when compared to USGS gage records. This research expands on these initial findings, evaluating the NWM’s performance across the contiguous United States (CONUS) at gage locations indexed to the NHDPlus Version 2.1 stream network. The results suggest that the NWM provides adequate performance for assessing streamflow normalcy where USGS gages are not present, with accuracy ranging from 40% to 60% in the western half of CONUS and 60% to 80% in the eastern half.

26 Aug 2024

FUNWAVE-TVD Testbed: Analytical, Laboratory, and Field Cases for Validation and Verification of the Phase-Resolving Nearshore Boussinesq-Type Numerical Wave Model

Abstract: Over the last couple of decades, advancements in high-performance computing have allowed phase-resolving, Boussinesq-type numerical wave models to be more practical in addressing nearshore coastal wave processes. As such, the open-source FUNWAVE-TVD numerical wave model has become more ubiquitous across all scientific and engineering-focused R&D organizations, including academic, government, and industry partners. In collaboration with the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory; the University of Delaware; and HR Wallingford, a robust testbed has been developed to allow users to benchmark their applications against new releases of the model. The testbed presented here includes analytical, laboratory, and field cases, to provide guidance on the operational utility of FUNWAVE-TVD and examines numerical convergence, accuracy, and performance in modeling wave generation, propagation, wave breaking, and moving shorelines in nearshore wind-wave applications. A brief discussion on the efficiency of the model across parallel computing platforms is also provided.

22 Aug 2024

Application of Existing Tools to Systematically Identify Nearshore Placement Sites for Beneficial Use of Navigation Sediments in Lake Michigan

Purpose: The Great Lakes includes 140 federally maintained harbors with an annual dredging program of 2–4 million cubic meters (3–5 million cubic yards)[1] of sediment. Many small harbors are not dredged regularly, and there is an undredged backlog of over 9 million cubic meters (12 million cubic yards) of sediment (USACE-LRD 2021). Current policy (Spellmon 2023) is to maximize the beneficial use (BU) of sediment, with a goal of beneficially reusing 70% of the federal navigation dredging volume by 2030 (that is, the 70/30 goal). In the Great Lakes, clean sands have often been placed on beaches or in the nearshore littoral zone to beneficially nourish the shoreline, but since many harbors are not dredged regularly, no plans exist to beneficially reuse dredged sediments. This lack of existing BU plans is particularly true for harbors with finer grained or mixed sediment. To achieve the 70/30 BU goal and support navigation maintenance and coastal management requires a strategic and systematic approach to identifying BU sites. The purpose of the technical note is to (1) provide an approach to identify potential nearshore placement sites using existing information and models; (2) describe available tools for placement site identification, coastal condition information, and the long-term fate of the sediment; and (3) provide a pertinent case study to describe this approach in practice.

7 Aug 2024

Traveling Kevel Load Analysis for Inland Locks, Phase I: Previous Failures

Abstract: The US Army Engineer Research and Development Center (ERDC) has begun an investigation of the load conditions experienced by a traveling kevel when moored to a moving barge train. These traveling kevel systems are essential for the safe and efficient use of the US Army Corps of Engineers (USACE) navigation lock inventory. This work is being conducted as part of the Navigation Systems Research Program of the Coastal and Hydraulics Laboratory (CHL). Recent failures of traveling kevels suggest that the existing design guidance for design loads for traveling kevels may need updating. This Coastal and Hydraulics Engineering Technical Note (CHETN) describes the pertinent background information and the current issues related to previous traveling kevel failures.

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.