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.

7 Aug 2024

A Broadscale Assessment of Sentinel-2 Imagery and the Google Earth Engine for the Nationwide Mapping of Chlorophyll a

Abstract: Harmful algal blooms degrade water quality and can adversely impact human and wildlife health. Monitoring these at scale is difficult due to the lack of coincident data. Additionally, traditional field collection methods are labor- and cost-prohibitive, resulting in disparate data collection in capable of capturing the physical and biological variations within waterbodies or regions. This research attempts to alleviate this by leveraging large, public, water quality databases and open-access Google Earth Engine-derived Sentinel-2 imagery to evaluate the practical usability of four common chlorophyll a algorithms as a proxy for detecting and mapping algal blooms nationwide. Chlorophyll a data were aggregated from spatially diverse sites across the continental US between 2019 and 2022. The 2BDA and the NDCI algorithms were the most viable for broadscale mapping of chlorophyll a, which performed moderately well, encompassing highly diverse spatial, temporal, and physical conditions. The most compatible field data acquisition method was the chlorophyll a, water, trichromatic method, uncorrected. Resulting data indicate the feasibility of utilizing band ratio algorithms for broadscale detection and mapping of chlorophyll a as a proxy for HABs, which is valuable when coincident data are unavailable or limited.

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.

1 Aug 2024

Detection and Decay of Different Classes of Environmental RNA (eRNA) from Zebrafish (Danio rerio)

Purpose: This technical note contributes to the growing body of knowledge about macroscopic eukaryotic environmental RNA (eRNA) by exploring detection and decay for several different zebrafish (Danio rerio) eRNAs in a mesocosm setting. The study addressed four basic hypotheses: (1) D. rerio would deposit detectable levels of eRNA into water, (2) different classes of eRNA would be detected, (3) different eRNA sequences (for example, loci) would degrade at different rates, and (4) abiotic and biotic factors would influence rates of degradation. For the last hypothesis, we tracked eRNA concentration decay under treatments with different water temperatures and levels of microbiological activity, two factors known to significantly influence environmental DNA (eDNA) decay (Barnes et al. 2014; Lance et al. 2017; Nielsen et al. 2007; Strickler et al. 2015).

31 Jul 2024

Reservoir Sediment Deltas of the Southwestern United States: Challenges and Opportunities for Riparian Vegetation Management

Purpose: This technical note summarizes methods used to identify 58 reservoir sediment deltas in the Southwestern United States and California, behind 47 different dams, with potential regional importance as breeding or migratory stopover habitat for three species of riparian vegetation–dependent birds listed under the Endangered Species Act[1]: least Bell’s vireo (LBVI) (Vireo bellii pusillus), southwest willow flycatcher (SWFL) (Empidonax traillii extimus), and yellow-billed cuckoo (YBCU) (Coccyzus americanus). Information on inflow streams, drainage area, and management authority are provided for each delta. This technical note recommends follow-up research on the temporal dynamics of vegetation colonization, growth, and mortality on these deltas to explore the potential value of these geographically widespread hydrogeomorphic features on arid-land rivers for the conservation of riparian vegetation–dependent birds.

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.

25 Jul 2024

Regeneration Dynamics of Bottomland Hardwood Sites Following Prolonged Growing-Season Inundation

Abstract: The spring flood of the Mississippi River and backwater areas in 2019 resulted in large-scale flooding and was the longest-lasting flood event since the Great Flood of 1927. This flood event provided a rare opportunity to establish permanent plots in batture and backwater habitats to evaluate forest-stand dynamics following prolonged flooding. In this study, we evaluated postflooding conditions of forest overstory, midstory, and regeneration by establishing permanent plots at four locations subjected to varying amounts of flooding within the Mississippi River batture and the Yazoo–Mississippi Delta backwater region. Our results highlight oak regeneration success following the 2019 flood event as well as the utility and need to establish and monitor permanent plots to increase our understanding of floodplain forest dynamics in regions experiencing prolonged riverine flooding during the growing season.

23 Jul 2024

A/E/C Computer-Aided Design (CAD) Standard: Release 6.2

Abstract: The A/E/C Computer-Aided Design (CAD) Standard has been developed by the CAD/Building Information Modeling (BIM) Technology Center for Facilities, Infrastructure, and Environment to eliminate redundant CAD standardization efforts within DoD and the Federal Government. This manual is part of an initiative to develop a nonproprietary CAD standard that incorporates existing industry, national, and international standards and to develop data standards that address the entire life cycle of facilities within DoD. The material addressed in the A/E/C CAD Standard includes level/layer assignments, digital file naming, and standard symbology. The CAD/BIM Center’s primary goal is to develop a CAD standard that is generic enough to operate under various CAD software packages (such as Bentley’s MicroStation and Autodesk’s AutoCAD) while incorporating existing industry standards when possible. While this Standard encompasses many CAD concepts and practices, it is not intended to limit the capabilities of other advanced modeling software. Ultimately, a BIM / Civil Information Modeling standard will be developed to standardize the additional capabilities of other software.

23 Jul 2024

Signal Power Distributions for Simulated Outdoor Sound Propagation in Varying Refractive Conditions

Abstract: Probability distributions of acoustic signals propagating through the near-ground atmosphere are simulated by the parabolic equation method. The simulations involve propagation at four angles relative to the mean wind, with frequencies of 100, 200, 400, and 800 Hz. The environmental representation includes realistic atmospheric refractive profiles, turbulence, and ground interactions; cases are considered with and without parametric uncertainties in the wind velocity and surface heat flux. The simulated signals are found to span a broad range of scintillation indices, from near zero to exceeding ten. In the absence of uncertainties, the signal power (or intensity) is fit well by a two-parameter gamma distribution, regardless of the frequency and refractive conditions. When the uncertainties are included, three-parameter distributions, namely, the compound gamma or generalized gamma, are needed for a good fit to the simulation data. The compound gamma distribution appears preferable because its parameters have a straight forward interpretation related to the saturation and modulation of the signal by uncertainties.