11 Sep 2024

Terrestrial Vision-Based Localization Using Synthetic Horizons

Abstract: Vision-based localization could improve navigation and routing solutions in GPS-denied environments. In this study, data from a Carnegie Robotics MultiSense S7 stereo camera were matched to a synthetic horizon derived from foundation sources using novel two-dimensional correlation techniques. Testing was conducted at multiple observation locations over known ground control points (GCPs) at the US Army Engineer Research and Development Center (ERDC), Geospatial Research Laboratory (GRL), Corbin Research Facility. Testing was conducted at several different observational azimuths for these locations to account for the many possible viewing angles in a scene. Multiple observational azimuths were also tested together to see how the amount of viewing angles affected results. These initial tests were conducted to help future efforts testing the S7 camera under more realistic conditions, in different environments, and while expanding the collection and processing methodologies to additional sensor systems.

11 Sep 2024

Modifications to an Amphibious Unoccupied Ground Vehicle (AUGV) for Survey Operations

Abstract: Developing unoccupied systems capable of collecting data in the very shallow water (<10 m) and surfzone (typically <3 m) is a challenging task for many reasons including waves, sediment, bubbles, and turbulent velocities. This document focuses on describing some of the additions, enhancements, and refinements to a commercial-off-the-shelf (COTS) system, the SeaOx, available from Bayonet Ocean Vehicles (previously C2i). In addition, practical experience in using this platform to collect data in the surfzone is documented.

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

11 Sep 2024

Helical Anchor Installation with the High Mobility Engineer Excavator: Proof-of-Concept Testing

Abstract: Proof-of-concept testing was conducted to determine the viability of helical anchor installation using the US Army’s High Mobility Engineer Excavator (HMEE). To facilitate the proof-of-concept test, a new hydraulic hose kit was designed that connects the Bridge Supplemental Set (BSS) drive motor to the HMEE’s auxiliary hydraulic system. Additionally, a steel mount was fabricated that provided means to attach the BSS drive motor to the boom of the HMEE. Testing indicated the HMEE can successfully install the BSS anchors with the required hardware, but the vehicle’s large footprint will likely increase the installation time compared to previous methods. Several improvements to the hydraulic hose kit design were identified through the experiment, and guidance was created to facilitate efficient HMEE usage in the future. Once a permanent solution is developed to mount the BSS drive motor to the HMEE, the capabilities of the BSS will be greatly expanded by allowing each Multi-Role Bridge Company to install anchors using multiple vehicle types.

11 Sep 2024

Evaluation of the Bridge Supplement Set overhead cable system with uneven bank heights

Abstract: A numerical model was developed to analyze the effects of environmental conditions and construction layout on the structural capacity of the modernized Bridge Supplemental Set (BSS). Environmental variables included even and uneven bank heights, soil strength, river width, and river flow rate conditions. Construction variables included tower placement, tower guy line orientation, and catenary length. Loading conditions, the drag force of the bridge due to river current, were conservatively applied with the assumption of uniform flow rate across the entire river width to account for the wide range of operating environments in which the BSS may potentially be used. Analysis of system performance informed several BSS construction optimizations to maximize system capabilities over the wide range of conditions considered. Catenary length was found to have the greatest influence on system performance, indicating that a small increase in catenary length would greatly reduce the loading on the critical components of the BSS, thus increasing the capacity and safety of the system. A stand-alone computer program was developed to quickly provide BSS construction guidance for a large variety of operating conditions, as the number of charts and figures required to account for most scenarios numbers in the thousands.

6 Sep 2024

Snow Surface Roughness across Spatio-Temporal Scales

Abstract: The snow surface is at the interface between the atmosphere and Earth. The surface of the snowpack changes due to its interaction with precipitation, wind, humidity, short- and long-wave radiation, underlying terrain characteristics, and land cover. These connections create a dynamic snow surface that impacts the energy and mass balance of the snowpack, blowing snow potential, and other snowpack processes. Despite this, the snow surface is generally considered a constant parameter in many Earth system models. Data from the National Aeronautics and Space Administration (NASA) Cold Land Processes Experiment (CLPX) collected in 2002 and 2003 across northern Colorado were used to investigate the spatial and temporal variability of snow surface roughness. The random roughness (RR) and fractal dimension (D) metrics used in this investigation are well correlated. However, roughness is not correlated across scales, computed here from snow roughness boards at a millimeter resolution and airborne lidar at a meter resolution. Process scale differences were found based on land cover at each of the two measurement scales, as appraised through measurements in the forest and alpine.

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.