14 Feb 2024

Hydraulic Sorting of Dredged Sediment in a Pipeline: An Evaluation of the Sediment Distribution Pipe

Abstract: The US Army Corps of Engineers (USACE) recently established a goal to beneficially use 70% of material dredged from the nation’s navigable waterways by the year 2030. Most of the sediments dredged by the USACE are heterogeneous mixtures of mud and sand, which can limit beneficial use of dredged material (BUDM) applications. Innovative technologies that can sort material during the dredging process are needed to help increase BUDM practices. This investigation sought to evaluate the ability of a sediment distribution pipe (SDP) to sort particles during transport in a pipeline. Field demonstrations were conducted during dredged material placements at Sturgeon Island, New Jersey. Velocity within the pipeline was found to be inadequate for efficient hydraulic sorting of fines (<75 μm) and produced inconclusive results. Small scale laboratory SDP experiments found that effluent from the SDP holes had an altered sediment texture compared to the initial slurry and that hydraulic sorting was occurring within the pipeline. However, outflow from the SDP holes was inconsistent, and typically >90% of the sediment mass was discharged out the end of the pipeline. Sorting efficiency of the SDP could not be accurately assessed in the current experimental configuration.

22 Jan 2024

Amphibious Uncrewed Ground Vehicle for Coastal Surfzone Survey

Abstract: The capability of a commercial off-the-shelf amphibious bottom crawling robot is explored for surveying seamless topography and bathymetry across the beachface, surfzone, and very nearshore. A real-time-kinematic (RTK) antenna on a mast was added to the robotic platform, a Bayonet-350 (previously the C2i SeaOx). Data collected from the robot were compared with those collected by the Coastal Research Amphibious Buggy (CRAB) and the Lighter Amphibious Resupply Cargo (LARC), unique amphibious vessels capable of collecting seamless topography and bathymetry in use for decades at the US Army Engineer Research and Development Center’s Field Research Facility (FRF). Data were compared on five different days in a range of wave conditions (Hs < 1 m in 8-m depth) resulting in a root-mean square difference of 8.7 cm and bias of 2 cm for 24 different cross-shore profile comparisons. Additionally, a repeatability test was performed to assess measurement uncertainty. The repeatability test indicated a total vertical uncertainty (TVU) of 5.8 cm, with the highest spatial error at the shoreline.

11 Jan 2024

An Examination of Multihazard Marine Transportation System (MTS) Response and Recovery Operations during the 2020 Hurricane Season

Abstract: The Committee on the Marine Transportation System (CMTS), Resilience Integrated Action Team (RIAT), was established in 2014 to foster the coordination and coproduction of knowledge that incorporates the concepts of resilience into the marine transportation system (MTS). The RIAT defines resilience as a four-phase cycle that incorporates preparation, response, recovery, and adaptation activities to minimize disruption to the MTS. The RIAT utilizes this definition of resilience to convene first-responder CMTS agencies to examine challenges and successes and make recommendations about past hurricane seasons. The 2020 hurricane season saw a record-breaking number of storms form in the Atlantic basin during a global pandemic. As a result, federal agencies were challenged to operate in a multihazard posture, and many former lessons learned needed to be adjusted to this unprecedented situation.

9 Jan 2024

Preliminary Permafrost Predictions within the Chena River Watershed, Alaska, Using Landscape Characteristics

Purpose: This Technical Note presents a method to create permafrost predictions in the Chena River watershed near Fairbanks, Alaska, using landscape characteristics. We produced probabilities for near-surface permafrost in the Chena River watershed using a published algorithm applied in a nearby region. The methodology presented serves as a proof of concept for developing permafrost maps using similar data in other cold regions.

8 Jan 2024

Review of Regressive Channel Erosion and Grade Control Options on the Rio Coca, Ecuador

Purpose: The US Army Corps of Engineers (USACE) is assisting the Ecuadorian state-run Corporación Eléctrica del Ecuador (CELEC) in addressing a water resource issue involving regressive channel erosion on the Rio Coca. Reconnaissance of the site was completed the week of 21 February 2022; parts of the river system were viewed to determine if improvements could be made to the current grade control structure (GCS) mitigation plan for reducing channel erosion and stabilizing the river system downstream of the Coca Coda Sinclair (CCS) Dam. The Rio Coca is a tributary to the Amazon River system in South America. It originates on the east side of the Andes Mountains and generally flows from southwest to northeast through the project area and then turns and flows east into the Amazon basin (Figure 1).* The Rio Coca valley is a current example of how damaging regressive erosion can be to a fluvial system (Figure 2).

15 Dec 2023

Ranking Ports by Vessel Demand for Depth

Abstract: The US Army Corps of Engineers (USACE) traditionally uses two metrics to evaluate the maintenance of coastal navigation projects: tonnage at the associated port (representing relative importance) and the controlling depth in the channel (representing operating condition). These are incorporated into a risk-based decision framework directing funds where channel conditions have deteriorated and the disrupted tonnage potential is the highest. However, these metrics fail to capture shipper demand for the maintained depth service provided by the USACE through dredging. Using automatic identification system (AIS) data, the USACE is pioneering new metrics describing vessel demand for the channel depth, represented by vessel encroachment volume (VEV). VEV describes the volume of the hull intruding into a specified clearance margin above the bed and captures how much vessels use the deepest portions of USACE-dredged channels. This study compares the VEV among 13 ports over 4 years by combining AIS, tidal elevations, channel surveys, and sailing draft. The ports are ranked based on the services demanded by their user base to inform the decision framework driving dredge funding allocations. Integrating demand for-depth metrics into the Harbor Maintenance Fee assessment and/or Trust Fund disbursements could alleviate the constitutionality concerns and several criticisms levied against Harbor Maintenance funding.

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.