4 Apr 2024

Use of Sediment Tracers to Evaluate Sediment Plume at Beaufort Inlet and Adjacent Beaches, North Carolina

Abstract: This report documents a numerical modeling investigation on the transport of sediment material placed on designated disposal sites adjacent to Beaufort Inlet, North Carolina. Historical and newly collected wave and hydrodynamic data around the inlet are assembled and analyzed. The data sets are used to calibrate and validate a coastal wave, hydrodynamic and sediment transport model, the Coastal Modeling System. Model alternatives are developed corresponding to different material placement sites. Sediment transport and sediment plume distribution are evaluated within and around the immediate vicinity of the Beaufort Inlet estuarine system for a representative summer and winter month. Results of model simulations show that high flows occur along navigation channels and low flows occur outside the inlet in open ocean area. Sand materials placed in nearshore sites tend to be trapped in and move along navigation channels entering the inlet. In offshore placement sites the sediment plume shows slow spreading and no significant sand migration from its release locations. Simulations for the summer and winter month present similar distribution patterns of sediments originating from placement sites.

26 Mar 2024

Risk-Based Prioritization of Operational Condition Assessments: Trinity River and Willamette River Case Studies

Abstract: The US Army Corps of Engineers (USACE) operates, maintains, and man-ages over 700 dams and 4,000 miles of levees, providing approximately $257 billion worth of economic benefit to the Nation. USACE employs the Operational Condition Assessment (OCA) process to understand the condition of those assets and allocate resources to minimize risk associated with performance degradation. Understanding risk in flood risk management (FRM) assets requires an understanding of consequence of asset failure from a systemwide FRM watershed perspective and an understanding of likelihood of degradation based on the condition of the low-level components derived from OCA ratings. This research demonstrates a case-study application of a scalable methodology to model the likelihood of a dam performing as expected given the state of its gates and their components. The research team combines this likelihood of degradation with consequences generated by the application of designed simulation experiments with hydrological models to develop risk measures. These risk measures can be developed for all FRM gate assets in order to enable traceable, consistent resource allocation decisions. Two case study applications are provided.

21 Mar 2024

Pilot Project Using Tickler Chains in Lieu of Deflectors at Fire Island Inlet to Moriches Inlet, New York, Borrow Sites

Abstract: Risk for incidental take of sea turtles and sturgeon exists during hopper dredging operations throughout turtle and sturgeon habitats. Since 1992, draghead deflectors have been the main engineering tool used to minimize incidental hopper dredging takes of sea turtles and are also thought to reduce the chance of sturgeon impingement entrainment. Although reduced, turtle takes still happen annually, and the draghead deflectors reduce dredging productivity, increase fuel usage, and increase costs of operations. As such, there remains a need to research alternative turtle avoidance measures. The non-US dredging industry has used various versions of an engineering control called tickler chains (TC) in lieu of deflectors. If effective, TC could lower dredging costs and increase production in comparison to deflectors. This technical report describes a pilot study where TC were used in lieu of deflectors at Fire Island Inlet, New Y0rk. To the authors’ knowledge, this is the first time since the early 1990s that hopper-dredging has occurred without draghead deflectors along the east coast. No takes were recorded during the pilot study; however, no research was done to determine if sea turtles or sturgeon interacted with the TC. Recommendations for future TC research is provided in this technical report.

21 Mar 2024

A Beneficial Placement Decision Support Framework for Wetlands: Case Study for Mobile Harbor, USA

Abstract: The US Army Corps of Engineers, in the responsibility of maintaining navigational infrastructure, has a unique opportunity to improve coastal wetland resiliency and conserve coastal natural infrastructure through the beneficial use of dredged material for wetland restoration. Opportunities are widespread, and tools such as biophysical models can aid coastal managers in assessing habitat vulnerability and planning restoration. In this study, the Marsh Equilibrium Model was utilized in concert with observed data to predict future conditions and evaluate potential effects of beneficial use of dredged material to restore marshes in Mobile Harbor, Alabama. A range of site conditions and two restoration strategies were considered, and the subsequent impact to dredged material management area volumes evaluated. Results showed that wetland restoration via the thin-layer placement of dredged material can restore marsh elevation to combat sea level rise and conserve fill capacity at dredged material management areas. This approach is demonstrated for adoption nationwide by coastal managers.

18 Mar 2024

User Guidelines on Catchment Hydrological Modeling with Soil Thermal Dynamics in Gridded Surface Subsurface Hydrologic Analysis (GSSHA)

Abstract: Climate warming is expected to degrade permafrost in many regions of the world. Degradation of permafrost has the potential to affect soil thermal, hydrological, and vegetation regimes. Projections of long-term effects of climate warming on high latitude ecosystems require a coupled representation of soil thermal state and hydrological dynamics. Such a coupled framework was developed to explicitly simulate the soil moisture effects of soil thermal conductivity and heat capacity and its effects on hydrological response. In the coupled framework, the Geophysical Institute Permafrost Laboratory (GIPL) model is coupled with the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model. The new permafrost heat transfer in GSSHA is computed with the GIPL scheme that simulates soil temperature dynamics and the depth of seasonal freezing and thawing by numerically solving a one-dimensional quasilinear heat equation with phase change. All the GIPL input and output parameters and the state variables are set up to be consistent with the GSSHA input-output format and grid distribution data input requirements. Test-case simulated results showed that freezing temperatures reduced soil storage capacity, thereby producing higher peak and lower base flow. The report details the functions and format of required input variables and cards, as a guideline, in GSSHA hydrothermal analysis of frozen soils in permafrost active areas.

18 Mar 2024

Building Elevation in Mangrove Communities: Use of Regional Sediment Management to Increase Coastal Wetland Resilience to Sea-Level Rise

Abstract: This Regional Sediment Management technical report outlines initial steps to implement a proof-of-concept physical model to develop demonstration scale evidence that supports managed wetland transgression through sediment augmentation via a thin-layer placement strategy. The proof-of-concept physical model will evaluate the ability of thin-layer placement to increase elevation and enhance recruitment within coastal scrub mangrove wetlands most vulnerable to sea-level rise. The investigation sought to identify feasible project locations, sediment sources that included beneficial use of dredged material opportunities, and environmentally acceptable construction techniques. Results of this initial step will be used to secure funding to permit, construct, implement, and monitor the proof-of-concept physical model. The results of this initiative will inform and direct management measure development for the ongoing Biscayne Bay Southeastern Everglades Restoration Project, the only coastal component of the Comprehensive Everglades Restoration Plan and the only component with an obligation to increase habitat resilience. Results are applicable to areas throughout the Gulf, Atlantic, and Pacific Coasts of the United States where direct preservation, enhancement, and restoration of mangrove and other coastal wetland communities will build coastal resiliency, reduce storm hazards damage, and create habitat for a variety of fish and wildlife species, particularly as sea levels rise.

29 Feb 2024

Waterway Engineering Applications of Automatic Identification System Data along the Mississippi River and at Lock Structures

Abstract: The USACE, St. Louis District, is responsible for maintaining navigation channels along with multiple lock and dam structures on the Mississippi River, a vital inland waterway that carries millions of tons of commodities every year. Understanding commercial vessel traffic patterns is fundamental to informing decisions about construction projects and to efforts to improve communication to mariners. Automatic Identification System (AIS) data provides time-stamped and geo-referenced vessel position reports for most commercial vessels operating in the District’s area of interest. This paper describes how AIS data has been successfully used by St. Louis District waterway managers to (1) prevent conflicts with the navigation industry by revealing active fleeting areas that were under consideration for the construction of river training structures; and (2) identify changes in vessel approaches to a lock structure under different river flow conditions, providing operational information that could be used in future navigation alerts to mariners. This paper concludes with a list of suggested best practices for waterways managers who want to start, or expand, their use of AIS data.

29 Feb 2024

Hurdles to Beneficial Use of Dredged Material: Root Cause Analysis

Purpose: This technical note (TN) summarizes high points of an internal review of US Army Corps of Engineers (USACE) dredging and dredged material management practices, specifically beneficial use of dredged material (BUDM), that USACE manages from various navigation channels and ports around the nation.

28 Feb 2024

Ecological Model to Evaluate Borrow Areas in the Lower Mississippi River

Abstract: An aquatic analysis of constructing borrow areas adjacent to the main line levees in the Lower Mississippi River was conducted as part of an Environmental Impact Statement for upgrading the levee system. A Habitat Suitability Index (HSI) regression model based on field collections was developed to predict fish species richness as a function of the morphometry and water quality of borrow areas. The HSI score was multiplied by acres of borrow areas created during construction to obtain habitat units (HUs) for each alternative indicating a substantial gain of fishery habitat in the floodplain. Environmental features identified by the model to increase fish species richness and overall habitat heterogeneity include the shape of the pit (e.g., bowl-shaped with deep water rather than long rectangular with shallower water), the availability of littoral areas for fish spawning and rearing, using best management practices such as tree screens and bank stabilization to lower turbidity, adding islands, and creating sinuous shorelines. The project results in an overall gain in aquatic habitat by creating permanent or semi-permanent water bodies on the floodplain that our research indicates may be occupied by at least 75 species of fish contributing to the overall biodiversity of the lower Mississippi River.

28 Feb 2024

Potential Lock Operations Management Application (LOMA) Hardware Installation Sites along the Ohio River to Improve Automatic Identification System (AIS) Reception and Transmit Range

Abstract: The purpose of this Coastal and Hydraulics Engineering technical note (CHETN) is to propose a list of candidate sites along the Ohio River for the installation of Automatic Identification System (AIS) shoreside towers within the US Army Corps of Engineers (USACE) Lock Operations Management Application (LOMA) program. The LOMA program manages a network of terrestrial (shoreside) AIS sites (Figure 1) and vessel-mounted AIS sites with receive and transmit capability. However, there are known limits to the reception and transmission areas served by existing shoreside towers (referred to as “coverage gaps”) along the Ohio River (DiJoseph et al. 2021). Parties interested in improving AIS coverage to enhance maritime domain awareness and navigational safety along the Ohio River may wish to pursue the installation of LOMA program hardware for this purpose.