2 May 2024

Data-Driven Modeling of Groundwater Level Using Machine Learning

Purpose: This US Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory engineering technical note (CHETN) documents a preliminary study on the use of specialized machine learning (ML) methods to model the variations in groundwater level (GWL) with time. This approach uses historical groundwater observation data at seven gage locations in Wyoming, USA, available from the USGS database and historical data on several relevant meteorological variables obtained from the ERA5 reanalysis dataset produced by the Copernicus Climate Change Service (usually referred to as C3S) at the European Center for Medium-Range Weather Forecasts to predict future GWL values for a desired period of time. The results presented in this report indicate that the ML method has the potential to predict both short-term (4-hourly) as well as daily variations in GWL several days into the future for the chosen study region, thus alleviating the need for employing sophisticated process-based numerical models with complicated model structure configurations.

15 Apr 2024

Development and Testing of the Sediment Distribution Pipe (SDP): A Pragmatic Tool for Wetland Nourishment

Abstract: Standard dredging operations during thin layer placement (TLP) projects are labor intensive as crews are necessary to periodically move the outfall location, which can have lasting adverse effects on the marsh surface. In an effort to increase efficiency during TLP, a novel Sediment Distribution Pipe (SDP) system was investigated. This system offers multiple discharge points along the pipeline to increase the sediment distribution while reducing pipeline movements. An SDP Modeling Application (SDPMA) was developed to assist in the design of SDP field applications by quickly assessing the pressure and velocity inside the discharge pipe and approximating the slurry throw distances. An SDP field proof of concept was performed during a two-phase TLP on Sturgeon Island, New Jersey, in 2020. The SDPMA was shown to be an accurate method of predicting performance of the SDP. The SDP was successful at distributing dredge material across the placement site; however, further research is warranted to better quantify performance metrics.

15 Apr 2024

Uncrewed Survey-Vessel Conversion

Purpose: The purpose of this study was to investigate the uses of an uncrewed survey vessel to maintain mission readiness of all federal navigation channels and ports. Developing an uncrewed survey vessel capable of collecting data in a riverine environment may increase the efficiency and resiliency of the US Army Corps of Engineers (USACE) missions and USACE districts to conduct surveys during post natural disasters and pandemics. This document describes the installation, enhancement, and modification of the commercial-off-the-shelf (COTS) system, the Sea Machines SM300, on a US Army Engineer Research and Development Center (ERDC) survey vessel to create a semiautonomous survey capability.

9 Apr 2024

Embracing Biodiversity on Engineered Coastal Infrastructure through Structured Decision-Making and Engineering With Nature

Abstract: Extreme weather variation, natural disasters, and anthropogenic actions negatively impact coastal communities through flooding and erosion. To safeguard coastal settlements, shorelines are frequently reinforced with seawalls and bulkheads. Hardened shorelines, however, result in biodiversity loss and environmental deterioration. The creation of sustainable solutions that engineer with nature is required to lessen natural and anthropogenic pressures. Nature-based solutions (NbS) are a means to enhance biodiversity and improve the environment while meeting engineering goals. To address this urgent need, the US Army Corps of Engineers (USACE) Engineering With Nature® (EWN) program balances economic, environmental, and social benefits through collaboration. This report presents how design and engineering practice can be enhanced through organized decision-making and landscape architectural renderings that integrate engineering, science, and NbS to increase biodiversity in coastal marine habitats. When developing new infrastructure or updating or repairing existing infrastructure, such integration can be greatly beneficial. Further, drawings and renderings exhibiting EWN concepts can assist in decision-making by aiding in the communication of NbS designs. Our practical experiences with the application of EWN have shown that involving landscape architects can play a critical role in effective collaboration and result in solutions that safeguard coastal communities while maintaining or enhancing biodiversity.

8 Apr 2024

Coastal Modeling System User’s Manual

Abstract: The Coastal Modeling System (CMS) is a suite of coupled 2D numerical models for simulating nearshore waves, currents, water levels, sediment transport, morphology change, and salinity and temperature. Developed by the Coastal Inlets Research Program of the US Army Corps of Engineers, the CMS provides coastal engineers and scientists a PC-based, easy-to-use, accurate, and efficient tool for understanding of coastal processes and for designing and managing of coastal inlets research, navigation projects, and sediment exchange between inlets and adjacent beaches. The present technical report acts as a user guide for the CMS, which contains comprehensive information on model theory, model setup, and model features. The detailed descriptions include creation of a new project, configuration of model grid, various types of boundary conditions, representation of coastal structures, numerical methods, and coupled simulations of waves, hydrodynamics, and sediment transport. Pre- and postmodel data processing and CMS modeling procedures are also described through operation within a graphic user interface—the Surface Water Modeling System.

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.