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.

4 Jan 2024

ERDC-PT: A Multidimensional Particle Tracking Model

Abstract: This report describes the technical engine details of the particle- and species-tracking software ERDC-PT. The development of ERDC-PT leveraged a legacy ERDC tracking model, “PT123,” developed by a civil works basic research project titled “Efficient Resolution of Complex Transport Phenomena Using Eulerian-Lagrangian Techniques” and in part by the System-Wide Water Resources Program. Given hydrodynamic velocities, ERDC-PT can track thousands of massless particles on 2D and 3D unstructured or converted structured meshes through distributed processing. At the time of this report, ERDC-PT supports triangular elements in 2D and tetrahedral elements in 3D. First-, second-, and fourth-order Runge-Kutta time integration methods are included in ERDC-PT to solve the ordinary differential equations describing the motion of particles. An element-by-element tracking algorithm is used for efficient particle tracking over the mesh. ERDC-PT tracks particles along the closed and free surface boundaries by velocity projection and stops tracking when a particle encounters the open boundary. In addition to passive particles, ERDC-PT can transport behavioral species, such as oyster larvae. This report is the first report of the series describing the technical details of the tracking engine. It details the governing equation and numerical approaching associated with ERDC-PT Version 1.0 contents.

26 Sep 2023

Linking the SEDLZJ Portable Standalone Library to the CMS Coastal Hydrodynamic Model

PURPOSE: This document describes the repackaging and linkage of the Sandia National Laboratories Environmental Fluid Dynamics Sediment Processes Code (SNL-EFDC-SEDZLJ), (Thanh et al. 2008). It was originally incorporated within a modified version of the US Environmental Protection Agency’s (USEPA) EFDC public-domain surface-water flow, sediment transport, and water-quality model developed by John Hamrick (Hamrick 1992) and its linkage to the ERDC-CHL-CMS hydrodynamic model. SNL-EFDC simulates flow and transport of sediment as bedload and suspended load. SNL-EFDC-SEDZLJ improves EFDC with updated sediment kinetics subroutines. Sediment erosion is calculated using data collected with a Sediment Erosion at Depth flume (SEDflume). SEDflume measures erosion rates as a function of shear stress and depth from relatively undisturbed cores taken directly from the sediment bed below the water body of interest. The use of SEDflume data provides more accurate sediment erosion rates that are directly input to the model.

15 Sep 2023

Real-Time Forecasting Model Development Work Plan

Abstract: The objective of the Lowermost Mississippi River Management Program is to move the nation toward more holistic management of the lower reaches of the Mississippi River through the development and use of a science-based decision-making framework. There has been substantial investment in the last decade to develop multidimensional numerical models to evaluate the Lowermost Mississippi River (LMMR) hydrodynamics, sediment transport, and salinity dynamics. The focus of this work plan is to leverage the existing scientific knowledge and models to improve holistic management of the LMMR. Specifically, this work plan proposes the development of a real-time forecasting (RTF) system for water, sediment, and selected nutrients in the LMMR. The RTF system will help inform and guide the decision-making process for operating flood-control and sediment-diversion structures. This work plan describes the primary components of the RTF system and their interactions. The work plan includes descriptions of the existing tools and numerical models that could be leveraged to develop this system together with a brief inventory of existing real-time data that could be used to validate the RTF system. A description of the tasks that would be required to develop and set up the RTF system is included together with an associated timeline.

13 Sep 2023

Sensitivity of Sediment Transport Analyses in Dam Removal Applications

Abstract: Dam removal has become a widespread river management practice in the US for a variety of goals including ecosystem restoration, removing aging infrastructure, flood risk management, and recreation. The ability to forecast the sediment impacts of dam removal is critical to evaluating different management alternatives that can minimize adverse consequences for ecosystems and human communities. Tullos et al. (2016) identified seven Common Management Concerns (CMCs) associated with dam removal. Four of these CMCs; degree and rate of reservoir sediment erosion, excessive channel incision upstream of reservoirs, downstream sediment aggradation, and elevated downstream turbidity are associated with stored sediment release and changing fluvial hydraulics. There are a range of existing qualitative and quantitative tools developed to infer or quantify geomorphic implications of disturbances like these in river environments (McKay et al. 2019). This study investigated how a one-dimensional (1D) sediment transport model can inform these four CMCs, develop an approach for assessing sediment transport model sensitivity in the context of the Simkins Dam removal, and use sensitivity analyses to identify key uncertainties, which can inform data collection and model building for other dam removal projects. For the selected case study, model outputs including the mean effective invert change (MEIC) and eroded sediment volume from reservoir were highly sensitive to the variation of the reservoir sediment gradation and sorting method selection. These model outputs also showed some sensitivity to the selected transport functions. Erosion method sensitivity using the channel evolution method will vary depending on side slope and channel parameter selection.

31 Aug 2023

Effects of Sedimentation on Three Hawaiian Coral Species under Laboratory Conditions

Abstract: Sedimentation can occur near a dredge operation in pulses over days, and potentially impact coral reefs occurring in close proximity. To improve the ability to predict the effects of dredging on corals, the effects of sedimentation in two 18-day experiments were studied for three common coral species representing different morphologies. In a laboratory setting, coral fragments were exposed to four sedimentation concentrations dosed every four days ranging from 0 to 60 mg cm-2. Separate experiments were performed in series, once with fine grain sediment and repeated with a coarse grain sediment. A 30-day sediment free observation period followed each experiment. Coral responses were measured throughout the experiment and at the end of the 18-day exposure and 30-day sediment free observation period. Photosynthetic yield, lipid ratios, tissue color, tissue loss, growth, and sediment cover varied among the treatment groups. All coral species were minimally affected when sediment concentrations were at or below 6 mg cm-2. P. meandrina and P. lobata experienced the most sediment coverage and tissue loss when exposed to sediment concentrations >30 mg cm-2 for either sediment. M. capitata experienced no sediment coverage or tissue loss when exposed to either sediment, but a reduction in photosynthetic yield at 60 mg cm-2 fine grain sediment was observed. During the 30-day post-exposure sediment free observation period, P. meandrina tissue loss continued, P. lobata nearly completely regrew lost tissue, while M. capitata showed no lingering effects. This study improves the US Army Corps of Engineers (USACE) ability to estimate the impacts of dredging on coral reefs.

24 Aug 2023

Houston Ship Channel Numerical Model Update and Validation

Abstract: The Houston Ship Channel (HSC) is one of the busiest deep-draft navigation channels in the United States and must be able to accommodate increasing vessel sizes. The US Army Corps of Engineers, Galveston District (SWG), requested the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, update and revalidate a previously developed three-dimensional Adaptive Hydraulics (AdH) hydrodynamic and sediment model of the HSC, Galveston, and Trinity Bays. The model is necessary for analyzing potential impacts on salinity, sediment, and hydrodynamics due to alternatives designed to reduce shoaling in the HSC. SWG requested an updated validation of the previously developed AdH model of this area to calendar years 2010 and 2017, utilizing newly collected sediment data. Updated model inputs were supplied for riverine suspended sediment loads as well as for the ocean tidal boundary condition. The updated model shows good agreement to field data in most conditions but also indicates potential issues with freshwater flow inputs as well as the ocean salinity boundary condition.

7 Aug 2023

Acoustic Doppler Current Profiler Study of Water and Sediment Movement through a Deep Scour Hole in the Lower Mississippi River

Abstract: A series of acoustic Doppler current profiler (ADCP) transects were collected through a deep scour hole at the bend near River Mile 60 on the Lower Mississippi River. The measurements were collected during both a low and a high flow. The ADCP results show a 3D flow field through the deep bend. The backscatter intensity of the ADCP measurements indicates the majority of the sediment remains close to the inside of the bed and high in the water column, with minimal concentrations at the bottom of the bend. These findings have implications for numerical sediment transport models, which tend to deposit material at the bottom of deep scour holes like the one in this study

7 Jul 2023

Geomorphic Assessment of the St. Francis River: Between Wappapello Lake and Lake City

Abstract: The St. Francis River is a complex system that lies in the historic floodplain of the Mississippi and Ohio Rivers. The basin has undergone extensive anthropogenic modifications, including reservoir construction, large-scale channelization, and construction of leveed floodways. Several analyses of available gage data, lidar data, and historical research have provided a picture of geomorphic trends and an overall understanding of the river’s stability. The types of analysis used to determine trends included yearly low stage plots, stage-duration curves, specific gage analysis, water surface slopes, and stream power changes. The results from these analyses were synthesized to develop an overall assessment of the reach. Channel cutoffs resulted in a significant decrease in channel length and sinuosity and triggered geomorphic change throughout the river. Immediately following channelization, dramatic decreasing trends in stage were observed for Fisk and Dekyn’s Store, while St. Francis and Holly Island began to aggrade. Slopes and stream power were significantly increased for the upper portion of the study area and showed a decreasing trend for the lower reach.