Home / Media / News / NewsSearch
Results:
Tag: Sedimentation and deposition
Clear

  • Design of River Training Structures Using Isogeomorphic Constraints

    Abstract: Prepared for the Mississippi River Geomorphology and Potamology program of the United States Army Corps of Engineers (USACE), through the Coastal and Hydraulics Laboratory (CHL), this report introduces the concept of river control structure design using isogeomorphic constraints. The report defines isogeomorphic design methodology and demonstrates the application of the methodology using both analytic and numerical examples. The examples investigated herein are idealized, and application to real-world conditions (such as a dike-field) would be far more complex than what is demonstrated herein. This report merely serves as an introduction to a novel design paradigm that future studies can further investigate and refine with the ultimate objective of developing improved design guidance for USACE.

  • Measured and Projected Loss of Water Storage in 162 USACE Reservoirs due to Sedimentation: 1938–2074

    Sediment accumulation in reservoirs is a recognized global problem with serious implications for water-supply security, flood risk reduction, and hydropower generation. This Regional Sediment Management Technical Note (RSM-TN) aggregates water-storage volume data from a sample of 162 US Army Corps of Engineers (USACE) reservoir projects to provide the historic and current water-storage capacity at these projects. Future trends for water storage and sedimentation impacts are then predicted through the year 2074.

  • Gravel Investigations Informing Resource Management Within the Lower Mississippi River

    Abstract: This report integrates available information about gravel deposits within the Lower Mississippi River (LMR) from previous studies coupled with new analysis to identify reoccurring observed gravel locations. This study also summarizes spatial and temporal trends of bed material sediment characteristics, focusing primarily on gravel. Moreover, selected data sets from previous studies, and field and aerial observations have been added to a geographic information system (GIS) database housed in ArcPro to illustrate observed gravel locations. Last, a literature review documenting the ecological importance of gravel bars to riverine fauna and a brief discussion of potential technologies to support conservation efforts are included. Major findings summarized herein are (1) the presence of gravel deposits tend to decrease in a downstream direction along the LMR; (2) qualitative analyses of aerial videos suggest that gravel-predominant bars are more common between River Miles 953 and 681; (3) past investigations have documented gravel sizes at rivers bars ranging from pebbles to boulders; (4) the gravel content in LMR bed material samples has decreased since 1932; and (5) more detailed surveys are needed to better delineate the spatial extents and depth of gravel bars and identify suitable technology to detect potential buried gravel.

  • Numerical Modeling of Coastal Processes with Beneficial Use of Dredged Sediment in the Nearshore at Jekyll Island, Georgia

    Abstract: This report provides numerical model results to assist the US Army Corps of Engineers–Savannah District (SAS). These results evaluate beneficial use alternatives for the sediment from an advance maintenance widener of the Brunswick Harbor Entrance Channel between stations −14+000 and −28+000. This study applied a coastal wave, hydrodynamic and sediment transport model (Coastal Modeling System), and a shoreline change model (GenCade), focusing on developing and simulating placement alternatives. Subaerial placement model results indicate better shore and beach preservation than at the nearshore nourishment. Placing sediment closer to the “transition zone” between the revetment and natural beach will increase the volume of sand that remains in that area. Some sediment is predicted to return to the channel, but these volumes are small fractions of the placed material. GenCade results indicate that the transition zone rock debris decreases shoreline erosion. Removing it has less impact on that area than any of the subaerial nourishments, but this prediction does not include profile equilibration that may occur after the first 4 months. Overall, model results indicate that subaerial placement will have strong positive response at the eroding beach, and related increases to channel infilling rates are relatively small.

  • Corps Shoaling Analysis Tool (CSAT) User Guide

    Abstract: The Corps Shoaling Analysis Tool (CSAT) is a suite of computational routines for evaluating shoaling rates in navigation channels maintained by the US Army Corps of Engineers (USACE). This is achieved using survey data from the eHydro enterprise hydrographic survey database. At the local scale, CSAT’s outputs are useful for understanding historical shoaling trends and identifying shoaling hotspots, while enterprise-level shoaling forecasts support Operations and Maintenance (O&M) planning over a 5-year time horizon. This user guide provides practical, step-by-step instructions for new CSAT users who wish to download, install, and run the tool. Later sections provide insight into CSAT’s advanced features while also describing the methods and assumptions that underlie the calculations.

  • Review of Mississippi River Sediment-Sampling Protocols

    Abstract: The Mississippi River sediment data protocols located in the US Army Corps of Engineer (USACE), St Louis, Memphis, Vicksburg, and New Orleans Districts, were reviewed and evaluated. The review included both USACE and US Geological Survey (USGS) sampling sites. The purpose of this review was to evaluate the reported historical sediment data and to provide guidance for moving forward with an accurate and consistent sediment data collection program. The review was focused on the reliability of the reported historical data and its usefulness for use in sedimentation studies related to long-term aggradation, degradation, and dredging. Recommendations to implement effective sediment data collection, laboratory analyses, and reporting were provided.

  • Lower James River Sediment Transport Modeling: Jordan Point

    Abstract: US Army Corps of Engineers–Norfolk District (NAO) requested assistance from the US Army Engineer Research and Development Center (ERDC) to examine currently used placement sites within the James River, Virginia, initiative area, determine potential risk to critical environmental receptors during placement, and predict the life cycle of the placement sites. The focus of the analysis within this work is the Jordan Point placement site. The far-field, fate-transport modeling at Jordan Point shows relatively low maximum values of suspended sediment concentration (less than 40 mg/L) and deposition values (less than 0.2 cm). Material that is placed at Jordan Point appears to quickly disperse through the system, depositing in thin layers at specific areas. The life-cycle analysis performed for the Jordon Point placement site yielded an estimated useable project life of the Jordan Point placement sites of 26 years with an uncertainty of ±4 years. Analysis showed that 97% of the net sediment deposition in the navigation channel in proximity to this site is from the upper James River, 2% is from downstream sources, and 1% is from the two Jordan Point placement sites.

  • Validating Sediment Budgets Along the North Atlantic Coast Using the Updated Sediment Budget Calculator

    Purpose: This Regional Sediment Management (RSM) technical note (TN) outlines two case studies validating the Sediment Budget Calculator (SBC) using accepted values from the literature and published sediment budgets. Initially developed by the US Army Corps of Engineers (USACE) as a web-based tool, the SBC calculates all viable sediment transport rates for an inlet environment given user-defined inputs. The next-generation SBC was converted into Python 3.9 to make it more accessible than the original C++ version. These case studies outline the efficacy of the SBC tool for deriving accurate and reliable sediment budget values. Finally, the TN discusses future SBC improvements and efforts to incorporate SBC results into the Sediment Budget Analysis System (SBAS).

  • Cloud-Based Workflow to Process Regional Topobathymetric Lidar Datasets for Integrated USACE Shoaling Analyses

    Purpose: This Coastal and Hydraulics Engineering Technical Note (CHETN) details a methodology to process and format regional topobathymetric datasets for use in the US Army Corps of Engineers (USACE) Corps Shoaling Analysis Tool (CSAT).

  • Geomorphic Assessment of the St. Francis River Phase II

    Abstract: Significant sedimentation issues persist within the St. Francis Basin as a result of extensive drainage alterations. The objective of this study is to characterize the bed and bank sediment throughout the study reach and identify potential sources of sediment contributing to the sanding issues below Holly Island. The sedimentation below Holly Island increases the Memphis District’s maintenance needs in the St. Francis River Basin by requiring millions of dollars for channel cleanout and bank stabilization projects. This effort synthesizes prior geomorphic studies and existing survey data to break the study reach into seven geomorphic reaches of interest. Simultaneously, 151 bed samples and 137 bank samples were collected to characterize the sediments within the study reach to develop a data dictionary for future sediment budget development. Results show the St. Francis River is a poorly sorted, sand-bed river overlain by 10 to 20 feet of silts and clays along the banks. Iron Bridge to Highway U (Reach 1-3) may reach pseudo-stability so long as existing grade-control structures and bank stabilization features remain. Reach 6, between St. Francis and Brown’s Ferry, is evolving with one cutoff forming and one cutoff recently complete. This reach may be a source of sediment to downstream reaches.