9 Oct 2024

Performance of High-Resolution, Acoustic Mapping Systems in a Fluid-Mud Environment : Testing the Effectiveness and Viability of High-Resolution, Hydrographic Survey Systems in a Fluid-Mud Environment

Abstract: This study explores the use of high-resolution acoustic mapping systems to penetrate fluid-mud layers by quantitatively relating depth with operating frequency. Prior to this study, multibeam surveys have proven be an effective method to elucidate the seafloor and collect bathymetric data on various bodies of water including rivers, lakes, bays, and the oceans. These techniques are regularly used on US Army Corps of Engineers dredged and federally maintained navigation channels. The objective of the study was to test the effectiveness of commercial off-the-shelf, low-frequency, high-resolution acoustic survey systems to penetrate fluid mud and if so, determine the density at penetration. The testing method combined multibeam echosounder, sub-bottom profiler, and single-beam echo sounder. In addition, in situ testing was conducted to determine the density of fluid-mud layers using a RheoTune profiler and laboratory testing. Results indicate that the use of currently available, bathymetric mapping systems operating at 90 kHz and higher are incapable of penetrating fluid mud in riverine and coastal shallow water conditions. This study demonstrates that while multibeam technology is effective at penetrating the water column, current frequencies available on the market are unable to penetrate fluid-mud layers in a riverine and shallow-water environment.

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).

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.

27 Jul 2022

Environmental Effects of Sediment Release from Dams: Conceptual Model and Literature Review for the Kansas River Basin

PURPOSE: Passing sediment from reservoirs to downstream channels is a potential solution to aging infrastructure and reservoir storage capacity loss, which is a pressing challenge nationwide. The US Army Corps of Engineers (USACE) sediment management actions at reservoirs such as flushing may drive ecological changes that may be beneficial or detrimental to downstream ecosystems. However, these potential effects are currently not well understood or documented. An exploratory study of the potential ecological effects of releasing sediment downstream from reservoirs is presented in this technical note (TN). We focus on Tuttle Creek Reservoir in Kansas and use fish species as indicators of ecological change. A literature review of Kansas fishes was conducted and three conceptual models illustrating potential benefits or negative effects of releasing sediment downstream of Tuttle Creek Reservoir was developed. Some fish species may benefit from sediment releases, while others may be negatively affected. Further research and tools are needed to develop a greater understanding of these effects.

24 Aug 2021

Spatial Distribution and Thickness of Fine-Grained Sediment along the United States Portion of the Upper Niagara River, New York

Abstract: Over 220 linear miles of geophysical data, including sidescan sonar and chirp sub-bottom profiles, were collected in 2016 and 2017 by the US Army Corps of Engineers and the US Fish and Wildlife Service in the upper Niagara River. In addition, 36 sediment grab samples were collected to groundtruth the geophysical data. These data were used to map the spatial distribution of fine-grained sediment, including volume data in certain locations, along the shallow shorelines of the upper Niagara River. Overall, the most extensive deposits were spatially associated with either small tributaries or with man-made structures that modified the natural flow of the system. Extensive beds of submerged aquatic vegetation (SAV) were also mapped. Although always associated with a fine-grained matrix, the SAV beds were patchy in distribution, which might reflect subtle differences in the grain size of the sediment matrix or could simply be a function of variations in species or growth. The maps generated from this effort can be used to guide sampling plans for future studies of contamination in fine-grained sediment regions.

8 Jul 2021

Effects of Geologic Outcrops on Long-Term Geomorphic Trends: New Madrid, MO, to Hickman, KY

Abstract: The Mississippi River between New Madrid, MO, and Hickman, KY, is of particular interest because of divergent trends in water surface profiles at the upstream and downstream ends of the reach. This report documents the investigation of the bathymetry, geology, and hydraulics of this segment of the river. The report shows that the area near River Mile 901 above Head of Passes strongly affects the river stages at low flows. This part of the river can experience high shear stresses when flows fall below 200,000 cfs, as opposed to most other locations where shear stress increases with flow. One-dimensional hydraulic modeling was also used to demonstrate that an increase of depth at a single scour hole, such as the one downstream from Hickman near River Mile 925, is unlikely to cause reach-wide degradation.

25 May 2021

Applying Resilience Concepts to Inland River Systems

Abstract: As environmental uncertainty increases, incorporating resilience into project assessments, research recommendations, and future plans is becoming even more critical. This US Army Engineer Research and Development Center special report (SR) demonstrates how the concepts of resilience can be applied in a uniform framework and illustrates this framework through existing case studies on large inland river systems. This SR presents the concepts of resilience in inland river systems, the application of these concepts across disciplines, basic parameters of a resilience assessment, and the challenges and opportunities available for incorporating a more holistic approach to understanding resilience of the US Army Corps of Engineers mission areas on inland rivers. Finally, these concepts are demonstrated in several case studies in the United States to exemplify how these parameters have been applied to improve the overall performance of the system.

21 May 2021

Approaches for Assessing Riverine Scour

Abstract: Calculating scour potential in a stream or river is as much a geomorphological art as it is an exact science. The complexity of stream hydraulics and heterogeneity of river-bed materials makes scour predictions in natural channels uncertain. Uncertain scour depths near high-hazard flood-risk zones and flood-risk management structures lead to over-designed projects and difficult flood-risk management decisions. This Regional Sediment Management technical report presents an approach for estimating scour by providing a decision framework that future practitioners can use to compute scour potential within a riverine environment. This methodology was developed through a partnership with the US Army Engineer Research and Development Center, Hydrologic Engineering Center, and St. Paul District in support of the Lower American River Contract 3 project in Sacramento, CA.

29 Apr 2020

PUBLICATION NOTICE: Application of Chirp Acoustic Sub-Bottom Data in Riverine Environments: Identification of Underlying Rocky Hazards at Cape Girardeau, Missouri, and Thebes, Illinois

NOTE: A revised version of the report MRG&P Report No. 31 has been published. While the link below remains valid, the PDF attached to the record is new. It is now 47 pages instead of 45 pages after the changes made. Please update your records as needed.

29 Apr 2020

PUBLICATION NOTICE: Lake Providence to Old River Geomorphology Assessment

Abstract: This report integrates information from previous geomorphic studies coupled with new analysis to provide a comprehensive geomorphic characterization of the Lake Providence (River Mile [RM] 487.2 Above Head of Passes [AHP]) to Old River Control Complex, (RM 317 AHP) reach from the early-1800s to present. Individual components of this study included the following: historical geomorphic studies, development of an events timeline, specific gage records, stage and flow duration trends, trends in water surface slopes, bed material studies, suspended sediment data, channel geometry data, and effects of channel improvement features (cutoffs, dike, revetment, and dredging). These individual assessments were consolidated to develop an overall assessment of how the study reach has evolved since the early-1800s.