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.

25 May 2023

Geomorphic Feature Extraction to Support the Great Lakes Restoration Initiative’s Sediment Budget and Geomorphic Vulnerability Index for Lake Michigan

Purpose: This Coastal and Hydraulics Engineering technical note (CHETN) details a Geographic Information Systems (GIS) methodology to produce advanced lidar-derived datasets for use in a coastal erosion vulnerability analysis conducted by the US Army Corps of Engineers (USACE) and other federal partners for the Great Lakes Restoration Initiative (GLRI).

1 Dec 2022

Evaluation of Cedar Tree Revetments for Bank Stabilization at the Locust Creek Conservation Area, Missouri: Quantifying Bank Erosion Volumes from Preproject to Postfailure

Abstract: The US Army Corps of Engineers Regional Sediment Management (RSM) program funded research to assess the longevity and effectiveness of cedar tree revetments for sediment reduction. Between 1988 and 1997, the Missouri Department of Conservation (MDC) constructed multiple cedar tree revetments, plantings, and a grade-control structure at an experimental stream management area on Locust Creek within the Locust Creek Conservation Area (LCCA). For the first few years, MDC also replaced missing trees as needed. MDC monitored these sites with photographs and cross sections until 2004. This study evaluated bank stability on Locust Creek from 1970 to 2019 using aerial imagery, lidar, ground surveys, and a December 2019 site visit to estimate the areal change in streambanks and the volume of sediment eroded over the years. Based on their dates of construction, the project compared preproject, with-project, and postfailure conditions at each site. The project included cedar tree revetments, other hardwood revetments, plantings, and a grade-control structure. This research found a 50% to 64% reduction in erosion for approximately 14 years. As of December 2019, all tree revetments had failed, and banks were bare and steep. The grade-control structure remained intact and continued to stabilize bed and banks immediately upstream.

13 Sep 2022

Sediment Mobility, Closure Depth, and the Littoral System – Oregon and Washington Coast

Abstract: Forty years ago, the depth of closure concept was introduced to provide a systematic, process-based approach to evaluate seasonal changes in cross-shore profiles and sediment mobility in the nearshore. This study aims to extend that theory by directly considering wave-asymmetry in the nearshore environment. This technical note introduces a methodology to calculate wave induced dispersal of dredged material placed in nearshore sites and summarizes analyses validating the approach using data from the South Jetty Site at the Mouth of the Columbia River. This investigation highlights the notion of a cross-shore gradient in nearshore placement effectiveness of dredged material that can assist project managers plan and execute sustainable sediment management practices at coastal inlets.

31 Aug 2022

Sediment Supply from Bank Caving on the Lower Mississippi River, 1765 to Present

Abstract: Bank caving rates and associated total sediment supply were calculated along the Lower Mississippi River from Cairo, IL, to Baton Rouge, LA, using historical maps between 1765 and 1992. Comparison of these maps reveals that the added sediment loads from bank erosion have greatly declined through time. In the pre-1960s period, erosion rates generally ranged from approximately 300 million cubic yards (MCY) to 400 MCY, with the 1880–1930s period having the highest erosion rates of approximately 600 MCY. By the 1990s, the sediment supply from bank erosion was essentially eliminated, with significant erosion being observed at only a few locations, totaling approximately 40 MCY/year. This equates to approximately a 90% reduction in the amount of total sediment being supplied to the channel system from bank erosion.

31 Aug 2022

Current State of Practice of Nearshore Nourishment by the United States Army Corps of Engineers

Abstract: This US Army Corps of Engineers (USACE) special report prepared by the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, provides an overview of the current state of practice for nearshore nourishment with dredged sediment. This special report was completed with responses and input from professionals across the dredging and placement teams from each of the USACE Coastal and Great Lakes districts, providing comprehensive overviews of the decision trees these districts utilize in the placement of their dredged sediment. This report describes the general practice of nearshore nourishment, the impediments and concerns faced by nearshore nourishment projects, and the practical methods utilized by the Coastal and Great Lakes districts for their nearshore nourishment projects. Understanding the current state of practice, along with the general and specific impediments the districts face, enables further research in and development of best practices for use across the USACE and better communication of the practice to other stakeholders.

19 Aug 2022

The Old River, Mississippi River, Atchafalaya River, and Red River (OMAR) Technical Assessment

NOTE: The Old River, Mississippi River, Atchafalaya River, and Red River (OMAR) Technical Assessment is a 9-volume series of reports that was produced under the direction of the Mississippi River Geomorphology & Potamology Program. An abstract from the main report, Volume 1, is listed below, along with the individual volume titles and links to the relevant reports. ABSTRACT: This is the main report of Old River, Mississippi River, Atchafalaya River, and Red River (OMAR) Technical Assessment. The primary objective of the OMAR Technical Assessment was to conduct a comprehensive evaluation that aimed to understand the impacts of former and potential changes to the system in the vicinity of the Old River Control Complex (ORCC) over time, the water and sediment delivery regime at the ORCC, and the effects to the river system surrounding the ORCC. Scenarios evaluated in this technical assessment were designed to investigate potential system responses to a wide range of possible operational alternatives and identify knowledge gaps in current understanding of system behavior. This report summarizes and synthesizes the individual reports detailing the investigations into specific aspects of the ORCC and the surrounding region.

29 Jul 2022

Investigation of Sources of Sediment Associated with Deposition in the Calcasieu Ship Channel

Abstract: The Calcasieu Ship Channel (CSC) is a deep-draft federal channel located in southwest Louisiana. It is the channelized lowermost segment of the Calcasieu River, connecting Lake Charles to the Gulf of Mexico. With support from the Regional Sediment Management Program, the US Army Corps of Engineers, New Orleans District, requested that the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, perform an investigation of the potential sources of sediment associated with dredging in the CSC. A previous study had quantified sediment from known sources, indicating that the known sediment sources contribute approximately only 21% of the volume that is regularly dredged from the channel. This technical report details the results of the current study, which employed multiple methods, including numerical analysis, to identify potential additional sources of sediment by first examining the available literature and the modeled energetics and flow pathways, and then estimating the quantities of sediment associated with these identified sources that may be contributing to the shoaling of the CSC. The results of these efforts were used to update the original sediment budget with estimates of the contributions from two additional sources: the erosion of interior wetlands and coastally derived sediments.

29 Jul 2022

Sediment Provenance Studies of the Calcasieu Ship Channel, Louisiana

Abstract: To maintain the navigability of the Calcasieu Ship Channel (CSC), the US Army Corps of Engineers annually dredges millions of cubic yards of sediment from the inland channel. To assess sources of channel shoaling, a previous study examined river and bankline erosion as inputs. Results from that study accounted for approximately 20% of dredged volumes. Through the support of the Regional Sediment Management Program, a follow-up investigation reviewed prior sediment budgets, identified potential missing sediment sources, modeled potential sediment pathways, and utilized geochemical fingerprinting to discern primary shoaling sources to the channel. The missing sediment sources from the original budget include coastally derived sediment from the Gulf of Mexico and terrestrially derived sediment from Lake Calcasieu and surrounding wetlands. Results from geochemical fingerprinting of various potential sediment sources indicate the Calcasieu River and the Gulf of Mexico are primary contributors of sediment to the CSC, and sediments sourced from bankline erosion, Lake Calcasieu bed, and interior wetlands are secondary in nature. These results suggest that engineering solutions to control shoaling in the CSC should be focused on sources originating from the Gulf of Mexico and river headwaters as opposed to Lake Calcasieu, channel banklines, and surrounding wetlands

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.