3 Jun 2021

Elevation of underlying basement rock, Ogdensburg Harbor, NY

Abstract: Over six linear miles of shallow acoustic reflection geophysical data were collected in an 800 ft by 300 ft survey region at Ogdensburg Harbor, Ogdensburg, NY. To better accommodate modern commercial vessels and expand the harbor’s capacity, the current navigable depth of -19 ft Low Water Depth (LWD) needs to be increased to -28 ft LWD, and an accurate map of the nature of the riverbed material (e.g., unconsolidated sediment, partially indurated glacial till, or bedrock) is required to effectively plan for removal. A total of 28 boreholes were previously collected to map the stratigraphy, and the effort revealed significant spatial variability in unit thickness and elevation between adjacent boreholes. To accurately map this variable stratigraphy, chirp sub-bottom profiles were collected throughout the region, with an average line spacing of 13 ft. These sub-bottom data, validated and augmented by the borehole data, resulted in high-resolution spatial maps of stratigraphic elevation and thickness for the study area. The data will allow for more accurate assessment of the type and extent of different dredging efforts required to achieve a future uniform depth of -28 ft LWD for the navigable region.

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.

12 May 2021

Automated Characterization of Ridge-Swale Patterns Along the Mississippi River

Abstract: The orientation of constructed levee embankments relative to alluvial swales is a useful measure for identifying regions susceptible to backward erosion piping (BEP). This research was conducted to create an automated, efficient process to classify patterns and orientations of swales within the Lower Mississippi Valley (LMV) to support levee risk assessments. Two machine learning algorithms are used to train the classification models: a convolutional neural network and a U-net. The resulting workflow can identify linear topographic features but is unable to reliably differentiate swales from other features, such as the levee structure and riverbanks. Further tuning of training data or manual identification of regions of interest could yield significantly better results. The workflow also provides an orientation to each linear feature to support subsequent analyses of position relative to levee alignments. While the individual models fall short of immediate applicability, the procedure provides a feasible, automated scheme to assist in swale classification and characterization within mature alluvial valley systems similar to LMV.

12 May 2021

Channel Assessment Tools for Rapid Watershed Assessment

Purpose: Existing Delta Headwaters Project (DHP) watershed stabilization studies are focused on restoration and stabilization of degraded stream systems. The original watershed studies formerly under the Demonstration Erosion Control (DEC) Project started in the mid 1980s. The watershed stabilization activities are continuing, and because of the vast number of degraded watersheds and limited amount of yearly funding, there is a need for developing a rapid watershed assessment approach to determine which watersheds to prioritize for further work. The goal of this project is to test the FluvialGeomorph (FG) toolkit to determine if the Rapid Geomorphic Assessment approach can identify channel stability trends in Campbell Creek and its main tributary. The FG toolkit (Haring et al. 2019; Haring et al. 2020) is a new rapid watershed assessment approach using high-resolution terrain data (Light Detection and Ranging [LiDAR]) to support U.S. Army Corps of Engineers (USACE) watershed planning. One of the principal goals of the USACE SMART (Specific Measureable Attainable Risk-Informed Timely) Planning is to leverage existing data and resources to complete studies. The FG approach uses existing LiDAR to rapidly assess either reach-specific analysis for smaller more focused studies or larger watersheds or ecosystems. The rapid assessment capability can reduce the time and cost of planning by using existing information to complete a preliminary watershed assessment and provide rapid results regarding where to focus more detailed study efforts.

30 Apr 2021

Empirical analysis of effects of dike systems on channel morphology of the Lower Mississippi River

NOTE: There was an title error in MRG&P Report No. 36, which was published 3/2/2021 . A new PDF has been attached to the record with the correct title. This email has the correct title as well. No other changes were made.

1 Oct 2020

Framework Geology of Cape Shoalwater and Northwest Willapa Bay, Washington: Assessing Potential Geologic Impacts on Recent Shoreline Change

Abstract: The shoreline along Cape Shoalwater and northwest Willapa Bay has experienced the highest rates of erosion along the entire Pacific Coast of the United States, due in part to rapid northward migration of the navigation channel. Recently, channel migration and shoreline erosion in this region have slowed, but the cause of this relative stabilization, and thus the longevity of these new patterns, is unknown. Given the complex neotectonics and geologic framework of the southern coast of Washington, it is possible that underlying, erosion-resistant geologic units have become exposed along the channel and/or in the nearshore, and are acting to reduce or halt channel migration and/or shoreline erosion. Conversely, the apparent reduction may be due to subtle, short-term changes in regional hydrodynamics and/or sediment transport, and thus future rates of channel migration and/or shoreline erosion might increase back to historical rates. The purpose of this special report is to detail the geologic and neotectonic framework of the northern Willapa Bay region, and determine how the underlying framework geology might be impacting channel stability and adjacent shoreline erosion rates. Suggested research questions to quantify potential geologic control are also presented, including the potential benefits of the research to the district.