Develop Accurate Methods for Characterizing and Quantifying Cohesive Sediment Erosion Under Combined Current-Wave Conditions
ER-1497
Objective
Sediment Erosion Actuated by Wave Oscillations and Linear Flow (SEAWOLF) Flume
Aquatic fine-grained cohesive sediments are often the final receptor of contaminants released by Department of Defense (DoD) activities or of contaminants that migrate to DoD facilities. In estuaries, harbors, and channels, contaminated sediments can be mobilized and transported by the combined action of relatively steady currents (forced by river flow, tides, and wind) and, to an even greater extent, by the larger, unsteady bottom shear stresses associated with higher frequency oscillatory wave motions (either wind- or vessel-generated). Methods to measure contaminated sediment stability and erosion as influenced by wave processes is critical to assessing contaminant fate and associated risk. These measurements are also critical in evaluating the benefits of various remediation options including removal, monitored natural recovery, and capping.
The objective of this project is to develop methods to reliably measure and predict erosion of contaminated fine-grained sediments under bottom shear stress conditions that represent combined wave and current action. The shear stress conditions will replicate those expected in the field (non-breaking wave, shallow water, estuarine, harbor, and coastal environments). Specific objectives include: (1) calibrate and validate an innovative mobile erosion flume designed to measure cohesive sediment erosion and erosion variation with depth below the original sediment bed surface for combined wave-current conditions; (2) develop algorithms for estimating erosion rate as a function of current and wave parameters, such as current velocity, wave height, and wave period; (3) explore the validity of using an equivalent steady shear stress to represent time-varying wave-current shear stress; and (4) quantify uncertainty for erosion rate measurements and calculations.
Technical Approach
In this project, researchers will focus on calibrating and verifying the applicability of a prototype flume designed to measure erosion of fine-grained, cohesive sediment and the variation of erosion with depth below the original sediment bed surface under combined unidirectional and superimposed oscillatory bottom shear stress. These are similar to the shear stress conditions that exist in wave-current environments. The new flume is based on the design of a well-documented, frequently used flume for measuring cohesive sediment erosion under unidirectional flow. Preliminary results using the prototype flume for the combined unidirectional and oscillatory flow have been published and are promising for successful development and application of the flume as a field device for measuring erosion rates under wave-current conditions.
Benefits
This project will provide more accurate methods for assessing contaminated sediment stability. The methods developed for measuring and predicting contaminated sediment erosion variation with depth under wave-current conditions will be peer-reviewed, cost effective, and standardized. Such methods do not currently exist, adding significant uncertainty to predictions of contaminant fate and associated risk in shallow-water, coastal, estuarine, and harbor environments. This uncertainty presently complicates risk assessment and evaluation of remediation options. (Anticipated Project Completion - 2010)
Points of Contact
Principal Investigator
Dr. Joseph Gailani
USACE-ERDC
Phone: 601-634-4857
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.