Annex IV distributes metadata forms (questionnaires) to solicit information from researchers around the world who are exploring the environmental effects of marine renewable energy. This page provides a description and contact information related to the research. Content is updated on an annual basis.

Hydrographic and Sediment Field Surveys

Research Study Annex IV

Title: Hydrographic and Sediment Field Surveys
Start Date:
January 01, 2010
State:
Technology Type:
Info Updated:
April 02, 2018
Study Status: 
Completed
Princple Investigator Contact Information: 

Name: David Schlezinger

Address: 706 Rodney French Blvd., New Bedford MA 02744

Phone: +1 508-910-6314

Email: dschlezinger@umassd.edu

Project Description: 

The overarching goal of the project was to provide a detailed understanding of site-specific current velocity in the area of Muskeget Channel most likely to be used for tidal power generation as well as benthic information to support future siting decisions relative to various ocean renewal energy technologies, specifically:

  1. How do tidal currents vary spatially and temporally in the highest velocity zone of Muskeget Channel;
  2. What are the potential effects to benthic communities in the high velocity zone of Muskeget Channel due to scouring should tidal turbine technologies be deployed in this environment using moorings;
  3. How susceptible are tidal energy generators to bio-fouling and to what extent will the biofouling of generators and moorings drive changes in the local biology.
Funding Source: 

Department of Energy, Advanced Water Power Grants Program, FFY’10

Location of Research: 

Muskeget Channel, Edgartown Massachusetts

Project Progress: 

There was much interest in the site and the overall project, but funding was not avaliable to cable the site to shore. It is possible that work on this research study may begin again in the future.

Key Findings: 

Tidal elevation data provided precise water surface gradients through the study area. Since it is these gradients which are responsible for the high velocities seen in Muskeget Channel, the fine scale data will provide a valuable benchmark to assess future impacts when the hydrokinetic potential of the area is developed. In addition, the Pocha tide gauge suggested that this nearshore region being considered as a cable route may be more complicated than first supposed. Bathymetric surveys were completed for the developmentally viable portion of the channel proper and were both validated and augmented by the USGS Swath survey. Long term current measurements by bottom mounted ADCP indicated slightly higher velocities than predicted by extended cross channel velocity profiling and provides the basis for power production estimates using different technologies and deployment schemes. The region between Transect 6 and Transect 7 had the highest current velocities and the greatest water depths, ideal for addressing the compromise between navigation concerns and optimizing power generation. Deployment of the scouring block as a surrogate for large scale mooring weights indicated that despite the dynamic nature of the study area equilibrium conditions were reached relatively quickly. Furthermore, the area disturbed by the bottom structure was small extending no more than 1 diameter from the structure. Fouling studies were interrupted by Hurricane Irene and the arrays have yet to be found and recovered, however, the one untreated section retrieved showed fouling by algae but virtually no indication of faunal colonization. This work will need to be followed up in the future to accurately predict mooring longevity and maintenance schedules for power generators. The absence of extensive fouling may result from the lack of substantial naturally occurring hard structures in the region. Diver observations indicated the presence of sand waves and occasionally gravel associated with the troughs between the wave crests. Sidescan sonar surveys confirmed these general observations. Small high intensity returns did suggest the presence of some hard structures on the bottom, but these objects could not be identified.

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