MMS ENVIRONMENTAL STUDIES PROGRAM: ONGOING STUDIES
MMS OCS Region: Headquarters
Title: Biological Characterization/Numerical Wave Model Analysis within Identified Borrow Sites Offshore the Northeast Coast of Florida (NT-05-05)
Total Cost:

$524K

 Period of Performance:

FY 2005-2007
Conducting Organization:

Scientific Environmental Applications, Inc.
MMS Contact:

Colleen Finnegan
Description:
Background

In Fiscal Year 2003, the Florida Geological Survey, in cooperation with MMS, began conducting  research to evaluate potential offshore sand resources for beach restoration along portions of Florida’s northeast coast.   This includes the offshore area along Nassau, Duval, St. Johns, Flagler and Volusia Counties.  More than 30 percent of the 148 shoreline miles in this study area is classified as Critical Eroding.   The primary focus is on the area extending from 3 to 8 miles offshore. 

Florida's eastern coastline is in a state of constant change.  Natural forces which impact this coastline include waves, wind, and a probable rise in sea level.   These forces are especially active in the winter months when nor'easters commonly sit offshore for days at a time which, together with high tides, results in severe beach erosion. The presence of numerous inlets, structures, and complex topography in certain areas certainly influences local wave, current, and sediment transport patterns. Wave modeling and sediment transport potential computations performed for MMS to assess the significance of impacts that would result from dredging sand at proposed sites offshore the central eastern coast of Florida determined that certain volumes of extractions from within sites offshore St. Lucie Inlet and offshore from Cape Canaveral could result in significant increases in wave heights as waves propagate over these areas. (Kelly et al, 2001). The same conditions may exist for areas along the northeast coast of Florida.  In addition, for previous NEPA assessments offshore Florida, little or no site-specific biological information has been available to use during the required environmental evaluations.

Objectives
The purpose of the study is to address environmental concerns, prior to actual dredging of the identified sand resource areas, the likelihood of adverse environmental impacts on resident biological organisms and on the local wave climate and sediment transport regime from sand dredging for the purposes of beach renourishment. The information provided from this study will be used to prepare environmental analyses to meet the requirements of current environmental laws and legislation and incorporate results, as appropriate in lease requirements for the dredging of OCS sand.
Methods

Biological: To evaluate the possible biological impacts associated with dredging, the present condition of benthic and fish assemblages will be characterized and interpretations will be developed to assess those impacts. The characterization of benthic communities will be done using existing literature, collection of field data and laboratory analysis. Grab samples, trawls, sediment profiling cameras, water column profiles and other current sampling techniques will be used to characterize the benthic biology in the field.  The structure of benthic communities and fish assemblages will be analyzed for diversity, evenness, species richness, biomass, taxonomic composition, gut content, and secondary production, etc.  Community cluster analysis will be performed as well. An evaluation of the potential environmental impacts to the biological community will be conducted by making inferences and interpretations based on the field data, laboratory analysis, historical information, past studies and the most recent scientifically accept theories and models.

Physical: To evaluate the possible physical impacts associated with dredging of identified borrow sites, and to examine on a generic basis, the possible effects of dredging along the west Florida shelf, wave transformation modeling and sediment transport potential calculations will be performed for 1) present existing conditions, and 2) present conditions with the proposed excavations sand from the identified borrow sites. Comparison of computations for existing and post-dredging conditions illustrate the relative impact of borrow site excavation on wave-induced coastal processes. Nearshore wave heights and directions along the shoreline landward of the proposed borrow site will be estimated using a state-of-the-art spectral wave model (STWAVE  or SWAN), which will be used to simulate the propagation of offshore waves to the shoreline.    Offshore wave data, available from offshore wave buoys maintained by the National Data Buoy Center (NDBC) will be used to derive input wave conditions for the model used.

Importance to MMS
The State of Florida and local jurisdictions will certainly be requesting negotiated agreements from the MMS for the use of OCS sand resources offshore the northeast coast for beach nourishment, especially as resources in State waters run dry. One such area in Federal waters has already been used to renourish Jacksonville Beach. The information gathered from this study is crucial in properly undertaking the required environmental assessments for proposed site-specific beach nourishment projects and will be used in developing/incorporating environmental stipulations in negotiated leases to protect the environment.
Current Status: The initial biological cruise has been completed and benthic and fish samples and surveys were successfully completed in November 2005. The second biological sampling cruise will take place in Summer 2006. Numerical modeling has commenced with the preparation of the modeling grids. A report synthesizing available biological and physical information has also been completed.
Final Report Due:

October 2007
Publications:
Affiliated WWW Sites: http://www.mms.gov/sandandgravel/Floridastudies.htm
Revised date:

February 2006
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