Anthropogenic wastes, toxic chemicals, and changes in land-use patterns resulting from residential, commercial, and recreational development have stressed the environment of the Sound, causing degradation and potential loss of benthic habitats (Koppelman and others, 1976; Long Island Sound Study, 1994). Detailed maps of the sea floor are needed to help evaluate the extent of adverse impacts and to help manage resources wisely in the future. Therefore, in a continuing effort to better understand Long Island Sound, we have constructed and interpreted mulitbeam bathymetric data within specific areas of special interest. The gridded data presented herein covers a roughly 94 km square area of the sea floor in the area known as the Race at the eastern end of Long Island Sound. The original multibeam bathymetric data were collected during October 2003 as part of charting applications aboard the NOAA Survey Vessel Thomas Jefferson. A Simrad EM1002 multibeam system mounted on the hull of this vessel was used to acquire over 560 km of survey lines from the deeper water (>20 m) parts of the study area. Two 29-foot launches with hull-mounted Reson systems were deployed from the ship and were used to acquire an additional 637 km of survey lines from the shallower areas.
The detailed bathymetic data and their interpretations serve many purposes, including: (1) defining the geological variability of the sea floor, which is one of the primary controls of benthic habitat diversity; (2) improving our understanding of the processes that control the distribution and transport of bottom sediments and the distribution of benthic habitats and associated infaunal community structures; and (3) providing a detailed framework for future research, monitoring, and management activities. The bathymetric data models also serve as base maps for subsequent sedimentological, geochemical, and biological observations, because precise information on environmental setting is important for selection of sampling sites and for accurate interpretation of point measurements. This ArcGIS GRID layer represents a hill shade of the bathymetric grid H11250U. It was created with the sun at an azimuth of 315, altitude angle above the horizon of 30, and a verticle exaggeration (z factor) of 10.
U.S. Geological Survey, 2007, H11250U_HS: 2-m Hill-Shaded Bathymetric Grid of NOAA Survey H11250 of The Race (UTM, Zone 18): Open-File Report 2007-1012, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.This is part of the following larger work.Online Links:
- <http://pubs.usgs.gov/of/2007/1012/data/bathy/grids/utm/h11250_utm18_hlshd2m/h11250u_hs.zip>
- <http://pubs.usgs.gov/of/2007/1012/html/catalog.html>
Poppe, L.J., DiGiacomo-Cohen, M.L., Doran, E.F., Smith, S.M., Stewart, H.F., and Forfinski, N.A., 2007, Geologic Interpretation and Multibeam Bathymetry of the Sea Floor in the Vicinity of the Race, Eastern Long Island Sound: Open-File Report 2007-1012, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.Online Links:
This is a Raster data set. It contains the following raster data types:
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 2.000239
Ordinates (y-coordinates) are specified to the nearest 2.000239
Planar coordinates are specified in meters
The horizontal datum used is D_WGS_1984.
The ellipsoid used is WGS_1984.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257224.
Sequential unique whole numbers that are automatically generated.
Source data were acquired during National Oceanic and Atmospheric Administration (NOAA) survey H11250. Please acknowledge NOAA as the originator of the dataset from which this dataset was derived.
508-548-8700 x2314 (voice)
508-457-2310 (FAX)
lpoppe@usgs.gov
The purpose of this datalayer is to release a 2-m hill-shaded grid of NOAA survey H11250 in UTM18 from easternmost Long Island Sound and westernmost Block Island Sound. This GIS layer represents a hill shade of the bathymetric grid H11250U. It was created with the sun at an azimuth of 315, altitude angle above the horizon of 30, and a verticle exaggeration (z factor) of 10. This data set serves a starting point for a geologic study of the area surrounding the Race Long Island Sound. As interpretative layers and images are created they will be added to the GIS database. This gridded data can be used in ArcMap or ArcView to dramatically display the varied bathymetry and geologic features of the area.
National Oceanic and Atmospheric Administration, Unpublished Material, B370_03_H11250G_dtm2m_interp.gutm.
Person who carried out this activity:
(757) 441-6726 (voice)
shep.smith@noaa.gov
Data sources produced in this process:
Person who carried out this activity:
508-548-8700 x2280 (voice)
508-457-2310 (FAX)
cpolloni@usgs.gov
Data sources produced in this process:
Person who carried out this activity:
(860) 405-9210 (voice)
mdicohen@usgs.gov
Data sources produced in this process:
Person who carried out this activity:
860-405-9210 (voice)
mdicohen@usgs.gov
Data sources produced in this process:
Poppe, L.J., DiGiacom-Cohen, M.L., Smith, S.M., Stewart, H.F., and Forfinski, N.A., 2006, Seafloor character and sedimentary processes in eastern Long Island Sound and Western Block Island Sound: Geo-Marine Letters v. 26, p. 59-68.
The only attribute value represents hill-shaded gridded bathymetry - the grid should be displayed in shades of gray to give impression of a shadded relief map.
Navigation was by differential GPS; positional accuracy to less than 10 m.
All collected data were processed and used to generate the gridded data. The area is considered complete; the gaps in the data lie in areas inaccessible to the survey vessels (shallow water surrounding islands).
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Data are not to be used for navigation purposes.
Public domain data are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) and the Connecticut Department of Environmental Protection as the originators of this dataset.
508-548-8700 x2314 (voice)
508-457-2310 (FAX)
lpoppe@usgs.gov
Downloadable Data - H11250U_HS - ArcGIS grid format hillshaded bathymetry image
Although this data set has been used by the U.S. Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), and the Connecticut Department of Environmental Protection (CTDEP), no warranty, expressed or implied, is made by the USGS, NOAA, and the Connecticut DEP as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by these agencies in the use of these data or related materials.Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
| Data format: | One file (h11250u_hs.zip) containing the ArcInfo grid file components, browse graphic, and metadata. in format ARCG ESRI Raster Grid Size: 23.125 |
|---|---|
| Network links: |
<http://pubs.usgs.gov/of/2007/1012/data/bathy/grids/utm/h11250_utm18_hlshd2m/h11250u_hs.zip> <http://pubs.usgs.gov/of/2007/1012/html/catalog.html> |
| Media you can order: | DVD-ROM (Density 4.75 Gbytes) (format UDF) |
The user must have a program similar to ArcGIS that is capable of reading and processing the data files.
508-548-8700 x2314 (voice)
508-457-2310 (FAX)
lpoppe@usgs.gov
