The landward limit of surveys along the western shore was the low tide line or the railroad tracks that extend up the west shore of the estuary whichever is most eastward on a given line of latitude except for tidal portions of tributaries such as the Binnen Kill north of Interstate 90 and Catskill Creek north of Bridge Street. The landward limit of surveys along the eastern shore of the estuary was the low tide line or the railroad tracks that extend up the east shore of the estuary whichever was most westward on a given line of latitude including Schodack Creek north to Little Schodack Island. Geographic limits of the project survey covered some or all shallow areas of the estuary from the Verrazano Narrow Bridge north to the federal dam at Troy. This primary goal of this project, guided by NYSDEC, was to acquire acoustic data in the shallow water areas of the estuary that would facilitate classification of the substrate into biologically significant units. Pilot studies (Maher, 2006 Strayer et al., 2006 Yeung and McConnaughey 2008) have indicated that variations in remote sensing acoustic data are strongly correlated to variations in benthic macro invertebrate communities. Utilizing advanced technology and the experience of the previous benthic mapping projects, this project provided NYSDEC maps of the shallow areas that were not addressed with the previous studies. About a third of the estuary was not surveyed this third is the area that is home to important submerged aquatic vegetation (SAV) beds which sustain much of the biologic community in the estuary. Previous work in the Estuary was limited, in that detailed bathymetry was not acquired in areas of the estuary shallower than about 4 meters due to financial constraints. To conserve for future generations the rich diversity of plants, animals and habitats that are key to the vitality, natural beauty and environmental quality of the Hudson River Valley. To conserve, protect, and, where possible, enhance critical river and shoreline habitats to assure that the life cycles of key species are supported for human enjoyment and to sustain a healthy ecosystem. This project was being conducted as part of the Hudson River Estuary Action Plan promulgated by NYSDEC and approved by the Governor in 1996 which committed the State to, among other things, -Conduct a submerged habitat inventory to define areas most in need of protection for Hudson River fish, blue crab, and food chain species. In addition NYSDEC requested the collection of grab samples and 100 sediment cores at least one meter in length distributed throughout the same shallow portions of the Estuary. Points were exported from the raw XTF files at an interval of 400 pings (approximately 100 meters).Ĭontact Org: Hudson River National Estuarine Research Reserve, NYS DECĮmail: work was consistent with the Statement of Work prepared by the New York State Department of Environmental Conservation (NYSDEC) to develop detailed bathymetric maps, acoustic reflectivity and acoustic character maps of the shallow portions of the Hudson River Estuary from the Verrazano Narrows north to the federal dam in Troy. Raw XTF files were created by converting Hypack format (*.HSX) into Triton format (*.XTF). Backscatter data processing was completed with CARIS 7.0.
Additionally, Fugro provided slope, aspect and hillshade models as additional acoustic parameters. Reflectivity data from the GeoSwath was used to produce a normalized as well as a classified image of the bottom.
HYPACK MAP LANES FOR SIDE SCAN FULL
Fugro's system measured and recorded acoustic reflectivity that has a high dynamic range such that the full range of reflectivity's encountered in the estuary environment can be recorded while maintaining a constant gain setting on the system receiver. Data Collection and Processing: The interferometric system used to measure acoustic reflectivity, provided a quantitative measure of reflectivity for every square meter of the survey area. Sonar data were collected November 6 to December 15, 2009, in the estuary north from Saugerties to Troy. These points correspond to individual pings which produced hte side-scan-sonar backscatter imagery. Side-Scan-Sonar Points for Hudson River, NY