Hudson River Sub-Bottom Profile Points

Hudson River Estuary Shallow Water Surveys. Subbottom Profile Points. Subbottom data was collected November 5 to December 15, 2009, in the estuary north from Saugerties to Troy.

Data Collection and Processing: Subbottom Data - Fugro utilized the EdgeTech SB216 Chirp subbottom profiler system for seismic data collection. This system was operated using a swept frequency range of 2-16 KHz, maximizing subsurface resolution within the very shallow near-surface material (1- 5 m beneath seafloor).

Subbottom data was processed and interpreted using Discover and SMT Kingdom software. The intent of the processing was to provide the NYSDEC with SEG-Y files that were properly filtered and spatially oriented to allow for near-surface interpretation of sediments in the Hudson River. Processing steps for the subbottom data included swell filtering to compensate for sea conditions during survey operations, compiling correct shotpoint navigation, and adjusting data gains for optimal interpretation. Subbottom data was used to assist in selecting sediment sampling locations.

Points were created every 300th trace (approximately 100 meters).

Original contact information:

Contact Name: John Ladd

Contact Org: Hudson River National Estuarine Research Reserve, NYS DEC

Phone: 845-889-4745

Email: jxLadd@gw.dec.state.ny.us

Our 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. 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.

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. -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. -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.

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. 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. 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.

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. 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.

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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. 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.

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. For the purposes of this project the low-tide line will be the line of zero depth relative to mean lower low water (MLLW) depicted on NOAA charts 12334, 12341, 12343, 12345, 12346, 12347 and 12348.

NOAA manages much of the data to users of digital geographic data.NOAA is in no way condoning or endorsing the application of this data for any given purpose.It is the sole responsibility of the user to determine whether or not the data is suitable for the intended purpose.It is also the obligation of the user to apply the data in an appropriate and conscientious manner.NOAA provides no warranty,nor accepts any liability occurring from any incomplete,incorrect, or misleading data, or from any incorrect,incomplete, or misleading use of the data.Much of the data is based on and maintained with ARC/GIS software developed by the Environmental Systems Research Institute (ESRI).In addition, much of the information presented uses conventions and terms popularized by ARC/GIS and its user community. NOAA in no way represents the interests of ESRI,nor acts as agents for them.

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Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.0.1770

Data are geo-referenced using differential GPS (DGPS) which results in a lateral accuracy of <+/-1 meter.

The data covers the area of the estuary north from Saugerties to Troy in areas of shallow water (defined as any part of the estuary covered by water at low tide and shallower than 5 meters relative to NAVD88. For the purposes of this project the low-tide line will be the line of zero depth relative to mean lower low water (MLLW) depicted on NOAA charts 12347 and 12348.

Position of the device was determined every second. After acquisition, navigation data was examined for outliers and applied to the subbottom profiler data to ensure proper positioning in the spatial domain.