Description

Geodynamics conducted topographic, hydrographic and geophysical surveys in the marshes and backwaters behind Long Beach to support the design of a saltwater restoration project for the NY Governor’s Office of Storm Recovery.  The topographic surveys included terrestrial laser scanning  with a Riegl VZ-400ii, both static and mobile scanning from a vessel platform.  The laser scans supported delineation of vegetation zones, provided marsh elevation for marsh subsidence / accretion studies, calculated marsh pond elevations, and were integrated with geo-tagged digital imagery.  For the hydrographic survey component, multibeam (Kongsberg EM2040c) and singlebeam (Odom CV-100) surveys were conducted to render a complete Digital Elevation Model (DEM) of the 330² acre project area when combined with existing LiDAR data.  Geodynamics further collected simultaneous magnetometer data (using a Geomatics 882) in predetermined locations for identification of marine resources / objects and submerged items of potential cultural or archaeological interest.  Geodynamics also provided vessel support services for marsh vegetation and sediment sampling surveys.

The multibeam data was used to create a 1m resolution DEM containing elevations from –48.4ft to 0.6ft, providing an accurate representation of the seabed.  Multibeam acoustic backscatter data was used to create a ~1ft mosaic, which informed project biologists about differences in surface composition near the marsh edges; this data could also be used for bottom type classification or to guide future sediment sampling.   Final data deliverables included fully processed elevation surfaces in a file geodatabase with attached metadata in ESRI ArcMap v10.5 master MXD file to provide a fast, user-friendly, and comprehensive platform to assess survey results.