Importing Bathymetric Datasets

Multiple Bathymetric Datasets

Limited bay bathymetry

NOAA – Offshore datasets

LIDAR – Shoreline and nearshore (important for structure resolution)

Channel

NJ State maintains north channel and north bay channel

Federally maintained entrance and south channel (15 years)

NAN-supported field data collection

Included bathymetry of the backbay (Spring High Tide)

Common Spatial Reference Datum & Vertical Datum

Tides and Currents (NOAA)

http://tidesandcurrents.noaa.gov/station_retrieve.shtml?type=Datums

Vertical Datum Conversions

Prep for the Coastal Modeling System

Based off of a Cartesian grid
Planar coordinate system
Model computation is in metric and depths are positive from zero (elevations are flipped)
Grid is generated based off of a single bathymetry file stored in SMS scatterset file format
Vertical datum is not specified and is assumed local
The boundary condition forcing (tidal) must be in the same datum as the bathymetry
Typically modeling grids are brought to a mean datum such as mean sea level (msl) or mean tide level (mtl)
This requires that all datasets are brought in to unified projection, datum, and units
Shark River Inlet bathymetry will be converted to State Plane horizontal coordinates in meters with the vertical datum set to MSL in meters

Reprojecting Coordinates and Changing Datums

Object Projection tells SMS what the coordinates are to be project in. This can modify the location that SMS will display the dataset. Checking “Specify” Project Projection is how coordinates are converted to a different projection and vertical datum.

Converting Elevations to Depths (CMS Requirement)