Bathymetry of Gargathy and Kegotank Bays, VA 2007-2009

This dataset contains bathymetry data for Gargathy and Kegotank Bays off the eastern coast of the Delmarva Peninsula. The dataset also includes information on the depth of many of the marsh and upland creeks leading into the bays. Elevations are in meters from mean-high water. Pixels are 10x10 meters on a side anD coordinates are UTM WGS84, Zone 18. Gomez 2008 (see network links) stated "The tidal range at Gargathy Neck was determined and used to obtain the relationship between NAVD88 and MHW. The tidal range was estimated by taking an average of 5 different stations close to Gargathy Neck. Tidal ranges at stations located in Gargathy inlet, Chincoteague, Metompkin, Wachapreague and Wallops Islands (www.co-ops.nos.noaa.gov/station-retrieve.shtml?type=bench+mark+data+sheets) were used to compute an average tidal range at Gargathy Neck. The tidal range at Gargathy Neck was determined to be 1.04 m + 0.18 m. Next, the relationship between NAVD88 and MHW was determined for Wallops Island and two stations at Chincoteague (www.co-ops.nos.noaa.gov/stationretrieve. shtml?type=bench+mark+data+sheets). About 40% of the tidal range was above NAVD88 datum and about 60% of the tidal range was below NAVD 88 datum. Based on these distributions around NAVD 88 datum, mean high water at Gargathy Neck, was determined 0.43 m above NAVD 88 and mean low water is 0.64 m below NAVD88 (Figure 9). The relationship between NAVD 88 datum and mean high water was used to adjust the bathymetric data to mean high water level." Here is the datum information from NOAA for one of the stations used. Station ID: 8630249 PUBLICATION DATE: 04/30/2003 Name: CHINCOTEAGUE, USCG STATION VIRGINIA NOAA Chart: 12211 Latitude: 37-deg 55.9' N USGS Quad: CHINCOTEAGUE WEST Longitude: 75-deg 23.0' W T I D A L D A T U M S Tidal datums at CHINCOTEAGUE, USCG STATION based on: LENGTH OF SERIES: 12 MONTHS TIME PERIOD: February 1977 - January 1978 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8638863 CHESAPEAKE BAY BRIDGE TUNNEL Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: HIGHEST OBSERVED WATER LEVEL (10/14/1977) = 1.136 MEAN HIGHER HIGH WATER (MHHW) = 0.561 MEAN HIGH WATER (MHW) = 0.511 NORTH AMERICAN VERTICAL DATUM-1988 (NAVD) = 0.322 MEAN TIDE LEVEL (MTL) = 0.270 MEAN SEA LEVEL (MSL) = 0.269 MEAN LOW WATER (MLW) = 0.028 MEAN LOWER LOW WATER (MLLW) = 0.000 LOWEST OBSERVED WATER LEVEL (01/11/1978) = -0.702