Site description and associated GPS data collected at eleven study sites within the Grand Bay National Estuarine Research Reserve in Mississippi

On 20210525 and 20210526, researchers at the GBNERR collected Real-time Kinematic (RTK) GPS data and site descriptions at eleven locations in GBNERR. Data were collected in the Mississippi State plane coordinate system and elevations in North American Vertical Datum of 1988 (NAVD88). Coordinates were converted to the North American Datum of 1983-Universal Transverse Mercator Zone 16N (NAD83 UTM 16N) using the ArcGIS "Reproject" tool. GPS data were collected using a Trimble R10 Model 3 Global Navigation Satellite System (GNSS) and TSC3 data collector. Each were attached onto a 2-meter (m) graphite rod with a mounted foot to obtain both horizontal and vertical shoreline position. The horizontal error of the Trimble R10 GPS points was ± 8 millimeter (mm) + 0.5 part per million (ppm) root mean square (RMS) and vertical error was ± 15 mm + 0.5 ppm RMS. GPS data represent transects at the eleven study sites that extend from the near shore estuary into the marsh. At each site, at-least three plots were chosen to collect site description data. Each transect consists of two points on the marsh platform, one at the top of the scarp (or estimated top if no scarp was present), bottom of the scarp (or estimated bottom if no scarp was present) and one point in the nearshore estuary. Site data collection included 1) dominant vegetation species and approximate coverage. The most dominant vegetation species and percent coverage at each plot at the shoreline were estimated by using a 1 meter x 1 meter quadrat; 2) presence or absence of an erosional scarp; 3) vegetation notes about the marsh of the nearshore estuary; 4) tidal wrack presence and distance from the shoreline; 5) general sediment type at the shoreline determined by visual observations.