OVERVIEW
Bathymetric and topographic survey data collected during the TURTLE experiments on Galveston Island, TX, USA in the fall of 2023. The data includes handheld RTK-GPS cross-shore profiles, collected between October and December 2023, and bathymetric echo sounder survey data, collected on 29 January 2024. This dataset is part of the collection "TURTLE: Measurements of groundwater, hydrodynamics, sand temperature, and sediment characteristics at two beach transects on Galveston Island, Texas, USA".

CONTENTS
- GPS
    Directory with CSV files of the RTK-GPS cross-shore profiles of the entire field campaign, divided in one folder for each deployment (D1, D2, D3). Also contains profile plots as PNG images.
- Echo
    Directory with CSV files of the bathymetric echo sounder survey (one file per location, TT and SW)

DATA FORMAT
CSV and PNG files

DATA STRUCTURE
The GPS profile files are named as YYYYMMDD_AA_BB.csv, where YYYYMMDD represents the date the transect was recorded, AA the deployment (D1/D2/D3) and BB the field site (TT/SW). Each CSV file contains the following variables:
    'time'  Timestamp of the record in unix time (seconds after 1 January 1970, 00:00, UTC)
    'e'     Easting coordinate in meters relative to NAD83 Texas South Central (EPSG:6587)
    'n'     Northing coordinate in meters relative to NAD83 Texas South Central (EPSG:6587)
    'z'     Elevation coordinate in meters relative to NAVD88
    'lat'   Latitude in degrees (EPSG:4326, converted from Easting/Northing)
    'lon'   Longitude in degrees (EPSG:4326, converted from Easting/Northing)
    'x'     Cross-shore distance in meters in the local coordinate system
    'y'     Alongshore distance in meters from the transect axis to which the point is projected

The bathymetric echo sounder CSV files are named as 20240129_BB.csv and have the same variables as above, except x and y as they were not converted to the local coordinate systems. Furthermore, they have an additional variable 'line' which represents the transect line, ranging from 1 to 9 with line 5 being the longer transect at each location (see details in Christiaanse et al. 2024).

USAGE
Any software or programming language that can read *.csv files can be used to analyse the data (Python, R, C++, ...). We used Python for all processing and operations on the data. Using the pandas library in python the files can be read through the command pandas.read_csv().

REFERENCE
Christiaanse, J. C., Antolínez, J. A. A., van der Grinten, M. J., Taal, F., Figlus, J., Dellapenna, T. M., Ritt, B., Marshall, C. D., Tereszkiewicz, P. A., Cohn, N., Majzlik, E. J., & Reniers, A. J. H. M. (in review). Measurements of groundwater, hydrodynamics, and sand characteristics at a dissipative sea turtle nesting beach. Scientific Data.