NCCOS Assessment: Orthoimagery and sediment core description data in Galveston Bay, Texas from 20231010 to 20231011 (NCEI Accession 0303740)

This dataset contains imagery, GPS coordinates, elevation data, and sediment characteristics collected from three historical marsh mound restoration projects in Galveston Bay, Texas. These three marsh restoration sites—Jumbile Phase II, J Cove, and Mcallis Point—were revisited to evaluate their long-term performance. The data collected for assessment is stored in four .tif files and two .csv files. The .tif files consist of ortho mosaic images of each site, captured using a DJI Phantom 4 Pro drone. The .csv files contain detailed gps data and sediment core information, including bulk density, grain size, and percent carbon. The Trimble R12 GNSS System was utilized to capture the GPS data for sediment cores, ground control points (used for georeferencing drone imagery), and the topography of marsh mounds. A total of twenty sediment cores were extracted by driving a 7 cm diameter polycarbonate tube into the ground. The cores were sectioned in the field for transport. Sediment cores were further analyzed at the lab to determine sediment characteristics. Bulk density and grain size were determined for every 5 cm interval of the core by measuring the total weight of the wet core then splitting the interval into two equal-weight halves. One half was used for bulk density, while the other was used for grain size. The bulk density half was dried, weighed, and subsampled to measure percent carbon with a Perkin Elmer 2400 series II CHNS/O elemental analyzer. The grain size half was sieved into 4 categories: gravel, macro organic matter (both >0.2mm), sand (0.063-2mm), and silt (<0.063mm). For the top 5 cm of the cores, the remaining half of the bulk density sample was re-weighed after drying and subsampling, then ashed in a muffle furnace to calculate loss on ignition (LOI). More information on these sites can be found here: https://arcg.is/1urP5j