Digital elevation model of the bathymetry of Gillham Lake, Arkansas

The dataset is a digital elevation model (DEM), in GeoTiff format, of the bathymetry of Gillham Lake, Sevier County, Arkansas. The extent of the DEM represents the area encompassing the extent of the aerial Light Detection And Ranging (LiDAR) data used in the project. Horizontal and vertical units are expressed in meters. The DEM was derived from an LAS dataset (an industry-standard binary format for storing aerial LiDAR data) created from point datasets stored in “Gillham2018_gdb”. The point datasets include aerial LiDAR data from a survey conducted in 2016 by the National Resources Conservation Service (U.S. Geological Survey, 2017), point data from digitized historical topographic maps, and bathymetric data from a survey conducted in June 2018 by the Lower Mississippi-Gulf Water Science Center of the U.S. Geological Survey (USGS) using methodologies for single and multi-beam sonar surveys similar to those described by Wilson and Richards (2006) and Richards and Huizinga (2018). In April 2019, it was discovered that some of the areas in shallow and/or tree-ridden areas of the lake that had not been surveyed needed additional data in order to generate a more topographically realistic surface. Additional data were interpolated from a combination of elevation data from pre-impoundment topographic maps and from the point datasets of the bathymetric and LiDAR surveys provided in Esri file geodatabase. The interpolated data was added to the geodatabase, the final products re-created, metadata edited accordingly, and the data release reviewed. In response to the second review, a vertical datum discrepancy between the single beam and multi-beam bathymetric datasets was addressed and select areas of erroneous bathymetric data were edited. First release: October 2018; revised April 2020 (version 1.1). The previous version can be obtained by contacting the USGS Lower Mississippi-Gulf Water Science Center using the "Point of Contact" link on the landing page on ScienceBase. References: Richards, J.M. and Huizinga, R.J., 2018, Bathymetric contour map, surface area and capacity table, and bathymetric difference map for Clearwater Lake near Piedmont, Missouri, 2017: U.S. Geological Survey Scientific Investigations Map 3409: 1 sheet, https://doi.org/10.3133/sim3409; U.S. Geological Survey, 2017, Lidar Point Cloud - USGS National Map 3DEP Downloadable Data Collection: U.S. Geological Survey, https://nationalmap.gov/3DEP; Wilson, G.L., and Richards, J.M., 2006, Procedural Documentation and Accuracy Assessment of Bathymetric Maps and Area/Capacity Tables for Small Reservoirs: U.S. Geological Survey Scientific Investigations Report 2006-5208, https://pubs.usgs.gov/sir/2006/5208/.