Modified topobathymetric elevation data for Lake Powell

This dataset provides a modified version of the previously published Lake Powell topobathymetric digital elevation model (TBDEM; Poppenga and others, 2020). The original TBDEM is comprised of four source datasets: (1) a 2017 1-meter multibeam bathymetric survey; (2) a 2018 topographic light detection and ranging (lidar) derived digital elevation model (DEM); (3) a historical topographic DEM that was interpolated from contours maps created in 1947 and 1959; and (4) interpolated topography where gaps existed in the bathymetric and lidar data or where historical data were not suitable (Poppenga and others, 2020). For this data release, two corrections were made to the TBDEM to address errors associated with the historic DEM and interpolated topography across data gaps: (1) filled in selected gaps of the TBDEM dataset that were corrected with the historic DEM but have since been filled with sediment; and (2) spliced alternate topographic data sources instead of the hydro-flattened elevations in the river channel upstream of the Colorado and San Juan River deltas. The modified TBDEM was generated in a horizontal projection of UTM Zone 12N, North American Datum of 1983, referenced to the North American Vertical Datum 1988 (NAVD88), Geoid 12b at a 1-meter horizontal resolution. The modified TBDEM and an updated spatial metadata shapefile detailing data sources used and modifications made to the TBDEM are included with this release.