To support the modeling of the Colorado River water storage area capacity tables by the U.S. Geological Survey (USGS) Utah Water Science Center in the Glen Canyon National Recreation Area in Utah and Arizona, the USGS Earth Resources Observation and Science (EROS) Center has created an integrated 1-meter topobathymetric digital elevation model (TBDEM) for Lake Powell, the second largest man-made reservoir in the United States. Located in south-central Utah and north-central Arizona, Lake Powell is a reservoir on the Colorado River created by the flooding of a natural canyon by the construction of Glen Canyon Dam. The new Lake Powell TBDEM consists of the best available multi-source topographic and bathymetric elevation data for Lake Powell onshore and offshore areas. The Lake Powell TBDEM integrates three different data sources including topographic light detection and ranging (lidar) point cloud data, multibeam bathymetric surveys, and historic topographic surveys obtained from the Department of the Interior (DOI) Bureau of Reclamation (BOR) and USGS Woods Hole Coastal Marine Science Center. The topographic, bathymetric, and historic topographic surveys were sorted and prioritized based on survey date, accuracy, spatial distribution, and point density to develop a TBDEM model based on the best available elevation data. The Lake Powell TBDEM spatial resolution is 1-meter with the general location ranging from Glen Canyon Dam northwest of Page, Arizona to White Canyon, Utah with elevations from 948.28 meters to 1440.94 meters referenced to North American Vertical Datum of 1988 (NAVD88), National Geodetic Survey Geoid 12B. The topographic lidar survey was acquired from 4/2/18 to 4/3/18. The bathymetry survey was acquired from 10/8/17 to 11/15/17. The historic topographic surveys ranged from 1947-1959. Some of the nearshore void zone (not covered by lidar or multibeam) was filled with historic topographic surveys digitized from historical maps from 1947-1959 and a kriging interpolation as published by the USGS Coastal National Elevation Database (CoNED) Applications Project at https://doi.org/10.2112/SI76-008. Additional information regarding the CoNED Applications Project is located at https://www.usgs.gov/land-resources/eros/coned.

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.

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.

The dataset is a digital elevation model (DEM), in GeoTiff format, of the bathymetry of Dierks Lake, Howard and Sevier Counties, 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 “Dierks2018_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 bathymetric data collected in shallow and/or tree-ridden areas of the lake had been omitted, resulting in errors in the final products. The missing data were located and added to the geodatabase, the final products re-created, metadata edited accordingly, and the data release reviewed. In response to the second review, in select shallow and/or tree-ridden tributary arms of the lake where bathymetric data were sparse, points along the stream channels, digitized from historical topographic maps representing the pre-impoundment topography, were added to the dataset; select areas of erroneous bathymetric data were edited; and contours at the dam were adjusted based on the historical topographic maps. First release: March 2019; revised August 2019 (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/.

The dataset is a digital elevation model (DEM), in GeoTiff format, of the bathymetry of Dierks Lake, Howard and Sevier Counties, 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 “Dierks2018_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 bathymetric data collected in shallow and/or tree-ridden areas of the lake had been omitted, resulting in errors in the final products. The missing data were located and added to the geodatabase, the final products re-created, metadata edited accordingly, and the data release reviewed. In response to the second review, in select shallow and/or tree-ridden tributary arms of the lake where bathymetric data were sparse, points along the stream channels, digitized from historical topographic maps representing the pre-impoundment topography, were added to the dataset; select areas of erroneous bathymetric data were edited; and contours at the dam were adjusted based on the historical topographic maps. First release: March 2019; revised August 2019 (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/.

Bathymetric, topographic, and grain-size data were collected in April 2011 along a 27-mi (43.5 – km) reach of the Colorado River in Grand Canyon National Park, Arizona. The study reach begins at river mile 61.1, about 0.6 -mi (1 –km) above the confluence of the Colorado and Little Colorado Rivers and ends at river mile 88.1 at the upstream boundary of the Bright Angel Rapid (Phantom Ranch boat beach). Channel bathymetry was mapped using multibeam and singlebeam echosounders, subaerial topography was mapped using ground-based total-stations, and bed-sediment grain-size data were collected using an underwater digital microscope system. These data were combined to produce digital elevation models, spatially variable estimates of digital elevation model uncertainty, georeferenced grain-size data, and bed-sediment distribution maps. These data were created by the Southwest Biological Science Center, Grand Canyon Monitoring and Science Center as a component of a larger effort to monitor the status and trends of sand storage along the Colorado River in Grand Canyon National Park. This dataset is the hillshade generated from the 1-meter resolution digital elevation model (DEM_EGC_Apr2011.tif) associated with this data release.

Bathymetric, topographic, and grain-size data were collected in April 2011 along a 27-mi (43.5 – km) reach of the Colorado River in Grand Canyon National Park, Arizona. The study reach begins at river mile 61.1, about 0.6 -mi (1 –km) above the confluence of the Colorado and Little Colorado Rivers and ends at river mile 88.1 at the upstream boundary of the Bright Angel Rapid (Phantom Ranch boat beach). Channel bathymetry was mapped using multibeam and singlebeam echosounders, subaerial topography was mapped using ground-based total-stations, and bed-sediment grain-size data were collected using an underwater digital microscope system. These data were combined to produce digital elevation models, spatially variable estimates of digital elevation model uncertainty, georeferenced grain-size data, and bed-sediment distribution maps. These data were created by the Southwest Biological Science Center, Grand Canyon Monitoring and Science Center as a component of a larger effort to monitor the status and trends of sand storage along the Colorado River in Grand Canyon National Park. This dataset is the hillshade generated from the 1-meter resolution digital elevation model (DEM_EGC_Apr2011.tif) associated with this data release.

Bathymetric, topographic, and grain-size data were collected in April 2011 along a 27-mi (43.5 – km) reach of the Colorado River in Grand Canyon National Park, Arizona. The study reach begins at river mile 61.1, about 0.6 -mi (1 –km) above the confluence of the Colorado and Little Colorado Rivers and ends at river mile 88.1 at the upstream boundary of the Bright Angel Rapid (Phantom Ranch boat beach). Channel bathymetry was mapped using multibeam and singlebeam echosounders, subaerial topography was mapped using ground-based total-stations, and bed-sediment grain-size data were collected using an underwater digital microscope system. These data were combined to produce digital elevation models, spatially variable estimates of digital elevation model uncertainty, georeferenced grain-size data, and bed-sediment distribution maps. These data were collected by the Southwest Biological Science Center, Grand Canyon Monitoring and Science Center as a component of a larger effort to monitor the status and trends of sand storage along the Colorado River in Grand Canyon National Park. This dataset is a 1-meter resolution digital elevation model.

Bathymetric, topographic, and grain-size data were collected in April 2011 along a 27-mi (43.5 – km) reach of the Colorado River in Grand Canyon National Park, Arizona. The study reach begins at river mile 61.1, about 0.6 -mi (1 –km) above the confluence of the Colorado and Little Colorado Rivers and ends at river mile 88.1 at the upstream boundary of the Bright Angel Rapid (Phantom Ranch boat beach). Channel bathymetry was mapped using multibeam and singlebeam echosounders, subaerial topography was mapped using ground-based total-stations, and bed-sediment grain-size data were collected using an underwater digital microscope system. These data were combined to produce digital elevation models, spatially variable estimates of digital elevation model uncertainty, georeferenced grain-size data, and bed-sediment distribution maps. These data were collected by the Southwest Biological Science Center, Grand Canyon Monitoring and Science Center as a component of a larger effort to monitor the status and trends of sand storage along the Colorado River in Grand Canyon National Park. This dataset is a 1-meter resolution digital elevation model.