Channel Mapping of the Colorado River in Grand Canyon National Park, Arizona - April 2014, river miles 61 to 88 — Data

Bathymetric, topographic, and grain-size data were collected in May 2014 along a 27 mile (43.5 kilometer) reach of the Colorado River in Grand Canyon National Park, Arizona. The study reach begins at river mile 61.1, about 0.6 miles (1 kilometer) 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). We refer to this reach as Eastern Grand Canyon (EGC) and all products include the EGC abbreviation in the filename. 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 a digital elevation model (DEM) and bed-sediment distribution map. This data release contains four items: 1) a DEM of the study reach; 2) a hillshade model of the DEM; 3) a bed sediment distribution map of the study reach; and 4) a shapefile of fiducial polygons used to assess DEM uncertainty. 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.