Potomac River ADCP Bathymetric Survey, October 4-7, 2021

Bathymetric LiDAR technology was used to collect riverbed elevation data along the Potomac River. In support of this effort, a bathymetric survey with a boat-mounted acoustic Doppler current profiler (ADCP) was conducted in the study area during October 4-7, 2021. The study area consisted of four verification reaches on the Potomac River including: 1) Williamsport accessed through the Williamsport Park boat ramp below Conococheague Creek and RTE 11 (Williamsport), 2) Big Slackwater above C&O Canal Dam #4 accessed through the Big Slackwater Boat Ramp (Dam4), 3) Four Locks above C&O Canal Dam #5 accessed through the Four Locks Boat Ramp (Dam5), and 4) Little Tonoloway Recreation Area accessed through the Hancock Boat Ramp below RTE 522. Global Navigational Satellite Systems (GNSS) were used to concurrently collect survey grade real-time kinematic (RTK) horizontal and vertical coordinates of the ADCP transducer face. The riverbed elevations were collected using the ADCP with WinRiverII to export for post-processing in Microsoft Excel and RStudio. The GNSS equipment was programmed to continuously collect an observation every 1 to 2 seconds and the ADCP was programmed to continuously collect an observation every 1 second to 2 seconds. The corrected depths from the 4 ADCP beams were averaged and then subtracted from the GNSS derived elevation of the ADCP transducer face to compute the elevation of the riverbed. All spatial data is referenced horizontally to the North American Datum of 1983 (2011) and vertically to the North American Vertical Datum of 1988 (NAVD88). Grid coordinates are projected in Universal Transverse Mercator Zone 18 North and are represented in meter units. This data release consists of four (4) comma-delimited (*.csv) files with fifteen columns each: GNSS_ID, Time_hh_mm_ss, GNSS_Northing_M, GNSS_Easting_M, Computed_Elevation_M, GNSS_Transducer_Elevation_M, Computed_Mean_Depth_M, GNSS_PDOP, GNSS_Vertical Precision_M, GNSS_Satellites, ADCP_Ensemble_ID, ADCP_Temp_C, ADCP_Pitch_Degrees, ADCP_Roll_Degrees, and Type. This data release supersedes a previous version (https://doi.org/10.5066/P9EA0IKM) which contained a constant error of +0.344 meters in the GNSS antenna height reference elevations.