Channel thalweg elevations for a 5 mile reach on the Maumelle River upstream of Lake Maumelle, Little Rock, Arkansas

The U.S. Geological Survey (USGS) in cooperation with the U.S. Army Corps of Engineers (USACE) did a bathymetric survey of the lower reach of the Maumelle River upstream of Lake Maumelle, near Little Rock, Arkansas, from July 9-11, 2019. Channel bed elevations (thalweg) were collected to support a USACE modeling effort on a 5-mile reach of the Maumelle River. In parts of the reach where the water was partially impounded, depth data were collected using an acoustic Doppler current profiler (ADCP) coupled with a survey-grade deferentially corrected global positioning system (GPS) receiver. Depth data were converted to channel bed elevation data by subtracting the depth value from the GPS derived water-surface elevation. Additional channel bed elevations (topographic data) were surveyed directly using survey-grade GPS along the channel where the water depth was too shallow to be measured with the ADCP. These topographic measurements were concentrated in areas where the slope of the river channel had larger changes, and between these measured points, the data were linearly interpolated and densified to approximately a 3-foot horizontal spacing.

Positional location of the surveyed points was referenced to the North American Datum of 1983, and channel bed elevation, reported in feet, was referenced to the North American Vertical Datum of 1988. Surveying was done according to the standards described in Rydlund and Densmore, 2012.

The data are provided in the Environmental Systems Research Institute (ESRI) shapefile format consisting of a group of files that have been compressed into a zip archive that is named maumelle_thalweg_2019.zip.

References

Rydlund, P.H., Jr., and Densmore, B.K., 2012, Methods of practice and guidelines for using survey-grade global navigation satellite systems (GNSS) to establish vertical datum in the United States Geological Survey: U.S. Geological Survey Techniques and Methods, book 11, chap. D1, 102 p. with appendixes.