Bathymetric Survey of the Ichilo and Sajta Rivers, near Puerto Villarroel, Bolivia, May 23-24, 2019

A bathymetric survey was conducted upstream and downstream of the confluence of the Ichilo and Sajta Rivers near Puerto Villarroel, Bolivia. The surveyed reach extends approximately 12 kilometers upstream of the confluence along the Ichilo River, approximately 2 kilometers upstream of the confluence along the Sajta River, and 1.5 kilometers downstream of the confluence. The bathymetric data include survey point data provided as a text file of horizontal coordinates in Universal Transverse Mercator Zone 20 South, in meters. The river bed elevation is expressed as height above the WGS-84 ellipsoid, in meters. USGS personnel collected bathymetric data from May 23, 2019, through May 24, 2019 using an interferometric multibeam echosounder and an inertial navigation system (INS). The INS measured the attitude (pitch, roll, and yaw) and determined the position of the echosounder during the survey using a differential Global Navigation Satellite System. The INS files were also stored during the survey and later post-processed to determine a more precise (centimeter-level) position of the echosounder.