Velocity measurements around the sill bubble curtain in Peoria Lock on the Illinois River, Illinois, September 17-18, 2019

Bubble curtain systems, also called "bubblers," are used in navigation locks to prevent the buildup of ice around the gates in the winter. It has been proposed that bubblers could potentially serve an additional purpose as a deterrent to the upstream movement of aquatic invasive species through locks. An interagency study involving the U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, and the U.S. Geological Survey is aimed at assessing this potential (Asian Carp Regional Coordinating Committee, 2019). As part of this effort, on September 17 and 18, 2019, the U.S. Geological Survey measured water velocities around the bubble curtain system in Peoria Lock on the Illinois River. Peoria Lock has "sill bubblers" that extend across the lock chamber where the upstream and downstream gates are located when closed, and "recessed bubblers" within the recessed areas along the lock wall, where the gates are located when open. The sill bubblers and the recessed bubblers in Peoria Lock all run from the same air compressor. The goal of the study was to characterize the velocities generated by the downstream sill bubbler while the upstream gates of Peoria Lock were closed and the downstream gates were open, as they would be while a vessel approached and entered the lock to move upstream. The upstream sill bubbler and the recessed bubblers were disconnected from the air compressor during the measurements to ensure maximum air pressure through the downstream sill bubbler. During data collection, about half of the downstream sill bubbler was partially buried with sediment, such that the bubble curtain extended only partway across the width of the lock (see thumbnail image). Additionally, velocity measurements were made during open river conditions, in which the wickets of Peoria Dam were lowered to allow water to flow freely. Commercial and recreational vessel traffic can bypass Peoria lock by transiting over the lowered wickets during open river conditions and therefore did not interfere with the velocity measurements. Velocity measurements were made using a Teledyne RDI Rio Grande 600 kHz acoustic Doppler current profiler integrated with a Hemisphere V102TM differential global positioning system (GPS) receiver deployed from a manned boat. Measurements were made along six cross-sections at a 17-meter spacing (three upstream and three downstream from the downstream sill bubbler; X1-X6) and along three longitudinal lines that cross the downstream sill bubbler (L1-L3). Six transects were measured along each line. Each transect was initially processed in Teledyne RDI's WinRiverII software version 2.18, then the transects on each line were averaged using the Velocity Mapping Toolbox (VMT) version 4.09 using a 0.25 meter horizontal spacing and a 0.5 meter vertical spacing (Parsons and others, 2013). Additional stationary measurements were made at 15 points where the measurement lines intersect for five minutes each. The stationary measurements were processed in WinRiverII and in VMT to project the data onto a single position, then time-averaged to produce vertical velocity profiles with a 0.5 meter vertical spacing. The cross-section and longitudinal line data, as averaged in VMT, are given in a comma separated values (CSV) file in which each measurement bin (easting, northing, and depth from surface) is associated with a velocity measurement decomposed into east, north, and vertical components (positive east, north, and up), a velocity magnitude, and a velocity direction. The velocities are also decomposed into the streamwise and transverse components according to the orientation of the measurement line. Similarly, the time-averaged vertical velocity profiles from the stationary measurement data are given in a CSV file. References Cited: Asian Carp Regional Coordinating Committee, 2019, 2019 Asian Carp Action Plan, accessed January 14, 2020 at http://asiancarp.us/Documents/2019-Action-Plan-Amended.pdf Parsons, D.R., Jackson, P.R., Czuba, J.A., Oberg, K.A., Mueller, D.S., Rhoads, B., Best, J.L., Johnson, K.K., Engel, F., and Riley, J., 2013, Velocity Mapping Toolbox (VMT): a processing and visualization suite for moving-vessel ADCP measurements, Earth Surface Processes and Landforms, https://doi.org/10.1002/esp.3367.