Velocity Indexing Discharge Measurements with Argonaut-SL

The USGS California District uses four SonTek/YSI Argonaut-SL (side-looking) systems to obtain index velocities at four locations in the California Delta. Two of the SLs are mounted on the back side of wooden bridge fenders looking out from under the fender towards center channel (Figure 1).

The third SL is mounted on a farmer's pump stand. The fourth SL replaced a UVM that was knocked out by a barge, and is mounted at the end of a gauging station catwalk. Figure 2 shows a comparison between the SL and a UVM.

The SLs are connected to Campbell Scientific data loggers via the "Sidekick" SDI-12 interface. After five months of use, the USGS reports that they have not had a single "glitch" with any of the SLs.

*Photograph and chart courtesy of the USGS.

• Argonaut-SL