The New Zealand Hydrological Society hosted an ADCP flow regatta as part of the Technical Workshop in Dunedin from April 3-6. The field event followed a full day training session presented by Kevin Oberg from the USGS on the use of the QRev program. QRev is the new Acoustic Doppler Current Profiler (ADCP) discharge measurement processing software developed by the USGS Office of Surface Water for standardizing discharge computations and automating the review and quality assurance of ADCP discharge measurements.
Extreme flows are extremely hard to gauge, hence we get very few gaugings to accurately define the top-end of stage-discharge rating curves. This is a problem. Whereas empirically calibrated functional relationships can be trustworthy for the purpose of interpolation, they can be notoriously unreliable for extrapolation. One needs to be very careful about extrapolating any rating curve to an ungauged extreme.