The Riverflow 2016 conference had a full session on recent research in image-based measurements and video analysis. It is exciting to watch innovation in process as these researchers learn to exploit the capabilities of emerging consumer technologies. Never mind that the primary use of these technologies is so that people can instantly share their sense of place in the ‘real world’ within the virtual world where they really spend their lives. Without the billions of people motivated to lay claim to their physical existence with photos and videos, the technology for water monitoring using digital imaging would neither be accessible nor affordable.
A different point of view changes nothing but it can change everything. Last week I wrote about how unmanned Aerial Vehicles (UAV), also known as drones, could be used for Large Scale Particle image Velocimetry (LSPIV) to get surface velocity measurements, which when combined with surveyed cross-sections can produce extreme flow gaugings. That same drone, equipped with the same camera, can also provide the cross-sectional information needed to complete the job.
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.