RiverPro velocity underestimation

Hi Alex – haven’t seen this here but will look further?

Here’s an example attached.

Regards – Evan.

I checked 10 or so RiverPro measurements and found 1 that showed this behaviour. It was even labeled bin_3.

I am guessing that it may take a specific combination of water temperature and backscatter to cause this issue.

Dave

Hi, Alex.

I have not seen this in a discharge measurement, but I have seen a similar feature in a test with a RiverPro anchored in a lake. I really hope I would have noticed it in my own discharge measurements, and I have had a new look at some of them now without seeing the feature. The anchored riverpro shows a HIGHER velocity magnitude (and east and north velocity) in the first bin below the surface bins in WinRiver when I average a lot of ensembles. See attached screenshot. (The reason it was anchored is that we used the data to check if a still lake was actually still when testing fro flow disturbance). If not averaging, we only see low velocity magnitudes in the top bins and higher velocity magnitudes in the rest of the bins, since they are more noisy.

Hi Alex and all.

I have seen something similar on a StreamPro measurement as well. Overestimation of speed in the 5th bin. Depth around 1-1.3 meters, down to 2 meters. ARC boat. Clear water in the outlet of a lake. I don’t know what this is. If it was some double reflection phenomena the erroneous velocity should have followed the shape of the river bed.

I have used this instrument many times and this is the only time I have seen this happen.

Any ideas?

Kristofffer

PS: I know it was too shallow for the ARC boat to be ideal here. DS

Hi Alex

I also checked several RiverPro measurements and none of them showed this behaviour. However, I forwarded yout question to the operations technicians to get a wider spectrum of responses.

Best
Ole