Sometimes during a demonstration you are struck by surprise. This was one of the worst.

The Norrea is a small stream in Denmark which has a lot of vegetation on the bed and on the shore, Fig 1. If the guys are gutting grass upstream during the demo you will catch a lot of dirt but you won't measure any discharge. General opinion was that these circumstances do not allow any discharge measurements at all. Propellor type of instruments would not turn or get far too heavy. Bottom tracking ADCPs won’t work due to the thick and moving vegetation on the bed, let alone the floating stuff. I was told to go home ( 803 km) and return some other time. Which I did not.

I said, let's give it a try from the bridge. If the Qliner gets too dirty I'll give it a wash and try again. And so I did, washing the thing by bumping it on the water a couple of times. We obtained good results


Fig 2: Qliner during the measurements just after cleaning.

Expected discharge, extrapolation from the day before without reference, was 3 m³/s. We got 2.9 m³/s, Fig 3. I was happy and ready for a long drive home. The Danes were surprised !



Fig 3: Results of the third Qliner measurement in Qliner Review. The graph on the lower left side shows the depth profile in segments. Going upward on the left the discharge, specific discharge and flow velocity are shown. Lower right corner shows general result. The graph on the right shows a velocity profile with in red measured values and in blue an exponential profile. Upper right part shows results of the 7^th