Qliner

A party with the Qliner in the Alps
Sicco Kamminga and Babak Farshchi
October 2003

With great support of Werner Ertl (Austria), Martin Kaspar (Switzerland), Claudio Franzoni (Italy) and Ketil Horn (from Norway)

The Qliner has become quite used to the low flows in the Dutch water in the very very dry summer of 2003. How will it behave in the Alps ?

Let's go and start in the Aare in Bern. The Aare makes some nice turns through the beautiful city of Bern. The river has carved its way through the rock of the city which is now quite far above it. We immediately admit, the Aare is quite different from what we are used to. It is some 50 m wide and the flow is a lot. A little scary we decide to have lunch first with our Swiss companions. Very friendly guys, we came to talk with the head of department so we were nicely dressed. Instead of that we go for field work in the rain.

No delay anymore. The side has a nice cabin, good for the suite, and a cable way. So we connect the Qliner to the cable way and put it in the water. I explain the settings and tell them that we expect an accuracy of just below 1%. Our friends do not believe that of course. We start anyway with all the courage we have. We are happy that our Qliner boat is designed for Norwegian rivers. It is really very stable in the flow. Our friends already get a bit convinced. We get a already promising 99.9 m3/s. We repeat the action. Now we obtain 101.6. The discharge obtained from a water level sensor here is 103. Our friends are impressed

Through the Alps to Austria we go. The river Drau is a nice one and luckily not so very different from the Aare. This time we want to out beat our Austrian guests and we visit the site the day before the measurements. We make a quick and sunny measurement from the bridge next to the cable way. The bridge has a lot of large piles so we measure alone in between the piles and we see a nice 97 m3/s. Later on I correct the vertical profiles for a higher bottom friction so we get 93 m3/s.

Next day we have an early start, less sun and many, many Austrian friends eager to see our toy. They see our rope and laugh, a high-tech thing with rope? Yeah yeah, we say lets take 10 measurement positions. You need 25 at least Ok, its their water so we go all across the river in 25 small steps. They tell us that based on the current water level the discharge is 86 sharp. We told them what we did the other day and that we saw 93. Oh, no comment yet. At two third we just have 30 so we get a little nervous, But the flow is strong on the other side and their we go, a fine 86.6 ! They are quite surprised and only then they say that according to their water level yesterdays 93 is 93.8. Good start for us. We get very brave now. Let us make another one but now on just 13 positions. Very brave and lazy because our friends will do the work this time. The water level sensor tells us that the discharge has increased to 90. They do very well in less time. The answer is .... 90,3 ! They are convinced, this is it.

Werner wants to keep the instruments and make additional demo' s all over Austria the week after. We instruct him over lunch. We tell him that he should measure the distances of the measurement positions accurately. That is the main trick in discharge measurements. The Qliner will do the rest of the work. Then, he should do a measurement always twice! It is much more fun to see nearly the same number popping up once more.

Werner also gets a chance to use the EasyQ. It is really meant for long time deployments. But ok, a demo takes just an hour. It is a fun demo. Werner makes a Qliner measurement in a nice river. The discharge is 105 m3/s. Then he deploys the EasyQ. It measures in three cells but it could have just been one. The river is nearly 60 m wide so our three cells are all close to the side. Never mind, we use a quite standard hydraulic formula to compute discharge from the EasyQ data and the depth data obtained from the Qliner, see the Figure below. And what do we get: 107.2 m3/s ! The turbulence in the river helps us a lot.

EasyQ data combined with Qliner depth readings to obtain total discharge. From the EasyQ velocity in three cells we compute depth averaged velocity, (colors according to colorbar) all the way to the other site taking depth into account.

What a pity for Werner. He would have liked it to play forever with the Qliner. To Italy it must go. This time Ketil and Claudio will do the job. Well job, multiple jobs because there are more rivers than just one ready for a demo.>

In a smaller river we have the opportunity to make a comparison with a propeller measurement. Both systems are mounted on the cable way. We obtain 2.82 m3/s with the Qliner on 10 measurement positions. The propeller is used on just 4 positions and gives 2.50 m3/s. This difference is too large! We analyse our data and conclude that if we had used the Qliner at exactly the same spots as the propeller we would have been close to 2.6 m3/s. The local guys are anyway impressed with the easiness of the work and the good results.  
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