Sontek Rivercat and Toughbook
I thought I might also outline a couple subtleties about the system so when you're tweaking the configuration you get the best performance. First, the unit has limited processing power and so you're limited both in the number of 'cells' you can measure in the vertical water column and also how thin these slices can be. I think I normally start with high cell numbers and thin slices and then adjust them downwards until the computer program stops being crotchety. You can also run across the river once just to see how deep the river cat says it is (if it's to deep to eyeball) and then readjust your cell count and thickness configuration.
One prep thing to do before starting recording the flow is to calibrate the compass. If say you're gaging the Put and only the Put for like 8 days in a row then you don't need to recalibrate after your first visit but if you were hopping back and forth between two rivers then it would be better to recalibrate the compass each time. Calibrating is pretty easy and I'll show you how but you also need to know the declination. If you have a GPS you can find the declination (instructions for Garmins here) by going into the navigation set up and changing the navigation from true north to magnetic north. Then you should see a new box that appears that tells you what the declination is for the spot you're in.
So, here's the sequence for getting it all up and running: 1) put the unit together by first attaching the frame to the brains box. Next attach the floats. Finally attach the data cable & radio antenna.
2) Tie the rope to the mounting bracket on the front of the rivercat. Be sure to use good knots like a bowline here since we don't want this puppy floating away on us.
3) Fire up the computer, connect the radio to the serial port on the computer, and start the RiverSurveyor program that Sontek includes for the PC. There's a bit of art involved in this step. The radio seems to have a directional antenna or maybe just not really much of an antenna so line of site is everything. However, the cables are short and the radio runs off like 9V DC so we need an inverter and AC adapter so, you'll end up with a string of cables coming out the window of the excursion to the radio perched on the roof or something like that.
4) Before taking the river cat down to the river you'll want to double-check your radio link at the truck (so if it doesn't work when the river cat's down on the river you'll have known you had a good connection before you separated it from the computer). You can do this by using the river surveyor software to connect to the river cat.
5) Time to calibrate the compass. This is easier if you have the declination handy like I mentioned earlier. If you don't have a GPS though you can pretty easily dig up declination off some USGS or NOAA websites if you do a quick search for magnetic declination / variation. Calibrating is simple. Follow the directions in the program but basically, walk slowly around in a circle twice and rock the rivercat back and forth and flop it around. In addition to the compass calibration the pitch sensor gets calibrated during this procedure.
6) Okay, now you can go down to the river and get going. While one person very slowly walks across the bridge across the river the second person pushes buttons on the computer. There's actually not much to push. There's a record button and you'll push that when you're ready to begin recording flow and then a second time once the rivercat gets across the river. Then I keep an eye on the water speeds, flow calculations, and the diagnostic data that I'll go over with you this afternoon. Diagnostic data is important because that can help in determining the quality of the flow calculations. I like to keep an eye on beam strength and something else that's set up on the computer but I can't remember off the top of my head. I mainly observe the numbers. Absolutely they don't mean much to me (it's like decibels or something) but I'll try to help you be able to differentiate between decent data and suspect data and then for the suspect data help to perhaps narrow down what the problem is and if it's a deal killer for the data collection.
7) Another general note is how many times to go across the river. Since the method is so straight forward I actually go across quite a few times if I have time, like up to 10 (extreme case) but that's mainly to get a feel for how the doppler's reacting to the river on this particular day. If you have the time available and can run back and forth across the river a few times it's a great way to get going on the learning curve because you'll see how the rivercat responds to eddy's, high water, sediment transport, and turbulence (a key factor). You also may discover that one direction (left to right or right to left) gets more consistent flow measurements. That's all stuff to be aware of but I try to at minimum go across four times if I can spare the time. Site selection is also important. Your sites are pretty much picked out but if you do this someplace else the number one thing to watch for are eddys. Shoot for a cross-section of the river where there isn't much turbulence or eddys because that's where you'll get most variability in your data. The backwater spins the rivercat around and shoots the doppler in odd directio
