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Chip 08-09-2010 01:21 AM

GIS channel mapping on the Snake
Just spent a week rowing for science, with my Jack's Flyer Cat rigged as a mobile instrument platform.

The staff in front has an echo sounder at the base, for measuring depth, with a data logger in the yellow pouch and a GPS rover at the top. We set up a GPS base station on a hill overlooking the upper Snake River that allowed us to map the channel and features in RTK (real-time kinetic) mode, with great accuracy.

We were towing a Doppler current profiler on its own little trimaran (note the custom lodgepole spar, which I found on the shore of Jackson Lake). We also had a second GPS rover and three handheld controllers to operate the devices and log data, so we could both survey at the same time.

We did continuous channel profiles from Pacific Creek to Moose and two days of insanely detailed mapping of a full meander and two large point bars.

I started with this sort of work in the days of optical levels, chains, and stadia rods. Given that gear, it would have taken a crew of three or four a couple strenuous weeks to log the same amount of survey data. The continuous channel profiles wouldn't have been possible, nor would the cross-sections we logged in places where the river was too deep and the current too strong for wading.

I'd grab roots or stick oars in the bed to hold us while Carl keyed up the equipment. Then I'd row like a bloody Viking to keep a straight course to the other bank, which was mostly possible.

There were some wild thunderstorms. This is how it looked just before we got big thunder, crazy lightning, and wind-driven rain.

There's so much boat traffic on the upper Snake that large mammals avoid the river in daylight (except for bison). But at night and in the early hours, the critters are active. Here are the tracks of a big beaver (I think), an elk calf, and a wolf, with a size 13 Chaco-print for scale.

Given the setup and troubleshooting time for the GIS stuff, we'd leave the research station at 8:30, set up, do the shuttle, get on the river about 11 am, and pull off around 8 pm. (That's the longest time I've rowed a boat without a beer in ten or fifteen years.)

But I was amazed how well the high-tech gear was suited to mapping and surveying with a boat as both the instrument platform and the means of transport.

Some scientists are also skilled boaters, but most are not. So let this be a nudge to think of ways you can use your boating skills to help out scientists on channel mapping, wildlife surveys, pollution tracking, etc.

JustinJam 08-09-2010 01:34 AM

Post out if you ever need a hand. There are lots of us that used to work fish or wildlife or whatever many an agency, university, or non-profit. Often it is just an additional reason to get out on a river. I personally would like the opportunity to help with research that may help to protect or manage a section of river while at same time running it. Thanks for putting on those pics and explanation.

bookmillone 08-09-2010 06:55 AM

Very interesting stuff Chip. Like Justin said, sing out if you ever need a hand as I would love to be involved in such projects if I am able

tony 08-09-2010 11:11 AM


Good work on the data collection. Unless I missed it, you didn't say what you are using the data for. Is this a government or school research project? What is the aim of your study? Just curious since I studied fluvial geomorph in college. It seems like you will have all the data you need to do some really great analysis.

overunder 08-09-2010 11:51 AM

Thanks for the writeup Chip. It looks like Carl was in river nerd heaven being able to run all that gear at once.

Paddle Iraq 08-09-2010 12:30 PM

So what is the point of all this? The Snake in GTNP and downstream to South Park change course so much from year to year that it seems like this info will be obsolete by next year.

freexbiker 08-09-2010 12:45 PM


Originally Posted by Paddle Iraq (Post 197105)
So what is the point of all this? The Snake in GTNP and downstream to South Park change course so much from year to year that it seems like this info will be obsolete by next year.

Wouldn't that be a good reason to map it? To show how much or often the river changes course?

lhowemt 08-09-2010 04:19 PM

Good to hear from you Chip, and as usual you've got some neat stuff going on. Thanks for sharing with us. Any chance we'll get to see some of the data?

ilanarama 08-09-2010 04:31 PM

Very cool!

Chip 08-09-2010 06:24 PM

The PI is Carl Legleiter and his name will lead any eventual publication. He has two main aims, the first of which is to provide detailed ground-truthed survey data for comparison with a remote-sensing channel survey using air-photo analysis.

There's some new software that allows you to compare optical images taken with near infrared and the human visual spectrum, run various filters, and derive estimates of water depth, current velocity, particle size, and other commonly-used hydrologic parameters.

The second aim, more general, is to document the changes in a very dynamic channel and perhaps to reach conclusions about the forces that shape the channel and bars. The high flows this year really shifted things around, carving away at banks and through big bars and islands, with lots of big, live trees falling into the river and being deposited. The reach from Deadman's Bar to Moose is particularly snaggly and braided.

On his handheld GPS computer, he was able to superimpose our track on airphotos from the previous year. Quite often, it showed us floating through the middle of big bars or even vegetated islandsó a clear sign of just how much the river can change in a short time.

I've thought of doing this as a consultant, once I get the degree. If I ever need help, I'll definitely post a notice on the Buzz.



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