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This blog is dedicated to explorations of spirit, life, adventure, and people. I hope that it encompasses much more than the actions of people, but rather creates a more complete picture of what it means to be an athlete and a person in the outdoor community.

Tuesday, May 17, 2011

Flow Trends

Kayakers are always trying to figure out how temperature and precipitation are going to effect the flow of rivers. This is my stab at an explanation. This is where the mathy side of me comes out so if you don't enjoy problem solving and understanding things, don't continue. I am so excited I can hardly wait!

Okay, this is a blog, not the journal of hydrology so I am just going to eschew a methods explanation all together.

So the obvious place to start from is that temperatures and precipitation are going to be the driving factors behind changes in flows on a river. So that is what I played with. I made some assumptions, like that celsius is way better than fahrenheit. Also, it is only the change in flow that matters, that snowpack is constant, that rain and snow precip are the same, and probably a bunch more, whatever.

Reading the graph: Look at the blue line first, those are the temperatures. The flow line(red), should follow it perfectly because as it heats up, the more snow should melt, right? If you see a grave difference, look at the green line, that is precipitation. If flows jumped and temps didn't, I bet it rained.

Here is the result: Beautiful beautiful graphs. Who can say hip hip hooray for algebra 1 and some calculus(since essentially we are taking the derivitave of the flow chart for the middle feather)

Units: On the y-axis(the vertical axis) we have some number that represent celcius, change of cfs by the hundreds, and precip in inches, if I changed it to cm the data would look even more compelling.

Red: Change in hundreds of cfs
Blue: Low temp in Celsius
Green: Precipitation in inches

Except for the precipitation jumps the graph follows the low temp closely. There is some variability but for a three hour project it is pretty good.

Conclusions about what effects flows:

1. It does not matter how hot it gets during the day. It only matter how cold it gets. If it stays above freezing all night that is going to impact the flow of the river much more than if it freezes hard then is 70 F during the day, it is much harder to melt a frozen snowpack than it is a slushy one. 

2. All things environmental take a day to hit the river, so the precip and temp are from the day prior, but that way the bumps line up on the graph. You will know that if there is a precip and temp high bump and a positive flow change, that is was actually hot and wet the day before that led to that positive change. 

3. Precipitation is way more powerful but only lasts about a day. If you get rain for a day, it will be gone by the end of the next day.

These data brought to you by Wolfram Alpha and Dreamflows. Thank you for keeping such excellent records. 

Probably more to come on this. I will try to relearn some statistics so we can get a measure on the factors by which precip and and temp effect flow. I sure everyone is just drooling. 


  1. Rain-on-snow might explain the first several spikes in discharge.

  2. that is true. I was wondering why it is such a dramatic increase in flows, that would make perfect sense.