Is there a way to calculate this?

Advice
#1

Background: Went on a 7 mile run last Sunday, the water was a little lower than my liking but doable. The nearest gage had spiked a bit on the chart the day before due to some rain the previous day, but has fallen everyday since.



Question: Is there a way to calculate, track, or anticipate the water rise on a given part of the river if you have the gage height, the discharge and the number of miles the section of the river in question is from the gage? Like, if the gage is 4’ tonight, and the discharge is 200 cubic feet per second, and say I want to go paddling 40 miles downstream of the gage. When will the water in the section I want to paddle rise to an acceptable level? And to make you think even more, if there is a confluence in the river past the gage, and I have both gage heights and discharge rates is there a calculation for that?

#2

You need lots more information
Rainfall, historical data and probably other stuff.



Fortunately, your tax dollars have already done this for you. The national weather service has its Advanced Hydrologic Prediction Service.



http://newweb.erh.noaa.gov/ahps2/index.php?wfo=rnk

#3

Local knowlege
Nope you can’t calculate that without a detailed model of the riverbed.

But if you talk to other paddlers or keep a log you will find that you can predict levels for a given section based on past experience.

#4

I can’t help you on your calc’s, but…
we keep a chart of the level and flows of all the popular rivers that we paddle, and over a period of years you can build yourself a nice data base and will know exacty what the condition of the river will be at any given time, (barring a unexpected gully washer).

If you go on the USGS site, you can get historical data and start from there.

Then you have to throw into the mix the fact that the river might be damned with a non scheduled water release.

Cheers,

JackL

#5

gage locations
One river I paddle has the only gage about 200 yards down from the dam(Mint knows which one I’m talking about :-)). Worthless to me, it is good for the creekers. As Tommy said, local knowlege comes in handy. I know about the huge watershed that feeds this river, so after a good rain, even though the gage may not be up to snuff, I know my cl.2 river trippin’ needs will be fulfilled. Another local river with a confluence at the head has gages at various locations, so as I see the progression of water flow cfs’s downstream, I can figure on where to put in and get an idea of what the feeder streams and groundwater are contributing.

#6

Thanks
for all the suggestions. That’s pretty much what I’m trying to do. I have the recent gage heights, and I’m marking on the the report the days I go out and my impression of the section of river at that time, with the hope to be able to discern a pattern to eventually predict in advance which day will be the perfect paddling day for me, especially after heavy thunderstorms.

#7

Hopefully
Hopefully, you can find a down river gage. All you can do is keep an eye on these until you understand how that river reacts. Lucky us, on the Clarion, there are lots of guages. Whenever it rains, I love to check them frequently as I watch the wave move downstream through the gages. Also, there is a dam and when it shows the guage change, you can monitor the water change as it moves downstream. I use the USGS guages on the waterwatch page. You can get information up to 30 days previous to today.



Mostly, just familiarize yourself with the guage available until you learn how that particular river reacts.

#8

Please be careful after heavy …
thunderstorms if you are on the river.

Unless you are proficient at class III-IV water.

I have a trout stream in my front yard, and it is absolutely amazing how it can crest in seconds after a heavy rain storm just a few miles up stream.

We usually hear the roar before we even see the wall of water coming, and we have many times seen a crest three to four feet high, and occasionally higher.

Once you see it it will make a believer out of you!



Cheers,

JackL

#9

short answer
Short answer is, not really. Your best bet is some of the suggestions seen here. Histories are about as good as you will get. I’d go through a long explanation of design water level calculations but it’s really more than you want to see and without a lot of experience can be hard to grasp. It only yields a “design” water level at best, not all that accurate really.



Pagayeur