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bryan
02-19-2008, 02:43 PM
does anyone know how much, if at all, the rain monday may have effected water levels or destroyed snow bridges, etc? not sure how much fell up that way. i'm particularly interested in the pemi area.

thanks.

bryan

DougPaul
02-19-2008, 02:51 PM
Check the USGS river gages:
http://waterdata.usgs.gov/nh/nwis/rt

In particular:
http://waterdata.usgs.gov/nwis/uv?01074520

Doug

Waumbek
02-19-2008, 04:53 PM
Streams and ponds that I haven't seen or heard in some time are running again in Franconia @ 1200'. I got auditory cues on a bushwhack this afternoon that confirmed I was about where I should be. This is always good.

Mattl
02-20-2008, 08:33 AM
Yeah be careful with stream crossings, the deep snowpack that was covered in a thick freezing rain cover helped to let the rainfall Monday just completely run off, so rivers are very high still, but going down. It will be seasonal with only some snow showers this week, so no more rain. -Mattl

DrewKnight
02-20-2008, 11:17 AM
And the level was very high... just a week ago, there appeared to be lots of contiguous ice-bridges (one of my friends was all set to snowshoe up the river, carefully). Looks like most of the deep cover is now gone. I would definitely be very cautious on any bridges that remain.

Waumbek
02-20-2008, 01:53 PM
This is not meant to discuss the rights and wrongs of recent hikers in trouble. Please start another thread if you want to do that. This one is about water levels.

The stream levels in the Presidentials and Dry River area were high enough on Sunday and Monday both to cause the two hikers who got off course into the Dry River area trouble getting out and to frustrate rescuers on foot from getting in to search for them.

It has gotten much colder since then, but the melt must have affected snow bridges.

DrewKnight
02-20-2008, 03:08 PM
Check the USGS river gages:
http://waterdata.usgs.gov/nh/nwis/rt

In particular:
http://waterdata.usgs.gov/nwis/uv?01074520

Cool resource, thanks Doug. I just wish they'd add another column (or line on the charts) that gives some context. It's interesting to know that the gauge height is 5 feet, but what does that mean, relatively speaking?

It would be particularly useful if they added a datapoint for "average for this month", that kind of thing. Still -- good tool for the quiver, thanks!

DougPaul
02-20-2008, 03:37 PM
Cool resource, thanks Doug. I just wish they'd add another column (or line on the charts) that gives some context. It's interesting to know that the gauge height is 5 feet, but what does that mean, relatively speaking?
Gage readings themselves are arbitrary but the data plotted has been converted to cubic feet per second, which is not arbitrary.


It would be particularly useful if they added a datapoint for "average for this month", that kind of thing.
It is already there--"median daily statistic" in green triangles--86 CFS for today (Feb 20).

However, some pragmatics apply: the East Branch of the Pemi drains a fairly large area and is rather wide in Lincoln. Individual streams/rivers feeding it will be smaller and may vary faster or slower than the East Branch. (In general, smaller drainage areas respond faster. But snowmelt is a big factor right now, so southern aspects may have more flow than northern ones, warm sunny days more than cold cloudy days, etc.)

Doug

bikehikeskifish
02-20-2008, 04:24 PM
One trick I have started to do is record the various river graph images as part of my photo collection for a given trip, and that way I can relate it to future trips. Especially helpful for trips with known high-water crossing difficulties, like Lincoln Brook (Owl's Head) or Gale River (Galehead), for example.

For example, on 11/17/07, the Pemi East Branch in Lincoln started the morning near 700 cfps and ended the day close to 500 cfps. Crossing Lincoln Brook, which drains to the East Branch, was doable with caution. The gauge height was 6.5 feet +/- .25 feet for that same 24-hour period.

I suspect that with snow and ice, the flows will be restricted some way and the three-season value(s) may not apply in winter. Ambitious Conditions reporters might consider including those value(s) as part of any description of river crossings.

Tim

bcskier
02-20-2008, 06:54 PM
We did both trails on Tuesday. The first snow bridge on the Ammo had partially collapsed due to traffic I presume occurred during the warm-up on Monday. Every other bridge was rock solid after the cool down.

The one noteworthy rain-related discovery was at Lakes of the Clouds. From the look of things the rain had fallen on top of the already frozen upper lake and filled the basin to a much greater extent than normal. When we tried to cross the ice that now covered the Crawford Path the first member of our group went through up to mid-gaiter. The top appeared frozen but was really slush. We had to detour around the margins of the lake to the east.

In fact the ice flow from the lake was wide enough to have climbed part way up the hut foundation on its north end. It was solidly frozen there. I expect it will soon freeze solid in its entirety but be careful and test it first.

FWIW here's a shot of the lake after we'd nearly completed our circumnavigation of it.

DrewKnight
02-21-2008, 06:46 AM
(In general, smaller drainage areas respond faster. But snowmelt is a big factor right now, so southern aspects may have more flow than northern ones, warm sunny days more than cold cloudy days, etc.)

Hydrology (hope that's the right usage) is definitely a fascinating science... All last summer, my commuting partner and I made a casual study of the flow-rates at the Campton Dam on our daily drive (OK, it's a long and sometimes boring commute, so we make a game of whether the water will be over the dam when we pass; what the temperature will be when we hit the town sign, etc. What can I say? We're simple men...).

One thing we noticed is that the over-the-dam factor wasn't necessarily correlated with the height of the Mad River or recent rains. On a number of occasions, after days of no rain, the level would mysteriously rise, leaving us to wonder if there was some other impoundment releasing farther up the drainage.

bikehikeskifish
02-21-2008, 08:12 AM
Certainly the Merrimack River dam in Manchester controls the water level below it. Some days it's correlated to the recent rains but others it is not. There are more dams upstream too I do believe.

Tim

Silverfox
02-21-2008, 06:00 PM
I can't speak about the pemi basin but we did Hale via Fire Warden's today and the Little River sure was flowing..No potential of dryly getting across at the first 2 crossings..the side brook that you cross was quite interesting enough ..we did not venture up to the third but I can imagine that first step would be tough...Lots of water flowing..no snow bridges..or ice ones for that matter, in evidence

average bear
02-25-2008, 03:24 PM
A couple more links which may be helpful:

http://nws.noaa.gov/ahps/
top page of hydrology and river flooding data

http://www.erh.noaa.gov/nerfc/
Northeast River Forecast Center

http://www.erh.noaa.gov/nerfc/graphics/snowmaps/html/snow_depth.html
In the same area, they have 24 hour snowfall and total snow on the ground
(snow on ground) + (spring thaw) = floods, but it is also useful to know for backcountry travel in winter.

Gary