[NatureNS] slacks - when do they refill?

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From: Randy Lauff <randy.lauff@gmail.com>
Date: Fri, 23 May 2014 15:14:29 -0300
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I have posted a picture of the slack here:
http://people.stfx.ca/rlauff/307/PomquetSlack.jpg. One person I asked
locally thought that the slack filled up again with the autumn rains.
That's probably right, but I still can't discount snow melt accompanied by
spring rain. I guess I'll find out this year.

Randy

_________________________________
RF Lauff
Way in the boonies of
Antigonish County, NS.


On 21 May 2014 18:08, nancy dowd <nancypdowd@gmail.com> wrote:

> Maybe it is just evaporation. Water accumulates in the leaf-lined slacks
> in the Spring (rain and melt) and eventually warming temps and strong sun
> evaporate it until it is empty. Over the summer heat and sun manage to keep
> up with the rainfall not allowing it to accumulate for any length of time
> (it must be hot down in those slacks). Then once the cooler temps and less
> intense sun of Fall take over rainwater can accumulate once again in the
> slacks until it freezes.
>
> Just a guess.
>
> Nancy
> On 2014-05-21, at 4:39 PM, David & Alison Webster <dwebster@glinx.com>
> wrote:
>
> > Hi Randy & All,
> >     I had imagined these dunes to be bare sand. With tree cover on the
> peaks and presumably none on the slacks there is another effect that will
> increase effective ppt in the slacks; sublimation on the tree canopy in
> calm weather and selective snow accumulation in treeless areas (roads,
> glades, etc) in windy weather due to less turbulence and less speed over
> glades..
> > Yt, DW
> > ----- Original Message -----
> > From: Randy Lauff
> > To: NatureNS
> > Sent: Wednesday, May 21, 2014 9:57 AM
> > Subject: Re: [NatureNS] slacks - when do they refill?
> >
> > Thanks folks,
> >
> > I haven't been there in winter, despite my being in NS now for over 20
> years.
> >
> > Here's the landscape picture though. Picture an accordion, partly open
> lying on its back. The bellows represent the dune system at Pomquet, there
> are peaks and troughs (slacks), and precious little other elevations going
> on. At the slack in question, the surrounding peaks of the dunes are
> dominated by white pine and oak, with other trees as well.
> >
> > Fred asked, if the dunes are sandy, how are they holding water in the
> first place? Basically, I think there is leaf litter which may be
> accumulating in the slack to slow the water seepage. Further to Anne's
> email, the slack in question is well back from the salt water, I suspect
> there is no salt to speak of in that water. Mosquitoes are there in the
> billions, peepers are deafening, both suggesting fresh water (though I
> realize a few mosquitoes can tolerate brackish water).
> >
> > Randy
> >
> > _________________________________
> > RF Lauff
> > Way in the boonies of
> > Antigonish County, NS.
> >
> >
> > On 20 May 2014 18:24, David & Alison Webster<dwebster@glinx.com> wrote:
> > Hi Randy & All,                            May 20, 2014
> >     I don't have a clear picture of the topography, either dune or
> inland, but one possible source of water in the slacks is drifting of snow
> into pools.
> >
> >     In woods south of Kentville, where I used to walk in winter, pools
> in woodland cradlehollows of swampy sites never froze. With 2'-3' of snow
> on the ground, the air cone was typically about ~1' across at snow level
> and 4" across at water level. Even at -20o C, with heavy snowfall, 60 mph
> winds and drifting snow  there would be no hint of ice. From the viewpoint
> of ppt per unit area these cones act as black holes; snow blows into them
> but, soon being water, can not escape. These air cones were absent when
> snow was not deep enough to act as a good insulator. With sufficient snow
> cover drifted ~level over the swamp, the soil at the base of cradlehollows
> would warm sufficiently by ground heat from below to melt overlying snow
> and eventually generate one of these air cones.
> >
> >     If these pools were sufficiently above the water table then they
> would tend to be transient but, in most soils (given sufficient iron and
> decomposable organic matter), infiltration rate at constant head will
> gradually slow due to formation of a local iron pan over decades or
> centuries. This effect interested me because ortstein is sometimes very
> scattered; patches 3-4' wide and 10-15' apart and these pools that collect
> below air cones could account for this. Also prolonged wetting will slake
> any soil aggregates and decrease infiltration rate.
> >
> >     Getting back to dunes, in the idealized case of parallel linear
> dunes and linear slacks and  in deep snow conditions I would expect linear
> narrow pools at the base of linear narrow trenches in the snow; V-shaped
> deposits of ortstein if dunes are stable and not advancing.
> >
> >     Have you been there in winter and if so does any of this register ?
> > Yt, Dave Webster, Kentville
> > ----- Original Message -----
> > From: Randy Lauff
> > To: NatureNS
> > Sent: Tuesday, May 20, 2014 4:20 PM
> > Subject: Re: [NatureNS] slacks - when do they refill?
> >
> > Thanks Fred, but in a dune system, wouldn't that mean that the slacks
> would be less than half full with water? These are sand dunes...very
> porous, so I'm suspecting water leaching in from the hills of the dunes
> into the slacks just couldn't fill them. This is unlike the condition in
> vernal pools where there can be ample elevation around from which water
> could leach in to the pool area. I'm thinking there has to be a significant
> rain or snow fall to fill them.
> >
> > Randy
> >
> > _________________________________
> > RF Lauff
> > Way in the boonies of
> > Antigonish County, NS.
> >
> >
> > On 20 May 2014 15:30, Fred Schueler <bckcdb@istar.ca>wrote:
> > On 5/20/2014 2:18 PM, Randy Lauff wrote:
> >
> > Between several of the dunes at Pomquet Beach, Ant. Co., the slacks (the
> > troughs between dune crests) fill with water, but by summer are dry. I
> > guess I've just never been there at the right time to see when they fill
> > again...it can't be just from winter melt water, since the slacks are
> > almost full (and snow melts to about 10% its volume as water). Do the
> > autumn rains fill them again, or the spring rains? Or is it a
> > case-by-case scenario, which I'd just have to monitor?
> >
> > * I had the same thought about vernal pools at the CARCNET me