[at-l] raindrops keep falling on my head......

[spiriteagle99 at hotmail.com (Jim and/or Ginny Owen)]

Weary wrote:
>I must confess that, probably unlike Jim, I've never measured a raindrop, 
>nor
>have I even "spent some years learning about things like 
>magnetohydrodynamics

Well, maybe that's why you keep on draggin' bad science through here?  <G>


>However, I do know quite a lot about trails and the erosion that destroys 
>them,
>as I'm sure Jim does, though he seems to be trying hard to keep his 
>knowledge
>secret.

I don't need to keep anything secret - but if I told you some of what I 
know, you wouldn't understand it anyway.  So why should I bother you with 
it?  <G>


>And I am quite familiar with the varieties of rain drops. They range from a
>gentle mist to soil pummeling big drops. All I've ever said about the 
>velocity
>of rain drops is that in a vacuum they would accelerate at the rate of 32 
>feet
>per second,  per second.

No, that's NOT all you've said -


>Yes. Jim. Falling objects in the real world have a terminal velocity. I 
>don't
>have a clue what that might be for rain drops, though I'm quite sure 
>terminal
>velocity varies as the natural conditions change.

Really?  Then why are you telling us that falling raindrops carry enough 
velocity to damage trails?  After all, as you just said - you don't know. 
<G>


>What I do know is that rain hits the earth -- and trails -- fast enough to 
>cause
>soil erosion, a serious problem world wide.

But - but - you just said you didn't know how fast they fall. So you don't 
know enough to make that kind of judgment.  And besides - it's nonsense.  
<G>


>And I know that of the many ways
>found to reduce soil erosion, among the easiest to apply is to minimize the
>disturbance of natural soil and the vegetation that is growing on it.

Really?   Really - sometimes.  But your explanation is faulty.

When a raindrop hits the trail (assuming the trail has no duff or organic 
material on it) there's an initial disturbance.  You've claimed that a 
raindrop will always push particles of soil downhill - but that's not true 
either.  Whether a particle of soil gets pushed downhill, uphill or remains 
stationary depends on the force (energy) of the raindrop AND the angle at 
which it hits the particle AND on which part of the raindrop first contacts 
the soil particle AND the size, mass, shape and orientation of the particle 
AND --a couple other factors.  Either way - the raindrop is absorbed into 
the soil and the top layer of soil gets wet.  Once the top layer gets wet, 
it also becomes more resistant to being moved by any other raindrops that 
might hit it.

Part deux - you've assumed a very large number of raindrops impacting a very 
small area to create your "erosion."  That's a bad assumption.  Even in the 
hard rain that you've assumed as normal (which it isn't), the distribution 
of raindrops is more likely to result in a very small number of raindrops 
impacting any given particle (or any particular point on the trail).  Only 
the most exceptional storms would apply  a significant enough force to any 
given soil particle to move it any distance.  In which case, you'd have 
other problems to worry about.

Part trois - by your own words - most trails are covered by duff, leaf 
litter, etc, therefore the raindrops will not reach the soil particles to 
disturb them.  Instead, the raindrops will be stopped and absorbed by the 
organic material, which, when enough rain has fallen will again wet the soil 
and make it more resistant to movement.  For most of the AT of course, this 
wold be AFTER the raindrops have been intercepted by the tree canopy and 
lost most of the energy they started with - and most of their velocity.

Part quatre - the process of "erosion" is related to raindrops by the fact 
that those raindrops collect and form streams.  If enough raindrops fall, 
then streams form - sometimes small - sometimes large - sometimes  swollen, 
angry and violent.  The streams are what carry off organic material - and 
trail soil. Not the raindrops.  A raindrop (or multiple raindrops) that fall 
and fail to produce a stream will NOT carry off soil particles.  They "may" 
redistribute some of the particles - but it would be a random distribution - 
and not entirely downhill.

Part cinq - once a stream forms in the trail bed, then you WILL lose some 
small amount of soil - even if it's covered by leaf litter, humus, etc. But 
it'll be a VERY small (read infinitesimal) loss.   Even if nobody walks on 
the trail during the time that stream is running.  And THAT is the long term 
erosion that reduced the Appalachians to their present size.  Does anyone 
remember that the Appalachians were once big enough to dwarf the Rockies?

Anyway, if you walk in that flowing stream, your boots, shoes, bare feet, 
alder hiking pole, Leki -  whatever penetrates that stream and "touches" the 
soil underneath will disturb the soil and carry some soil particles 
downstream.  An alder pole is NOT an exception to that.  That's a related 
form of erosion. Also related is that when your foot slips, it will create a 
greater disturbance and release more of the trail soil than the hiking pole 
that would have kept you from slipping in the first place.

Well - how about when the soil is damp (or wet) but there's no running 
stream?  How about - there is no erosion in that case unless you're picking 
up handfuls of mud and throwing them into the woods - or carrying them with 
you.  No stream = no erosion.

Well - sorta.  Anyone who's been around the mountains during snowmelt knows 
that the mountains are not static.  Have you ever listened to the Chinese 
Wall falling - one piece, one rock at a time?  How about Katahdin?  Frost 
heave is one manifestaion of the power of the expansion of melting ice.  
And, given enough time, it can and will take down mountains.  But that's not 
really erosion -

So - what's the point of all this?  Only that "rain" impacts the trail only 
indirectly - and that we've ALL (at least all of those who are still reading 
this mess. Ginny isn't - but then she's smarter than I am) wasted much of 
the last week because Weary doesn't understand that the impact of a raindrop 
(or multiple raindrops)  does not, in and of itself, constitute "erosion"  - 
or that it's a rare storm/raindrop that will move even the smallest soil 
particle far enough to be seen by the naked eye - or that erosion is 
produced only by streams - not by individual raindrops.

How much time, O Lord, does it take to educate someone who doesn't want to 
be educated?

Walk softly,
Jim

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