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Old 18-01-2006, 10:19 PM posted to rec.ponds
Galen Hekhuis
 
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Default Does a pond "breathe"? Is it important?

I may not use the proper terminology, but if anyone can make heads or tails
out of this and responds or tells me where I can find more information I
sure would appreciate it.

There seems to be a sort of local water table with respect to ponds. To
put it one way, if you dig a hole in the ground and fill it with water will
the water drain out? If it does, the hole must be above the local water
table. If it fills up with water by itself while you are fussing with the
hose to try to fill it up, I'd say the hole is well below the local water
table. I'd guess unlined ponds behave much the same way. Some are above
the local water table and others are below it or intersect it.

If a pond is normally above the local water table it always must drain into
it, even if only a little. The water flow (granted it may not be very much
at all) will constantly go from the pond into the ground. There are times,
however, (like after a heavy rain) when a saturated ground will actually
result in the local water table being above the pond, and the water flow
will be from the ground into the pond. Depending on the porosity of the
ground and how much rain there was and things like that I could see this
kind of reversal happening several times a month. I realize that this kind
of movement is very slow, is it so minimal in most cases as to not be worth
considering? I can't find anything on it, so maybe it is insignificant.

The other case would be a pond that didn't "breathe," such as one that
intersects the water table. A hard rain might dump 6 inches of water in
the pond, but it would also dump it on the surrounding land, so while the
water in the pond might rise, the surrounding local water table would also
rise by about the same amount, resulting in virtually no flow between the
ground and the pond. Like I say, though, this difference may be
insignificant enough to be safely ignored, but I can find nothing that
addresses it.

The above assumes, of course, that there is absolutely no surface run-off
or anything else involved, something that would horribly complicate this
rather simplistic (and perhaps stupid) question.

Galen Hekhuis NpD, JFR, GWA
We are the CroMagnon of the future