re: how do i stop my water dam from evaporating away in the hot sun?
7 jun 2000
>email@example.com (need2know) wrote:
>>how do i slow down the evaporation of my water dam at the farm...
>>i heard that you can cover it with plastic drink bottles (half full
>>with water to stop them blowing away...
sounds like a good idea. i wonder how long they would last in the sun.
you'd need a lot of them, about 10 2-liter bottles per square foot or
435,600 per acre.
>if you prevent water from evaporating in the sun, you will increase the
>temperature of the water, unless you somehow shade it.
why would that be true or harmful? a pond that's covered with 2-liter
bottles with some water inside would receive less sun and have more heat
loss area if the water condensed on the inside, so it might be cooler.
even if the pond temp increased, it would only have 9.3% of the original
water surface exposed. how much would the sun raise the water temp if
there were no condensation, and how would the new overall evaporation
rate compare with the old one?
>any solution is going to be either costly or obnoxious.
an article of faith? a "solar pool cover" might help, at 14 cents/ft^2,
or some large pieces of uv-greenhouse polyethlyene duct or plastic film
(about 5 cents/ft^2, in rolls up to 40' wide, with a 4-year guarantee.)
the film might be attached to pvc pipe frames to make large pillows with
some water inside, or heat-sealed into smaller ones like the "coverites"
in us patent no. 4,467,786, issued 8/28/84.