Pond Evaporation

[roysallis]

Quite some time ago there was a post concerning pumping water into a pond to keep the water level up. I think there was a formula to determine how much water is lost from evaporation based on the size of the pond. I tried a search but didn't find it. Can anyone help? Thanks.

 

[Mike_Dumond]

Morning Roy. I think you'll find it a little hard to figure evaporation rates. You have to take into account the water temp, the air temp, the relative humidity, size of the pond, height of waves if there is a pond, type and amount of vegetation in the pond to name just some of the factors.

What you might want to do, is record the pond level over time, and come up with an approximation of water loss. Then size your pump accordingly. You can use a float type switch to control the pump. Probably not much help, but in my defense, I've only had 1/2 cup of coffee so far today.

 

[rmorgan]

Roy--

We had 10 hot weeks without rain this summer and our clay pond dropped about 16", which is about .2" per day . . . if you're losing what seems to be a lot of water, might think about looking for leaks.

 

[gmason]

roy, I'm a little confused with your question, are you in a big drought condition there? We were most of this year here in NC, now though we're on the + side for the year and expecting several more inches today.

How is your pond feed naturally? Is it just the rain that falls into it, or is it feed by a stream or spring? My pond is feed from runoff from surrounding home sites and roads. I have one 18", and two 12" pipes feeding it. Here's a link to an picture that shows the outflow pipes(3x12") <A target="_blank" HREF=http://www.tractorbynet.com/cgi-bin/compact/showthreaded.pl?Cat=&Board=projects&Number=37728&page=&view=&sb=&o=&vc=1#Post37728>http://www.tractorbynet.com/cgi-bin/compact/showthreaded.pl?Cat=&Board=projects&Number=37728&page=&view=&sb=&o=&vc=1#Post37728</A>

I was 20" low this summer and with a 5" rain event was overflowing 3 weeks ago. I think the important thing is to have good inflow to begin with for a pond, if not then you have to resort to outside sources for the water(well, pump from another creek/pond).

gary

 

[roysallis]

Thanks for the replies. I have a pond about 1/4 acre that is fed from rain and runoff. Therefore, the water level is not very constant and does drop quite a bit in the summer. I was wondering how much water I would have to pump in to keep the water level constant so I figured I would need to know how much water would have to be pumped in to overcome the evaporation.