Evaporation

Discussion in 'Habitat Forum' started by Drakes Landing, Oct 23, 2017.

  1. Drakes Landing

    Drakes Landing Refuge Member

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    Does anyone have experience or know what one should expect (average year) in terms of evaporation on a temporarily flooded impoundment. I have heard varying things and I think it is fairly significant in the Fall when the air is drier etc. but can't seem to find anything that specifically says. When we lose a little water I always get a little worried that we have a muskrat hole in the dike or something else going on (which we have had before). I was at our impoundment on Saturday and it seemed to be a little lower than what I would have expected given the rains we have had this past month. I walked the dike and checked the ditch behind the dike to see if I could see any water flowing/moving out but nothing to be found (if a small leak could be that the leak is now above the water line). At any rate was curious about rate of evaporation?


    Would appreciate any thoughts/feedback. Resources online that describe rate of evaporation???

    Thanks gang
     
  2. jzoo

    jzoo Senior Refuge Member

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    Modelling evaporation is extremely complicated. Ground temp, water temp, wind, sun, ambient temp, humidity level are all factors. That being said, you aren't losing a measurable amount of water due to evaporation (probably less than 1mm per day according to some studies I have read when researching the same issue). Much more is soaking into the ground. I have a 17 acre marsh that i flood with a well (soil is gumbo) and i lose about 1/2" per day. Last year we had a "sinkhole" in the bottom of the marsh and we lost 2" per day. We found it this summer, dug it out and repacked it.
     
  3. Drakes Landing

    Drakes Landing Refuge Member

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    Good stuff jzoo. We flood with a well too and about the same acreage. We were losing water to some rat holes a couple years ago and had those repaired. Basically ripped out levee where multiple holes were created and back filled. It seemed to have stopped the issue but that can easily return which is what I am afraid of. We have deprivation tags to eliminate rats/beavers and have done so over the past several years which seems to have worked as we don't have them wreaking havoc on our impoundment (either burrowing through levees or blocking up water drainage in Spring when we let water out). Man are they a nuisance!

    We will just have to monitor. At a 1/2 inch of water per day that adds up pretty quickly. We have had some good rains but I think the ground probably soaked a lot of that up as we were generally dry most of the year.

    The pump is on and we are preparing to get going here soon. 12'ish days to go.

    Good luck.
     
  4. JFG

    JFG Elite Refuge Member

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    DL, you will "loose" a lot of water right off the get go when first filling your impoundment simply due to absorption. Used to make me think I had riser boards not seating properly until I finally realized what was going on. But add to that all the other things jzoo mentioned and it can add up to more than you'd expect. One thing I've done is ad a very visible depth gauge which I constantly monitor. This has given me a good understanding as to what water I do actually loose to evaporation.
     
  5. Drakes Landing

    Drakes Landing Refuge Member

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    The depth gauge is a simple solution that would definitely help with my anxiety I think JFG. I am going to put something in next weekend for sure. Our pool as some varying slope and topography so it is likely misleading how much water we have really lost at any given time. I just see areas where it has lost (the higher elevation slope areas). It seems we have had a lot of recent rains and had expected more but we were generally dry this year (I think 20+% drier than normal is what my Farmlogs App tells me) so that is likely aligned to your absorption idea.

    We will likely pump up now until mid November'ish and then shut down for a week or two and then crank it back up once the freezes start so we can increase depth (for ice eaters) in addition to using the pump ditch as a hunting pool as well...........those birds really love that warmer water coming down the ditch late in the season. Our behind the levee blind along the pump ditch is our go to spot late in the season no matter what the wind (and when things are froze up). They find and use that hole religiously.

    Can't wait to get started.

    Good luck.
     
  6. jzoo

    jzoo Senior Refuge Member

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    Yep. When calculating how long it will take to fill the marsh each year, I generally figure my first 6" of water will go straight through the ground if it has been dry. (every lake will be different of course but that gives you an idea). So if i'm looking for 6" of water for opening day, i need to figure on pumping 12" or 17ac/ft = 5.5 million gallons in my case. 1100gpm out of the well so it takes about 5 days give or take.

    I have a depth gauge set up so i can track water levels. When not pumping, i lose about .5" per day. When pumping i gain about 2" per day.
    I also have a cellular enabled controller on my well so I can turn it on/off from my phone or internet browser. This is really handy since we only hunt 2-3 days per week and live an hour away.
     
  7. 81arnghunter

    81arnghunter Refuge Member

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    i wish we could afford a well pumping out of the ditch sucks!
     
  8. mrmallerd

    mrmallerd Elite Refuge Member

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    Sure wish I had a ditch to pump out of. Waiting on rain sucks worse
     
  9. Guthook

    Guthook Senior Refuge Member

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    Missouri
    Got a well, wish I had a pond that held water.
     
  10. jzoo

    jzoo Senior Refuge Member

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    You're in Missouri and can't hold water? Must not be on the bottoms?
    How big is your lake, do you ever disc/pack it right before filling?
     

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