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What is a good way to calculate the evapotranspiration rate ?

Discussion in 'Irrigation' started by Bluelude1, May 4, 2011.

  1. Bluelude1

    Bluelude1 LawnSite Member
    Messages: 70

    I have been trying to locate a good way to calculate the evapotranspiration rate and haven't had much luck. Any suggestions on where I could find a little bit of additional information on something like this?
  2. dKoester

    dKoester LawnSite Gold Member
    Messages: 3,346

    Search the internet, its there.
  3. Darryl G

    Darryl G Inactive
    Messages: 9,500

    It's not a simple calculation and you may have a hard time finding the data to calculate it. You really need a meteorological station in order to do it, and even then the best you're going to get is an estimate. You could directly measure the evaporation rate relatively easily, but that would only give you information of what it under the specific conditions at the time and would not give you transpiration. My best advice would be to try to do a search and see if you can at least find a range from already existing data/calculations.
  4. Bluelude1

    Bluelude1 LawnSite Member
    Messages: 70

    Ya I am really only looking for an average range. Our weather down here in Southern Florida is pretty static with about a 10-12 degree variation from the daily high & low.
  5. Darryl G

    Darryl G Inactive
    Messages: 9,500

    Do you have an agricultural extension service in your county? They should be able to give you some ballpark figures. The thing is that it depends on the temperature, the amount of sunlight and it's intensity, the relative humidity and the windspeed too, as well as the crop. And it has diurnal (day/night) variations as well since plants generally aren't taking up water at night....not to mention seasonal variations. I had to know all this stuff a long time ago when I took a graduate level hydrology class....long long time ago...lol

    Messages: 18,668

  7. Bluelude1

    Bluelude1 LawnSite Member
    Messages: 70

  8. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,158

    What for? A Lincoln (or better) probe is far more accurate in determining moisture at the base of the plant than any e.t.p. data, unless you got a weather station.
  9. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

  10. hamham

    hamham LawnSite Member
    Messages: 62

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