Topic: Is there an *easy to use* spreadsheet/software to calc evapotranspiration?

[NeverDie]

I'd like to do some "what-if's" to get a feel for the sensitivity of the different parameters.

Preferably, the spreadsheet/software would take the input parameters in the same format as is typically displayed on US weather stations (i.e. not in metric).

[Bushman]

Everything you ever wanted to know about ET.  http://www.fao.org/docrep/X0490E/x0490e00.htm#Contents  And a handly little program to calculate it.  http://www.fao.org/nr/water/eto.html  Now the Holy Wars can begin as to whether Penmann-Monteith is the best model or not. 

[NeverDie]

Unfortunately, it's a DOS program, and also doesn't seem to like running on a 64 bit machine.  It failed to install under Windows 7.  Then, my first attempt at getting it to work in a Microsoft virtual machine (for backward compatibility) failed.  Before I potentially waste a lot of time fussing with it trying to get it to run, any other suggestions?

[Cutty Sark Sailor]

I just use CoCoRaHS 
http://cocorahs.org/Content.aspx?page=et
This'll be third year. Beautiful.
http://cocorahs.org/ViewData/ListETReports.aspx

Mike

[NeverDie]

I just use CoCoRaHS 
http://cocorahs.org/Content.aspx?page=et
This'll be third year. Beautiful.
http://cocorahs.org/ViewData/ListETReports.aspx

Mike

I gather you're using the type you need to read and refill manually, rather than a more automated one?  At a 12 inch water depth, it looks like the manual version could last 3-4 weeks between refills during the hottest months here, and presumably longer than that during other months.  Can it be operated that way?

[Cutty Sark Sailor]

I just use CoCoRaHS 
http://cocorahs.org/Content.aspx?page=et
This'll be third year. Beautiful.
http://cocorahs.org/ViewData/ListETReports.aspx

Mike

I gather you're using the type you need to read and refill manually, rather than a more automated one?  At a 12 inch water depth, it looks like the manual version could last 3-4 weeks between refills during the hottest months here, and presumably longer than that during other months.  Can it be operated that way?

Yes, the ETogage uses distilled water... and operates with a ceramic cup, and 2 covers that simulate crops. CoCoRaHS uses a 'lawn' reference, but other reference covers ( alfalfa, e.g.) are available. I don't know where you're located, but here in central KY the highest ET for one day so far has been about 0.37" or so. Right now, it's running about .05 to .08 daily. As the season warms, and depending on clouds, other conditions, she'll settle into a 0.15-0.30" pattern. A second station in southwestern KY records similar, as do a couple in southern Indiana... I usually fill the gauge somewhere around the 9-10" mark, but they can be refilled anytime, you just transmit your 'refill' level to the server... bout a simple as it gets.
I may refill mine about 2- 3 times yearly depending on when winter returns. The ceramic may break if it freezes, so it's not used during winter weather. I'll bring it inside if the temp is forecast below freezing, setting it back out as appropriate.

There is an electronic model available... CoCoRaHS observers get the devices for slightly more than 50% of retail. Even so, the ceramic cup, and its 2 coverings are very expensive innovations with years of R&D, so the devices are not 'cheap'. They have been used for over a decade by farmers in the Midwest and high plains, I understand.

I figure mine paid for itself the first season in water bills trying to keep my lawn's very thin topsoil moist on this hillside. I had watered many times previously that hadn't been necessary, I discovered.

[NeverDie]

I'm in Austin.  The peak months the ETO might be around 3" per week.

2-3 refills per year isn't bad.  If I were to go this route, I'd probably want to automate by adding a water level sensor of some kind (most likely using an arduino).  I looked at the ETGage previously, and If I recall correctly, it has a goretex membrane, so rain water never adds back to its reservoir.  Is that right?

For better or worse, this year I've decided to try soil moisture sensors for controlling turf irrigation.  I realize its not a popular choice (and maybe for good reason), but I have some wireless sensors arriving tomorrow, and that's the path I'm heading down.  So, my interest in ETo at present is to use as a cross-check, to catch and flag soil moisture sensor faults before they get out of hand.

[Cutty Sark Sailor]

I'm in Austin.  The peak months the ETO might be around 3" per week.

2-3 refills per year isn't bad.  If I were to go this route, I'd probably want to automate by adding a water level sensor of some kind (most likely using an arduino).  I looked at the ETGage previously, and If I recall correctly, it has a goretex membrane, so rain water never adds back to its reservoir.  Is that right?

Correct. I didn't remember it being goretex, but it is a replaceable part, as it deteriorates. (I stretched my first one for two seasons, but hereafter will replace yearly, as recommended) The canvas 'crop' simulator is washable... There is an electronic version of this device... about twice as expensive.

[NeverDie]

If I recollect, the crop simulator is made from canvas.

WeatherYourWay has it priced at $222 presently.  So, I guess CocoRaHS members get it at $111?

It looks as though they may have stopped selling the electronic version.  It's still listed on the etgage.com website, but I don't see it WeatherYourWay.   Last time I checked, the electronic version was priced very high (forgetting now, but around $1,000?), which didn't seem to make a lot of sense, given the alternatives that exist.

[Cutty Sark Sailor]

If I recollect, the crop simulator is made from canvas.

WeatherYourWay has it priced at $222 presently.  So, I guess CocoRaHS members get it at $111?

It looks as though they may have stopped selling the electronic version.  It's still listed on the etgage.com website, but I don't see it WeatherYourWay.   Last time I checked, the electronic version was priced very high (forgetting now, but around $1,000?), which didn't seem to make a lot of sense, given the alternatives that exist.

That is the CoCoRaHS negotiated price that Lucy (WeatherYourWay) and Colorado State worked out with ETgage ... retail is something over $400. The Electronic version is only available directly from ETogage, and you're correct.. the electronic version was quite expensive, I was thinking about $700 retail. Not much demand would be one reason for high cost.

[NeverDie]

Unfortunately, it's a DOS program, and also doesn't seem to like running on a 64 bit machine.  It failed to install under Windows 7.  Then, my first attempt at getting it to work in a Microsoft virtual machine (for backward compatibility) failed.  Before I potentially waste a lot of time fussing with it trying to get it to run, any other suggestions?

As there are no more suggestions, I'll look in storage and see if I can find a sufficiently ancient PC that will run it...

[NeverDie]

By the way, I also tried running HRPM.EXE (which also looked promising):  http://biomet.ucdavis.edu/Evapotranspiration/HRPMexe/HRPM.htm

However, it too doesn't like 64-bit.