Winter watering coefficients


#1

Here in Oklahoma the daily ET for dormant bermuda is 0.02 inch per day. How does Rachio take into account the much lower landscape water requirement during the winter? I believe fescue daily ET is 0.06 inch per day here. Obviously these are averages.


#2

You have to adjust that per zone. I set mine up per the defaults, but had to drop it down substantially to keep it from watering more than I need to. I am in a semi-arid high altitude environment, and the grass can survive to the level I like at much lower water levels then is suggested, even by Colorado State University.


#3

Rainfall affects ET, but rainfall is not in the Penman Monteith Equation. Solar radiation, temperature, wind speed and relative humidity are used to calculate evapotranspiration. Many people have a hard time understanding that rainfall amounts are not in the formula. I have set through many irrigation seminars where speakers confirmed this. Oklahoma City covers a 620 square mile area and the ET has minimal variation from one part of town to another.


#4

I don’t know exactly the details you are referring, but I know for sure that I got 1" of rain the other day, and my zones updated to show 110% (which is the upper limit, although that much rain is significant here).

Adjusting my zone’s crop coefficient made a huge impact, though I am sure there is a more technically accurate way to do it. The biggest factor where I am is getting accurate precipitation data. It varies substantially over a few sq. miles.


#5

Download the Irrigation Associaton’s Best Management practices which goes into great detail about ET and landscape coefficients. This document took years to develop by some of the greatest: https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.irrigation.org/SWAT/Industry-Professionals/Landscape-BMPs/SWAT/Industry-Professionals/Landscape-BMPs.aspx%3Fhkey%3Ddfc642d3-723c-4260-b630-a05a039756ea&ved=2ahUKEwiy8JPLjv_cAhVEXawKHc-lDD0QFjACegQIBxAB&usg=AOvVaw1L_9Rfevk4zueAnUg7Ip_m


#6

That’s an interesting document, but it’s really getting into the weeds on a lot of things people with a current system won’t care about.

Perhaps you will find this of interest.

http://extension.colostate.edu/topic-areas/agriculture/irrigation-scheduling-the-water-balance-approach-4-707/

CSU has a lot of good information people here in the West really care about, as water here is Expensive, compared to the bulk of the country.

http://extension.colostate.edu/topic-areas/yard-garden/


#7

@eckirchn Fun fact. That article was seminal for building our flex daily schedule type and we worked with Dr. Chavez at CSU on the implementation :wink:

:cheers:


#8

There is sooo much good material hosted by extension.colostate.edu @franz, that’s good to know. It’s my first source for anything landscape related, but living in Colorado, it’s a must to learn how to live in this environment. It’s a tough environment to fight nature, best to just work with nature.


#9

Yeah, CSU is only an hour from our office so we love the program and proximity, plus I’m a CSU alum.

:cheers:


#10

Hey, @franz! I’m a CSU Alum too!!! But I can guarantee that I graduated WAAAAAYYYYYY before you!!! :beers:


#11

Go Rams! :smile: