Author Topic: Irrigation scheme: FAO56 on monthly time step  (Read 2854 times)


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Irrigation scheme: FAO56 on monthly time step
« on: April 11, 2013, 10:44:35 am »
Dear all,
I am working on a model of an Iranian river basin. Simulation will be done on monthly time step. Irrigation users were defined for different crop sequences containing parameters in regard to development stages of crops in days, always FAO Dual crop coefficient is used for definition of crops . Other crop related data is duration of irrigation period in days.
In Iran the Gregorian calendar is not in use. Instead is used a different system of 12 months. New Year is on March 21 on the Gregorian calendar. The first six months have 31 days, and the last five have 30 days each. The final month has 29 or 30 depending on whether or not it is a leap year. Leap years are not as simply calculated as in the Gregorian calendar, but typically there is a five year leap period after every 7 four-year cycles. Year 0 of the calendar corresponds to 621 in Gregorian. I am decided to use a 1000year-shift (1374=2374) to let MIKE Basin work with this calendar.

Q: In general, what are the consequences of using monthly time step? Has the difference in number of days a serios influence on the results?

Any experience in using the irrigation approach of MB is very welcome.


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Re: Irrigation scheme: FAO56 on monthly time step
« Reply #1 on: August 03, 2015, 06:42:06 am »
You understand the mystery of things.

Ricardo Machado

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Re: Irrigation scheme: FAO56 on monthly time step
« Reply #2 on: August 29, 2015, 04:06:35 pm »
Hello Michael_K,

I would say ignore the calendar differences.
As for the time step, it depends on several things:
1) Are you doing a long term simulation (lasting decades)? If you are then it might be acceptable but it also depends on...
2) The accuracy you desire having in the model results
3) How long MIKE SHE takes to simulate with different time steps for your model
4) Which variables you want to observe and how frequently you expect them to change their value in a degree which you'd like to measure
5) How accurate your input data is...

I hope this helps a bit.

Best regards,
Ricardo Machado
Freelance Hydraulics and Water Resources Engineer

Hydraulic Modeler