Irrigation in Noah-MP

[qingling]

I used WRF coupling Noah-mp to simulate irrigation in the 2000. I set an experiment that is only used by flood irrigation method. However, There was big values when I get the Sprinkler Irrigation Water Accumulated (IRSIVOL). It is so confused. I would be very grateful if you could answer the question. Looking forward to you reply!

 

[zhezhang]

Hello, can you make sure about the noahmp irrigation option, opt_irr is on and opt_irrm = 3 for only flood irrigation.
And Where is the study area?

 

[qingling]

Hello, can you make sure about the noahmp irrigation option, opt_irr is on and opt_irrm = 3 for only flood irrigation.
And Where is the study area?

Thank you for your reply! I just used the opt_irrm = 0 (based on geo_em fraction). My study area is in xinjiang, China.
The three images is FIFRACT, MIFRACT, and SIFRACT from geo_em.d02.nc respectively. MIFRACT and SIFRACT in my study area is zero but IRSIVOL's values is big.
Looking forward to your reply! Thanks!

 

[zhezhang]

Thank you for these maps, I think this issue is related to this line in the irrigation code:

noahmp/src/module_sf_noahmplsm.F at e5c0859874407859936739e8be8741f9aed369ee · NCAR/noahmp

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github.com

! If OPT_IRRM = 0 and if methods are unknown for certain area, then use sprinkler irrigation method

It happens on cropland and when irrigation fraction > than IRR_FRAC:
( IF((CROPLU .EQV. .TRUE.) .AND. (IRRFRA .GE. parameters%IRR_FRAC) .AND. &)
but all these irrigation method fraction is 0, then it will choose for sprinkler irrigation by default

I suggest you can look into the spatial distribution of irrigation fraction, cropland distribution, these three different irrigation method, and their discrepancy.
And when you know there is only flood irrigation, you can use OPT_IRRM=3 for flood irrigation only.