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Observation Wells

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Observation Wells
Answer (Unmark)
6/22/16 5:20 PM
Hi,

I need to add several head observations wells (90 wells) to calibrate my model.
looking at the manual in page 294, seems need to use the pumping tool to add the observation wells, one by one. Is there other way to do this? For example, adding several observations wells from a table?

I read in an old post that extraction wells can be added directly from an IPF file.

Kind regards.

Alfonso
RE: Observation Wells
Answer (Unmark)
6/22/16 6:54 PMas a reply to Alfonso Flaquer.
Complementing the previos question.

When I add observations wells one by one, i don´t understand why tab "position of filters" have the option to set different position of filters and coordinates, like if differents wells can be added in this tab, but there´s no column to set the measured head. That confuse me.

kind regards.

Alfonso.
RE: Observation Wells
Answer (Unmark)
6/23/16 10:00 AMas a reply to Alfonso Flaquer.
Hi Alfonso,

Thanks for your email.

It is not necessary to use the Pumping Tool to add observation/extraction wells to a runfile. It is easy create an IPF in IMOD using the [Edit] [Create IPF] option or alternatively dump your data directly into an IPF file. An example of an IPF file that you can use for the parameter optimization is given below:

10
6
"X-COORDINATE (UTM)"
"Y-COORDINATE (UTM)"
LAYER
MEASUREMENT
WEIGHT
LABEL
0,TXT
351.98 ,1261.02,1,509.12,1.0,P
351.98 , 949.64,1,512.83,1.0,N
359.51 , 540.32,1,519.28,1.0,I
146.07 , 143.55,1,521.96,1.0,S
148.58 , 844.17,1,515.71,1.0,J
655.83 , 653.32,1,518.32,1.0,Q
746.23 , 447.41,1,519.02,1.0,O
849.19 , 655.83,1,517.12,1.0,M
751.26 , 859.24,1,513.17,1.0,E
751.26 ,1055.11,1,508.19,1.0,G

You can enter this IPF file in the runfile via the iMOD ProjectManager or via a regular text-editor.

An IPF that can be used for extraction is given below:

4
6
"X-COORDINATE (UTM)"
"Y-COORDINATE (UTM)"
"Q (M3/DAY)"
0,TXT
351.98 ,1261.02,-100.0
351.98 , 949.64,100.0
359.51 , 540.32,-1500.0
146.07 , 143.55,-2750.32


You can simply add such a file to the runfile and specify the layer number to which the IPF need to be assigned to, in the runfile. Alternatively you can specify the filter screens of your extraction well and let iMODFLOW put the well in the right model layer automatically. In that case you need to specify the TOP and BOT input in your runfile as well.

Kind regards,

Peter Vermeulen
RE: Observation Wells
Answer (Unmark)
6/23/16 8:57 PMas a reply to Peter Vermeulen.
Hi Peter,
Thanks for your prompt reply.
I understand the procedure to assign the extraction wells ipf via the imod manager or via the run file. I have already done and it works fine.

On the other hand, I have two more questions about observation wells.

1) I have already create an ipf file with the measured observations, but i dont know how to enter this IPF file in the runfile via the iMOD ProjectManager. I also don´t know how i can see the differences between the measure heads and the calculated heads.
I would like to be able to change some parameters manually (recharge, permeability, etc), run the model, and compare measure heads vs the calculated heads. The only way to add an compare measured observations vs caclulated is via the parameter estimation?

2) In your example of an IPF file for observation wells for the parameter optimization, I don´t understand what the fields "WEIGHT and LABEL" are for?

I was looking at the manual, page 78 "define measurements", LCol, ZCol and WCol are named in the tab "measurements". Are this columns related to the ones you name in the ipf example?

I also try to find information about pilot points.

Sorry for all this questions!!

Kind regards.

Alfonso.
RE: Observation Wells
Answer (Unmark)
6/27/16 10:02 PMas a reply to Alfonso Flaquer.
Hi Alfonso,

These are your answers to your questions:

1) Yep, that is true, you can only add the measurement whenever you add the PST module. On the other hand, you could manually adapt your runfile and add the IPF file into it, as done below:

d:\IMOD-MODELS\IBRAHYM_V2.0\DBASE_DLD\IMOD_USER\MODELS\IB_V2.0.3_2
20 20 59 0 1 0 1 -2 0 0 0 0
d:\IMOD-MODELS\IBRAHYM_V2.0\DBASE_DLD\MSR\VERSION_2\meetreeksen_erftverband_year\gwms_ilay10.ipf ,2 ,1,2,11,5,12
d:\IMOD-MODELS\IBRAHYM_V2.0\DBASE_DLD\MSR\VERSION_2\horizont\ostw\ostw_fishnet_pnt1000_select_ilay.ipf ,2 ,1,2,3,4,5
1 0 3 0 0 1 0.001 1.0
500 50 0.001 100.0 0.98 1 1.0 25
180000.00,315000.00,240000.00,374000.00 250 0.0 SUBMODEL
ACTIVE MODULES
1 0 (PST)
1 0 !(BND)
1 1 0 !(SHD)

After the simulation iMODFLOW will add extra fields to the resulting IPF file that show the computed differences. In this manner you could manually do a kind of parameter estimation.

2) The field LABEL is obsolute and the field WEIGHT is used to weigh you measurements, so each residual gets weighted in the objective function. Indeed, the LCOL, ZCOL and WCOL are columns in the IPF file that need to contain the LAYER, MEASUREMENT and WEIGHT respectively.

3) The Pilot Points are not yet supported by iMODFLOW v3.3 and v3.4. We believe this will be in the version v3.5, probably autumn this year.

Kind regards.

Peter Vermeulen
RE: Observation Wells
Answer (Unmark)
6/28/16 9:54 PMas a reply to Peter Vermeulen.
Hi Peter,

Thanks for your reply.

Following your suggestion, I've been able to generate the ipf containing the measured values vs calibration values.

Kind regards.

Alfonso.
RE: Observation Wells
Answer (Unmark)
6/29/16 11:05 AMas a reply to Alfonso Flaquer.
Hi Alfonso,

Okay nice ! Good luck.

Regards,
Peter Vermeulen
RE: Observation Wells
Answer (Unmark)
8/5/16 4:03 PMas a reply to Peter Vermeulen.
Hi Peter:

I´m trying to do the same (compare measure heads vs the calculated heads without run the PEST) on iMOD 3.4 and it´s not working.

This have sence to you? I have to change something?

Kind regards.

Alfonso.
RE: Observation Wells
Answer (Unmark)
8/19/16 10:17 AMas a reply to Alfonso Flaquer.
Hi Alfonso,

Residuals will be computed only whenever the iPEST module is activated.

Kind regards,
Peter Vermeulen