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Transport Obs Package Flag iConcINTP


Rich Carbonaro

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I'm using the Transport Observation Package (TOBS) with MT3DMS in a simple GMS model (v10.0.10) for testing purposes. I noticed that when the Transport Observation Package is active, calculated concentrations at observation locations are not being interpolated from its neighboring nodal points. This is in contrast to how GMS reports concentrations when the TOBS package is not activated. I checked the TOBS input file (*.tob) and noticed that the iConcINTP flag which controls how TOBS handles interpolation is set by GMS to zero (no interpolation).

The benefit of the TOBS package is that it calculates mass fluxes at groups of source/sink boundary conditions. I do not believe that GMS can do this in post-processing without the TOBS package active.

Based on the above, I have two questions:

1) Is there any way to tell GMS to turn on the interpolation in TOBS on so that interpolation is performed? I was able to turn it on manually by saving in GMS, opening the TOBS file and changing the iConcINTP from 0 to 1.

2) I'm wondering if interpolation "on" (iConcINTP = 1) should be the default option in GMS since the output would be more consistent with how GMS does post-processing on concentrations at observation points.

Any insight on this would be appreciated.

- Rich Carbonaro

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Rich

All of your observations are correct. GMS writes the iConcINTP as zero. Since this was implemented so long ago I have no idea about how this decision was made. I will add an item to the user request forum to be able to specify the value of iConcINTP.

Prior to implementing the TOB package GMS would calculate interpolated concentrations at the observation points (this is still done for RT3D as it does not have the TOB package). Having iConcINTP set to 1 by default would be more consistent with how GMS does its own processing of the observation data in absence of the TOB package.

You are also correct that the mass flux information is only available if using the TOB package.

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Thanks Alan - that helps a lot.

I became interested in using TOBS because it has the capability of calculating a "blended" concentration when you have a monitoring well screened across multiple model layers. But, I don't think GMS is writing the *.tob file correctly. If I create a concentration observation coverage using "by well screen" and map it to MT3D, the resulting TOB file does not have the correct proportions from each layer. This is controlled by variable prLayer(i) according to the MT3DMS v5.3 manual, and this variable must sum to 1 for each monitoring well. An example of the TOBS file written by GMS for my model is below (prLayer(i) is in bold-red text):

conc21 -2 40 28 1 -1.0 -0.500000 0.500000 -1.0 0.0
1 1.000000 1 1.000000
conc22 -3 39 29 1 -1.0 0.000000 0.000000 -1.0 0.0
1 1.000000 1 1.000000 2 0.000000
conc23 -4 40 29 1 -1.0 -0.500000 0.500000 -1.0 0.0
1 1.000000 1 1.000000 2 0.000000 1 0.600000
Notice for conc21, that it sums to 2.0. When I check the coverage for this monitoring well the concentration is about 2-times what it should be. Similar for conc22 and conc23.
Something seems off with the algorithm for calculating prLayer(i).
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One additional item that would really improve how TOBS works in GMS: Add the well id to the comment lines in the header of the TOBS input file. For example, the input of *.tob files is shown below. The POINT 1 refers to the first monitoring well in the coverage and "conc0" is assigned as the name (presumably so as not to have any invalid characters or spaces).

# TOBS package input file (GMS - 6.0)
#GMSCOMMENT 1bef6b22-ea40-4722-8952-20a675a4cc41 POINT 1 280.0 615.0 conc0
#GMSCOMMENT 1bef6b22-ea40-4722-8952-20a675a4cc41 POINT 1 280.0 615.0 obs1
#GMSCOMMENT 1bef6b22-ea40-4722-8952-20a675a4cc41 POINT 1 280.0 615.0 obs2
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  • 1 month later...

Thanks Alan - that helps a lot.

I became interested in using TOBS because it has the capability of calculating a "blended" concentration when you have a monitoring well screened across multiple model layers. But, I don't think GMS is writing the *.tob file correctly. If I create a concentration observation coverage using "by well screen" and map it to MT3D, the resulting TOB file does not have the correct proportions from each layer. This is controlled by variable prLayer(i) according to the MT3DMS v5.3 manual, and this variable must sum to 1 for each monitoring well. An example of the TOBS file written by GMS for my model is below (prLayer(i) is in bold-red text):

conc21 -2 40 28 1 -1.0 -0.500000 0.500000 -1.0 0.0
1 1.000000 1 1.000000
conc22 -3 39 29 1 -1.0 0.000000 0.000000 -1.0 0.0
1 1.000000 1 1.000000 2 0.000000
conc23 -4 40 29 1 -1.0 -0.500000 0.500000 -1.0 0.0
1 1.000000 1 1.000000 2 0.000000 1 0.600000
Notice for conc21, that it sums to 2.0. When I check the coverage for this monitoring well the concentration is about 2-times what it should be. Similar for conc22 and conc23.
Something seems off with the algorithm for calculating prLayer(i).

Just wanted to check in to see if the prLayer(i) bug has been fixed.

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This bug has been resolved, and I have verified the fix in the 19 Nov 2015 build of GMS 10.0.12. We are working on getting the nightly build and GMS version download links updated on our website, but if you would like a link to download the "19 Nov 2015 build of GMS 10.0.12" installer then please email support at support@aquaveo.com and we will get you the installer.

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