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mbarcelo
Review Item 3 - Interim Calibration Results (50%)
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mbarcelo
Meeting agenda
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mbarcelo
Presentation material associated with agenda items.
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mbarcelo
Minutes of Meeting 10 (July 12, 2017).
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mbarcelo
Additional presentations for Meeting 11, July 21, 2017
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tdesmara
Attached is a new set of Kx & Kz maps for each of the model layers from the last PEST run (ecftx03ss case03_7).  Same arrays as those presented in the July 12 meeting, only with a revised color ramp to better show the extremes. 
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mbarcelo
Attached are presentations summarizing K values by layer and near High K lakes.
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mbarcelo
Presentation on transient calibration plan.
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Mark Stewart
Two of three mass balance method for base flow separation articles. A third is behind a firewall and I will have to post that one later.
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mbarcelo
Layer 1 transient model calibration - additional slides presented at meeting on July 21, 2017.
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emcdotomb
The following is for the three peer review panel members (Pete Anderson, Lou Motz, and Mark Stewart( to discuss. I am looking at Layer one (the surficial aquifer system) and in particular the simulated mass balance. The graph (map) that shows L01_RECHARGE_INYR  is very confusing. The term recharge is being used differently then what I am used to seeing. My interest is Polk County. We know that the area of prime recharge is along the ridges. In fact, recharge only averages about 5 to 10 percent of total rainfall. Most of the rainfall is lost to evaporation and what's left travels along the surface of the ground.

Are any of you familiar with USGS publication SIR 2006-5320-Hydrology of Polk County, FL? I am attaching an excerpt from that report that addresses the surficial aquifer in Polk County.

Please address why there appears to be  so much difference between the model output and what is normally presented.

Thanks for your help.

Edward McDonald
Auburndale, FL
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pete.andersen
Responding to Mr. McDonald's August 8 post regarding recharge rates in Polk County.  This is a group response from the Peer Review Panel.

The recharge that is shown in the Layer 1, Surficial Aquifer System map that you show (L01_RECHARGE_INYR, which is slide 21 of the July 13 posting of PowerPoint presentation entitled 20170712_peer_review_ECFTX_03SS_PEST_CALIBRATION_STATUS…art_two_maps.pptx.c161uy.partial) is a “model recharge” which includes water that will be evaporated and transpired by plants that have roots beneath the water table. This model recharge is considerably higher than the “net recharge”, which has this evapotranspiration portion subtracted out:

Net Recharge = Model Recharge – Evapotranspiration

You are probably accustomed to seeing the net recharge. For comparison, please refer to slide 22 (L01_ET_INYR) of the same presentation, which is the net recharge.  You will note that in the Polk County area that the evapotranspiration ranges from about 6.9 to 36 inches per year.  The next slide (23, L01_NET_RECHARGE_INYR) shows the net recharge, which is effectively Slide 21 minus Slide 22.  In slide 23, you will see numbers for recharge that you are more familiar with: we see a lot of green, which is 5-10 in /yr and even some yellow/orange, which represents discharge (negative recharge).

The reason for the complexity is that although the model recharge is a specified quantity, the evapotranspiration actually varies with the computed depth of the water table, and this varies with time. There is more evapotranspiration when the water table is near land surface than there is when it is below the root zone. So, the model recharge is input to the model, as are maximum evapotranspiration rate, land surface, and depth at which evapotranspiration is effectively zero.  The model computes the net recharge at specific times—and this is the number that you are accustomed to seeing.

As a cautionary note, allow us to point out that these results are preliminary as they come from an uncalibrated model. These results will likely change toward becoming more accurate as the model is calibrated.

We hope this is helpful. Please feel free to ask additional questions if this is not clear.

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emcdotomb
Mr. Anderson,

Thank you very much for your very detailed reply. It's been a very long time since I studied the sort of math that is part of the modeling process, so it's not my intention to question every little detail presented to support the model results. I do have a concern about using models for conclusions that are beyond their capabilities. I have been reading a book and papers authored and coauthored by Mr. John E. Doherty. In that book and papers a great deal of emphasis is placed on "expert knowledge" and subjective thinking. This supports my view that complex, environmental modeling is as much of an art as it is a science.

It is a fact that the reason that we have SWUCA and the CFWI effort is because the "traditional" water resource has been over permitted. Who has been in charge of consumptive water use permitting since the early 1970's? The answer is the water management districts. Who is now in charge of producing a model upon which critical water management decisions will be made? The answer is again the water management districts. If we agree that "expert knowledge" and subjective thinking are important in shaping a model, it's easy to come to the conclusion that the water management districts may not be the best choice for producing, interpreting and using an important environmental model.

As peer reviewers, your job cannot be limited to just ensuring that you agree with the techniques used, but you must fully participate in determining which water management decisions the model is most useful. Nick Sepulveda once responded to one of my questions saying that he only provides a "tool"; how it is used is not his concern. Clearly, this is not an attitude that can or should be adopted by you as peer reviewers.

We also must remember that this is not simply an academic exercise. There are real world consequences at stake. In Mr. Doherty's book on PEST, he talks about environmental monitoring as a possible way of mitigating model errors. This may sound good to theorists or ivory tower dwellers, but its likely that millions of dollars will have been spent to test a theory. That is not an acceptable risk to take with tax payer money.

Like it or not the modeling effort with which you are involved will have far reaching repercussions for generations to come. Because of this importance, I will be watching and commenting as the model progresses.  

Thanks again,

Edward McDonald
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