Re: [Npsource-cbpmodel] Flow Calibration station for James River segment JL7_6800_7070

[Burgholzer, R. (DEQ) <Rob...@de...>]

Thanks Gary - if I wanted to poke around in that, do you know off hand where I'd find the flow files that correspond to that gage?

My best to you, Kelly and Jack,
/r/b

From: Gary Shenk [mailto:GS...@ch...]
Sent: Tuesday, June 02, 2015 11:37 AM
To: nps...@li...
Subject: Re: [Npsource-cbpmodel] Flow Calibration station for James River segment JL7_6800_7070

Rob -

Great to hear from you.

To the best of my knowledge, the James at Richmond is the combination of those two stations and the concentration data set is the weighted average.  Glad to hear that it's helpful to your efforts and that the low flow is good enough and serendipitously biased in the right direction!

Gary Shenk
Integrated Analysis Coordinator
EPA Chesapeake Bay Program Office
410 Severn Ave, Suite 112
Annapolis MD 21403
410 267 5745

From: Burgholzer, Robert (DEQ) [mailto:Rob...@de...]
Sent: Tuesday, June 02, 2015 10:41 AM
To: nps...@li...<mailto:nps...@li...>
Subject: [Npsource-cbpmodel] Flow Calibration station for James River segment JL7_6800_7070

Gary/CBP Modelers,
I have been doing some low flow analysis in the James River and wanted to ask a question about the flow gages for calibration.  Looking at the file input/calib/observed/all_stations.csv, the gage indicated there is the USGS 02037500 which IS the gage that corresponds to that location, however, there is a smallish (always less than 200 cfs) diversion through the Kanwha Canal just above that point that is NOT in any of our withdrawal data sets that we share with you all.

In other words, if one wants to know the actual flow above that point you ahve to add the flow from 02037500 and 02037000 together.  This is a really small difference under all but the lowest of flow conditions -- less than the 1% on average, and only greater than 5% of flow during 4 months during 1984-2005 period.  Nevertheless, during the 2002 drought, from June-September this would amount to a large portion of the flow (>10%) if it is not accounted for.

So, I guess my question is:

1)      Do you account for the Kanawha canal flow (02037000) in the calibration file somehow?

2)      If not, do you have interest in doing so in future version of the model?

3)      If I'm wrong about the flow calibration file, please enlighten me!

FWIW, you guys have always been up front that low-flows are not the highest priority given the intent of the CBP model, but despite that, it really performs quite well - and from a water supply standpoint, UNDER-estimation of flows during critical drought just provides an extra MOS, so that is cool with me.  That said, if this is not already acounted for, it might improve the calibration data set just a wee bit.

Thanks for your attention to this.

/r/b