Specific runoff data

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Simon Westgarth
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Specific runoff data

Post by Simon Westgarth » Thu May 25, 2017 4:52 pm

I am looking for some very specific runoff data from recent online gauges. The RiverApp goes back 3 mouths, and the NRFA public up until 2015. The info for in between is what I am after. Any ideas please?

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Re: Specific runoff data

Post by Chris Bolton » Thu May 25, 2017 5:16 pm

I suggest a Freedom of Information request to the Environment Agency

Scroll to the bottom of here: https://www.gov.uk/government/organisat ... ent-agency

This is the applicable legislation, I think: http://www.legislation.gov.uk/uksi/2004 ... ion/2/made

You should be able to find the station reference here: https://flood-warning-information.servi ... sea-levels

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Re: Specific runoff data

Post by jmmoxon » Thu May 25, 2017 5:47 pm

Some rivers can be found up to Mar 2017 in:
http://nrfa.ceh.ac.uk/monthly-hydrological-summary-uk

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Re: Specific runoff data

Post by Poke » Fri May 26, 2017 8:53 am

Or just get the data here directly:
http://www.gaugemap.co.uk/#!Map/Summary ... 2016-12-31
For specific dates i think it's probably easiest to tinker with the URL, though if you click on "Graph options" there's options to change the date range there too.

What are you using it for? Sounds like it could be interesting?
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Re: Specific runoff data

Post by Simon Westgarth » Fri May 26, 2017 11:53 am

THANK YOU.

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Re: Specific runoff data

Post by Simon Westgarth » Mon May 29, 2017 7:38 pm

You guys have been great, thank you.

One more question, without writing the EA, is there a location for stage height to runoff rates for each gauge station? As some data is in stage height at locations, and others as discharge in cumecs.

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Re: Specific runoff data

Post by Chris Bolton » Mon May 29, 2017 9:26 pm

What you need is called the discharge curve for the station concerned, also referred to in the NRFA as the stage-discharge relation or the calibration. It varies from station to station, depending on the width, weir shape, etc, so there's no generic answer. Unfortunately I haven't been able to find this data published.

There's more background information at http://nrfa.ceh.ac.uk/ratings-datums which may help if you do need to ask EA.

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Re: Specific runoff data

Post by Dan Yates. » Tue May 30, 2017 8:59 am

Hi Simon, as above you need the discharge curve. We were able to do all the calcs required for the Fairy Glen flow analysis for the Hydro scheme on publicly available data. Tim Burne did most of the preliminary work on this for us and without him we wouldn't have known where to start, it is pretty obscure on the sites where the data is kept. I would contact him direct for advice.

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Re: Specific runoff data

Post by Dan Yates. » Tue May 30, 2017 9:04 am

This is the document prepared by our hydrologist based on the early research done by Tim. It has some of the maths and links in so it may be helpful

https://savetheconwy.files.wordpress.co ... report.pdf

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Re: Specific runoff data

Post by Poke » Tue May 30, 2017 10:35 pm

I know where they are (well, I just found them).

I'll tell you if you give us a clue what it is for. haha :-D
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Re: Specific runoff data

Post by Simon Westgarth » Wed May 31, 2017 10:16 am

Just doing some research. Please send us what you have, as the discharge curves I have could be of higher resolution.

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Re: Specific runoff data

Post by Poke » Wed May 31, 2017 11:51 am

Pfft. That was obvious! I’m interested in what research. Just nosey about all things river levels related really! ha

Anyway, let me know what gauging station you’re looking at and I’ll dig it out for you.
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Re: Specific runoff data

Post by Simon Westgarth » Wed May 31, 2017 3:05 pm

West Dart (Dunnabridge), East Lyn(Brendon) & Erme(Harford) please.

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Re: Specific runoff data

Post by Poke » Wed May 31, 2017 3:42 pm

Weirdly, I cant find the Erme at Harford or East Lyn on here: http://nrfa.ceh.ac.uk/data/search
The Erme at Ermington is here if that helps http://nrfa.ceh.ac.uk/data/station/peakflow/46006

The Dart is here - http://nrfa.ceh.ac.uk/data/station/peakflow/46007
Use the drop-down on the peak flow tab and click “Peak flow rating information” to give you a graph correlating flow and level, and some equations.

Make sure you read the disclaimer though especially if using the equations, as they’re based on the peak flows rather than the normal flows, and can be particularly ropey when looking at low flows.

No idea why they don’t provide the normal flow equations that they refer to aswell.
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Re: Specific runoff data

Post by Simon Westgarth » Wed May 31, 2017 7:39 pm

I also found them, I was looking for a better resolution version of these specific graphs.

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Re: Specific runoff data

Post by Chris Bolton » Thu Jun 01, 2017 6:28 am

At the bottom of the page, below the graph, are the equations that build up the graph - so the resolution can be as good as you like, either replot the graph or use the numbers directly. But accuracy isn't the same as resolution, they are just curved fitted to the data.

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Re: Specific runoff data

Post by Poke » Thu Jun 01, 2017 5:04 pm

Yeah, completely agree with what Chris said. You can get all the resolution you want using the equations, but it won't make your result any more accurate.

That is partly why I was asking what you wanted the data for. As per my comment above, those ratings equations are based on data for 'peak' flows. It would appear that they have a different dataset for normal flows which isn't available online.

That said, these equations seem pretty good at first glance to me from my (somewhat limited) knowledge of the Dart catchment.

For the west dart at dunnabridge i'd use the following:
For 0 - 0.3m use Q = 104.994 * ( h -0.03200 ) ^ 3.591
For 0.3m - 2.5m use Q = 8.340 * ( h + 0.1150 ) ^ 2.461
For 2.5-3m use Q = 3.029 * ( h + 0.1150 ) ^ 3.515

I don't know how au-fait with MS excel you are, but if you enter the level (in metres) in cell A1, then paste the below in somewhere else, it should give you the flowrate (in cumecs) at that level based on the above equations..

Code: Select all

=IF(A1<0.3,104.994 * ( A1 -0.032 ) ^ 3.591,IF(A1<2.5,8.34 * ( A1 + 0.115 ) ^ 2.461,IF(A1<3,3.029 * ( A1 + 0.115 ) ^ 3.515,"too high")))
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