As a follow-up to the preceding article, We have just received this very useful memorandum from one of our members. Entitled: Getting the Best out of EA Flood Warnings, it is well worth viewing if you wish to keep abreast of real time flood risk:

To see the Flood Warnings, go to www.environment-agency.gov.uk

In “At home & leisure”  go to “Flood”.

I have found that searching for “Local Flood Information” by post code or town is confusing, because of out of date warnings and some that seem to conflict with each other. It is also laborious for getting an overall picture.

I believe that the “Live flood warnings map” in “National Flood Information” is useful, and quicker. Zoom into the area you want, and click on a marker pin.  Click on “More Detail” which will bring up the latest warning.

Note that you can select :
Severe Flood Warnings / Flood Warnings / Flood Alerts / no longer in force.

You can then scroll up or down through the warnings to get the overall picture. They seem to be in update-time order, and to some degree moving downstream.

At present, at 07:00 on Sat 11 Jan 2014 the river is stable above Windsor (Maidenhead to Windsor benefiting from the Jubilee River Flood Relief Scheme). Below Windsor it is rising slowly, generally above 2012 levels but below or approaching 2003 levels. At Datchet and Old Windsor it will rise slowly over the weekend, but is not expected to reach 2003 levels.

At Chertsey and Laleham it is not expected to rise in the next 24 hours (possibly due to the river running off downstream,  or maybe it would rise a little when the latest flush reaches us from Windsor?)

From Molesey down there are references to the tide (in flood flows a high tide can reflect above Teddington Lock.) and whether the Thames Barrier will be closed for particular tides (they can close the Barrier at or near low tide, and the river flood water will collect behind it, to be released when the Barrier is opened as the tide falls.)

It is useful to get the overall picture, to try to see what is coming to us from way upstream. The levels change so slowly that the local warnings do not seem give that, until they start to compare the current event with previous floods.

NB 1 There can be an influence due to flood flows from the Colne Brook and Colne  at Staines,  from the Wey at Weybridge, and the Mole at Molesey (though the last should not affect us greatly, if at all.)

NB 2 A new storm or prolonged heavy rain on a saturated / flooded catchment can cause a new flood to travel down the river. This may or not be a problem, subject to any dry period in between allowing the earlier flood to drop.

NB 3 In the EA website, in  “National Flood Information” there is a Met Office 5 day weather forecast.

Pat Brady

11 Jan 2014.