KWVR flooded - but now open again

[simon47603]

For the last 18 months or so a Cold blob has appeared and developed in the North Atlantic. This was the first indication that the Atlantic Multidecadel Oscillation (AMO) is switching from its Positive Phase (Warm) to its Negative (Cold) Phase. These phases last over 30 to 50 years and are part of a natural phase. (This has been occurring for Hundreds of Thousands of years, we Humans have no effect on it whatsoever).

 

The AMO affects the Sea Surface Temperature (SST), which inturn effects the position of the Jet Stream. The Cold Blob extends from Canada to the West Coast of Ireland, the seas around the British Isles are still warm. The Jet Stream is skirting around the Cold Zone, and when it hits the Warm Water around the British Isles it is taking a left turn directly over us and heads to towards the Arctic. This is has brought us Storm after Storm

Over the last 2 Months.

 

Paul Homewoods site https://notalotofpeopleknowthat.wordpress.comis a good place, for a better understanding of what's happening.

 

For more on the SST and the Jet Stream have a look here:

https://notalotofpeopleknowthat.wordpress.com/2015/12/29/north-atlantic-ssts-dropping-sharply/

 

If you are interested in how the El Niño works have a look at this:

https://notalotofpeopleknowthat.wordpress.com/2015/12/31/laymans-guide-to-el-nino/

 

When the AMO finally goes Negative, we will see a return of the Cold Winters like the ones we saw from the 1940's through to the 1970's. On the El Niño, it has spiked and it is now showing that it is weakening, I have read that it will be gone by October. What people don't know is that after every El Niño comes a very deep La Niña which means we could be looking at some very cold winters ahead.

[PaulRhB]

As with so many things including our transport system there no easy answer. The solution is joined up thinking from top to bottom of the river system.

1. Don't remove the trees and bogs that catch and slowly release water in uplands particularly.

2. Don't build new road, housing or industrial areas and expect the existing rivers to cope with the rapid run off from paved areas. They need their own bog, woodland or a wider river to control run off.

3. Don't build on the flood plains.

4. Maintain the drainage of human created systems as they usually get a lot of silt run off and as they are usually smaller than a natural river clog up quicker.

5. Accept flooding has always happened in some areas but modern furnishing means the cost of cleaning and replacement is much higher. There's a reason a lot of the buildings in old areas near the river had stone floors and simple furniture on the ground floor.

 

And the main flaw with all these brilliant ideas? It costs money to build and maintain the drainage and there's too many people out there in construction and development authorities wanting a quick buck or result to meet targets which they can do as there's little legal redress or financial penalty.

Point 2 above is responsible for two major flooding problems the railway experiences each year I know of. A new road scheme dumps all its water onto fields which can't absorb the, and this is the important word, EXTRA water so it just runs off straight into the railway cutting!

Ho hum

[The Stationmaster]

Don't worry chaps - it will all become real front page news before long as the Thames a couple of miles above us is on the verge of bursting its banks.  This won't cause any real damage at all as its one of those spots which always used to flood in the spring and it should be the same downstream for quite a distance.  But if so much as a single house has water lapping round its doorstep I can see major headlines and questions in Parliament.

 

The answers to this particular (non) problem are precisely addressed in Paul's post above.

[PaulRhB]

It would be very interesting to survey the areas recently flooded and see what new building schemes upstream, on all feeder rivers and streams, have been built in the last twenty years and consequently what extra capacity was added downstream to cater for it. There will always be a certain factor of nature when either the ground is baked hard and slow to absorb at first or has been saturated by weeks of rain that will cause flash floods. What interests me is that certain places I know that were damaged by flooding a few years back have survived the last two years after more thought was put into protection from scouring at the critical drain points. The flood plains do their work well but where embankments confine water the bridges need regular work to check scour damage and I'm increasingly seeing old bridges up to the top of their arches in news footage suggesting that additional spans are required to reduce the pressure on the older bridge. CK posted pics of the extra flood alleviation installed during the Dawlish shutdown where a huge concrete channel with massive wing walls replaced tubular culverts. That was a welcome forward bit of thinking brought forward as all plans were in place which proves it is possible if there is joined up thinking. I have no doubt the skills are there if a single agency can have the power to stop politicians of all levels interfering and authorising developments because the risk assessment was acceptable, especially when current once in a hundred years predictions are proved wrong. What you do with the new developments already in place is difficult and probably as controversial as letting erosion take coastal houses.

[Butler Henderson]

Its usual practice for new developments to discharge surface water at 5 litres/sec which is apparently the typical rate that ground water seeps out naturally. Collected surface water is taken to underground tanks or on site ponds from where controlled dischrges take place into the watercourse. All of this is designed to cope with most storm conditions but no doubt they were overwelmed. The Enviornment Agency categories land at different flood risks although previous land at a high flood risk can be recategorised such as to developable a result of flood defences being put in place. Pickering for example previously flooded too often but the new flood defences prevented any significant floodin.

[The Stationmaster]

Its usual practice for new developments to discharge surface water at 5 litres/sec which is apparently the typical rate that ground water seeps out naturally. Collected surface water is taken to underground tanks or on site ponds from where controlled dischrges take place into the watercourse. All of this is designed to cope with most storm conditions but no doubt they were overwelmed. The Enviornment Agency categories land at different flood risks although previous land at a high flood risk can be recategorised such as to developable a result of flood defences being put in place. Pickering for example previously flooded too often but the new flood defences prevented any significant floodin.

An interesting little point here is how individual properties dispose of rainwater (and snow melt of course).  Thames Water allow us a small percentage reduction in our bill if we dispose of rainwater on our property without it going into their sewer or mains rainwater drain (we have both in our road).

 

A natural corollary to this would surely be to charge people more if they reduce the amount of natural drainage on their property thereby increasing the run-off to be collected by storm drains. sewers etc?  Thus paving over your front garden to park a car would attract an ongoing charge as would, say, a paved patio which doesn't drain to soakaway within the property.

 

Equally in my view amy proposed riverine flood defence scheme should be thoroughly assessed to establish where the water will go instead and the scheme should be disallowed if all it does is move the flooding to another residential area.

[PaulRhB]

Collected surface water is taken to underground tanks or on site ponds from where controlled dischrges take place into the watercourse. All of this is designed to cope with most storm conditions but no doubt they were overwelmed.

I have no doubt that is planned in some cases but I've seen torrents rushing down roads and car parks and straight off into ditches. I question whether in many cases the development is working as intended though as it seems increasingly that when local councils try to take action the developers tie it down in legal wrangles stating simply they built it as approved. This is certainly the case with some of the road schemes too and the council doesn't have the money to redesign. It seems the corporate world is much better at writing the loopholes into contracts and financing the legal protection of their side

[Phil Bullock]

Some very thoughtful posts on here gentlemen

 

Thank you

 

One might conclude that catchment management for both hydrological and environmental purposes would go some way to at least identifying issues - as The Stationmaster intimates trying to deal with matters locally merely moves the problem .

 

And needless to say all planning applications within the catchment would need to meet the requirements of that management plan or not be allowed.

 

Phil