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Broads Winter Flooding


Poppy

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On 07/03/2020 at 19:06, marshman said:

No, the real issue this winter is the length of time we have had prolonged rainfall and the amount we have had of it - the marshes are currently performing their job in that they are have been soaking up a lot of the excess like the sponge they are! Fill up your sponge with water and after a point it cannot take anymore - thats exactly what has happened this year.

Another reason why the Thames barrier has recently proved to be totally ineffectual against heavy rainfall flooding in the upper reaches of the river.

Incidentally, I read last week that the Somerset levels have escaped the recent flooding in the West Country owing to the measures put in place over the last 4 years. This work was done, so they say, against the advice of the EA and all the ecology pressure groups.

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20 hours ago, SwanR said:

But what about the effect that would have along the coast? Stop the water in one place and it has to go somewhere else. It’s not just about the Broads if you start to look at measures like this. We see stories of coastal erosion every year too. 

Well, they are about to start building one in Lowestoft  https://www.theyworkforyou.com/debates/?id=2020-01-20e.142.0

As is the Ipswich one ! https://www.bbc.co.uk/news/uk-england-suffolk-47165575

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I don't think the Thames Barrier was ever meant to have that much impact on the Upper Thames - indeed its only usually ever closed against surge tides, although in the floods of around 13/14 they did I believe, use it to keep some of the incoming tide out, so helping the discharge at Teddington.  It was designed primarily, I believe, to prevent flooding in the East End and Central London.

If you look into info on the Barrier you will see that measurements there show when it it was first built, annual sea levels were increasing at around 1.8mm a year, but now its around 3.1mm a year. Its either the land sinking quicker, the Barrier sinking or actually evidence of rising sea waters - I think I know where I would put my money!

The Ipswich barrier isn't really comparable to the Yarmouth issue as thats  only on a tiny scale. It only shuts off the Dock and does not impact the drainage of half of Suffolk.

A Yarmouth barrier?  I suspect in reality they have not a clue about the real impact of one on the Broads as a whole,  which is why they opted for the easier option of raising river banks!!!!!

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13 minutes ago, marshman said:

I don't think the Thames Barrier was ever meant to have that much impact on the Upper Thames - indeed its only usually ever closed against surge tides, although in the floods of around 13/14 they did I believe, use it to keep some of the incoming tide out, so helping the discharge at Teddington.  It was designed primarily, I believe, to prevent flooding in the East End and Central London.

If you look into info on the Barrier you will see that measurements there show when it it was first built, annual sea levels were increasing at around 1.8mm a year, but now its around 3.1mm a year. Its either the land sinking quicker, the Barrier sinking or actually evidence of rising sea waters - I think I know where I would put my money!

The Ipswich barrier isn't really comparable to the Yarmouth issue as thats  only on a tiny scale. It only shuts off the Dock and does not impact the drainage of half of Suffolk.

A Yarmouth barrier?  I suspect in reality they have not a clue about the real impact of one on the Broads as a whole,  which is why they opted for the easier option of raising river banks!!!!!

Thames only tidal to Teddington Wier of course

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the problem with Barriers such as the thames barrier, is that there is only a certain time it can be left closed, or the water coming downstream will flood the areas that the barrier is protecting, if the water level outside does not fall below the level inside, then all you are doing is damming the water and causing potential for flooding upstream, you would be slowing down the rate the water escapes the system, which wont reduce levels upstream.

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5 hours ago, marshman said:

Sadly, Griff, I am not sure hydrographics works quite like that - when they built the Thames Barrier a long long time ago they also had to carry out extensive work in the area, spending a lot around the R Lea. I assume from that is not just a question of spreading all that water across the whole of the North Sea but that it affects local areas far more. I think they have spotted that in the Netherlands too!!

Having cycled, walked and fished the R Lee and lived and worked nearby since the 1950s I am not sure what works you are referring to, very little of the Lee is tidal, from Wormley down it is canalised with the old river inter-twining with the relief channel, the only major works I am aware of was for the Olympics.

Having said that the River/relief channel has been carrying a lot of extra water for months like everywhere else, until we stop building on flood plains and the like all the defences in the world barriers included wont solve a problem that has always occurred naturally.

Fred

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Hi Fred - you are probably right!! I just had a vague recollection that when they built the Barrier they also carried out a lot of work either on the Lea or around Bow Creek area?  Or was that at the time of the Olyympics?   What my comment was meant to illustrate, was that placing a barrier say at Yarmouth, would not impact the whole of the North Sea by an infinitesimal amount but could affect other areas much closer  by!  I still stand by my assertion but perhaps got the location wrong - ooops!!

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all that adding a barrier at great Yarmouth could possibly achieve is higher water levels, if they closed the barrier as the tide was rising at sea, then the rivers would start to rise at that time as they didnt discharge into the sea, if the sea level remained high and the barrier closed, the rivers would still be discharging behind the barrier, and water levels would continue rising. the thames barrier works by stopping a tidal surge, but only for a short time and at a point way above the flood plains of the thames.

basically if there is more water in the system than it can handle, there will be flooding

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23 minutes ago, marshman said:

Hi Fred - you are probably right!! I just had a vague recollection that when they built the Barrier they also carried out a lot of work either on the Lea or around Bow Creek area?  Or was that at the time of the Olyympics?   What my comment was meant to illustrate, was that placing a barrier say at Yarmouth, would not impact the whole of the North Sea by an infinitesimal amount but could affect other areas much closer  by!  I still stand by my assertion but perhaps got the location wrong - ooops!!

Various works have taken part in particular for the Olympics, there was a new shortened cut put through into the Thames at Limehouse linking it with the Regents canal in the late 1960s nothing to do with the barrier.

I do agree with you regarding a barrier at GY though, whatever steps are taken if any it will all be negated by all the extra building especially around the DLR, looking at the fields around there is no where for the water to go.

Fred

 

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48 minutes ago, rightsaidfred said:

Various works have taken part in particular for the Olympics, there was a new shortened cut put through into the Thames at Limehouse linking it with the Regents canal in the late 1960s nothing to do with the barrier.

I do agree with you regarding a barrier at GY though, whatever steps are taken if any it will all be negated by all the extra building especially around the DLR, looking at the fields around there is no where for the water to go.

Fred

 

The fields around the lower Bure, the Yare, Waveney etc are largely water meadows, where the water is meant to go in a flood situation. The EA and BESL have largely prevented that with their works over the last 20 years or so.

I recall the first tidal surge after the work on the Chett had been completed. Yards in Loddon were covered in up to 3' of water, whilst the water meadows lower down remained dry. When challenged, EA engineers proudly claimed that it was exactly as the computer model expected.  :default_icon_clap:

 

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i do note that they have used the map for 1 in 100 year floods as their basis (this is the standard flood risk zone on

the government planning site - https://flood-map-for-planning.service.gov.uk/confirm-location?easting=639873.911&northing=309994.925&placeOrPostcode=acle

not that the 1 in 1000 year boundary is much bigger, mainly that is down to the fact that all of that area is flood plain.

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26 minutes ago, Regulo said:

The EA are giving up on protecting the Broads. Let the sea have them, seems to be the gist of it.

https://www.edp24.co.uk/news/environment/norfolk-broads-flooding-environment-agency-warning-1-6552418

I suspect that giving into the inevitable will eventually come to Broadland. It won't be me but it will be my great-grandchildren who will probably have to learn to live with it. Are salt water marshes really such a bad thing? Sat here I simply don't see an obvious answer. 

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