Broads Winter Flooding

[Poppy]

Very interesting EDP article.

https://www.edp24.co.uk/news/environment/winter-flooding-on-broads-potter-heigham-ludham-bridge-1-6549600?fbclid=IwAR01CIntZ3zxB4h9I5P73PMAO7fGydmTxmMDyAvWsv3jriKmZ3LrvfK9Uog

[marshman]

No doubt the Southern Rivers correspondent will be adding a post sooner rather than later!

Good to see though, that the article points to the role of the EA. The one its misses though is the IDB which control the dyke behind the Ludham Bridge Boatyard - anyone approach them, and indeed the EA for their views????

They also omit any comment on the exceptional rainfall this winter

[SwanR]

Interesting indeed. I noted the comment about how many less boats they can pilot through PH Bridge each year now compared to the 90s. At that rate maybe the pilot service won't survive and actually hire boats will then never get through.

[Vaughan]

3 hours ago, marshman said:

No doubt the Southern Rivers correspondent will be adding a post sooner rather than later!

I don't know if you are referring to me    but the gentleman in the article obviously never grew up on a flooded boatyard in the same way that I did!

 

[ChrisB]

One has to look no further than OS. Ludham Bridge is on a tidal river with a contour of 0 = Zero. You do not get a 5m contour until to the West, Horning Falgate or North east above Hall Street almost as far as Whitehouse Farm. I seem to remember reading that the Ludham Bridge that was built during the WW1 was to replace the ancient one nearly washed away in 1912. Boatyards that are tidal do have a tendancy to flood. I bet JM (Peter) can remember, like me, some of the problems we had at Itchenor, Bosham and Dell Quay when sea levels were lower than today.

[CambridgeCabby]

Yes The Ant is a tidal river , and Ludham is a 0 contour , however according to the 
Broads authority the average clearance at Ludham Bridge at high water is 8ft6 , this needs to be updated , since November the average clearance has been less than 8ft at low water and during the 2018 season the high water clearance rarely breached the 8ft barrier .

[Vaughan]

I wish my dear departed friend Brian Thwaites were still here to read that article. He could tell you some stories about flooding on boatyards in Wroxham in the 60s. I don't wish to belittle the problem of rising average levels in the least as there is no doubt it is happening but I sense an awful lot of "journalistic" opportunity here.

Just look at one of the photos. He has a bit of water coming up the slip through the boatshed doors and he has had to put a ligger across it so that he can walk over it. Sorry, but that doesn't make an article, even in the EDP. The boats which were stored at the river end of the sheds at Hearts had a patch in the bottom which could be un-screwed, so that the bilges filled up on a high tide, and they didn't float off the chocks!

If you think about it, any traditional Broads yard, where the boats are hauled up into a shed by a slipway, with a winch, is going to be sited in a place which is likely to flood in winter. You are not going to build it on a hill, alongside the church! And all this about having to move the wiring higher up. If Ludham is like any other Broads yard, the plug points would never have been lower than shoulder height anyway.

There are some things in life that one has to learn to live with.

[ChrisB]

I am not sure but I think the bridge clearances are calculated using "chart" datum at a mean Summer atmospheric pressure.  Like all tidal calculations they are very far from the accuracy we have become accustomed to in other parts of our everyday life. So November does not count.

If you were crossing Chichester or Salcombe Bar would you take Reeds Almanac projection of water under your keel as quoted? Same difference! You are responsible for your crafts safe passage.

[marshman]

No Vaughan - not you!

Incidentally I love that bit in your last post about the where you had a hole in the bottom so you could stop them floating away - a commonsense answer to a recurring problem. The number of boats passing through the bridge is also due to a number of factors - just higher water levels generally and also boat design - neither mentioned by the "investigative " reporter!

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. Like a sponge it then only gets rid of the excess slowly and that is what will happen when we have a drier spell. I suspect in the summer the peat will start to dry out as usual - I recall in some winters fairly recently, the peat hardly got wet!  Well it has this year!!!!

Incidentally Chris, I am sure the Ludham Archive ( Woodwose!  ) will be along sooner or later to tell you the original bridge DID nearly blow away completely in 1912, but that I think was a summer storm - that was when Norwich flooded too. I believe the current bridge dates back to around 1959.

[JennyMorgan]

Down South it does appear that we have had less flooding this winter, both in height and frequency. It is the same North Sea that backs up the tides in the rivers so why would up North flood more than Down South? Any clever hydrologists out there? 

[marshman]

Not me!!!!!! Its a bit like trying to second guess the tides - the damn water does not read the tables and is totally inconsistent, especially when you want it to be, however much you wish otherwise!!!!

[JennyMorgan]

3 minutes ago, marshman said:

Not me!!!!!! Its a bit like trying to second guess the tides - the damn water does not read the tables and is totally inconsistent, especially when you want it to be, however much you wish otherwise!!!!

Based on that the tides just have to be female!

[marshman]

You said that, not me!!!!!

[ChrisB]

2 hours ago, marshman said:

 

Incidentally Chris, I am sure the Ludham Archive ( Woodwose!  ) will be along sooner or later to tell you the original bridge DID nearly blow away completely in 1912, but that I think was a summer storm - that was when Norwich flooded too. I believe the current bridge dates back to around 1959.

Absolutely, the present bridge is modern. However I am sure that I was once told by a local sage that the bridge nearly wiped out in 1912, a very ancient bridge was replaced in the middle of WW1 and it is that bridge that todays replaces. That is to say there have in relatively modern times been three Ludham Bridges, but I certainly don't know for sure.

[Turnoar]

Defo not a hydrologist JM but one thing that could be different north to south is sea water incursion, not just a hole in the sea wall, say at Haisbro (as looks possible in future) or Waxham (as discovered by Hickling farmer Peter Blaxell back in the early 90s), but sea water coming in underneath as I understand was apparent when the dredging broke through the ‘crust’ back in the 60s or 70s and allowed some salt water into the northerly broads. What with high tides any extra head of pressure could attempt to balance out broadside? Could also be more housing development north side inadvertently utilising the Bure as a surface water drain? Where does all the surface water from Aylsham go?

[JennyMorgan]

5 hours ago, ChrisB said:

I bet JM (Peter) can remember, like me, some of the problems we had at Itchenor, Bosham and Dell Quay when sea levels were lower than today.

He certainly does! The infamous double tides, influenced by the wind direction around the Isle of Wight, often caused a few surprises, such as at Bosham! 

[rightsaidfred]

You only have to look at the fields that are now lakes to see why there is so much water in the rivers.

One thought that occurred to me regarding the difference between north and south is flow, we all know the impact the wind has on water levels so maybe the constriction where the Bure enters the Yare means that if there is more water coming down the Yare the water in the Bure is being held back increasing the levels further up river from land drainage, just a thought no idea if I am right or wrong.

Fred

[ChrisB]

11 hours ago, JennyMorgan said:

He certainly does! The infamous double tides, influenced by the wind direction around the Isle of Wight, often caused a few surprises, such as at Bosham! 

That really is a high one. It is still a parking lot though. Nothing quite like wading to you car after a pleasant pie and pint in the Anchor Bleu..

 

 

[annv]

If they put a gate/barrier at Yarmouth like they have at Boston it would stop all this flooding by controlling the incoming tide to allow the rivers to drain 24hrs a day instead of the 10 hrs at present there's a ideal spot at end of the quays where you already have two vertical concrete walls a hollow box could easily be floated across at very high tides, it doesn't have to be watertight just restrict the incoming flow and allow the rivers to flow out for a longer time.this would then drain the upper reaches for a longer time, it is working at Boston and london, John

[SwanR]

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. 

[BroadAmbition]

Restricting  the tidal flow going up the rivers at GYA might increase North sea levels by what? 
Point 01 of a millimetre?

Griff

[D46]

30 minutes ago, BroadAmbition said:

Restricting  the tidal flow going up the rivers at GYA might increase North sea levels by what? 
Point 01 of a millimetre?

Griff

Yes but what's More important ??

[ExSurveyor]

1 hour ago, BroadAmbition said:

Restricting  the tidal flow going up the rivers at GYA might increase North sea levels by what? 
Point 01 of a millimetre?

Griff

You probably wouldn't be able to measure the effect on the North Sea.

That old phrase, a spit in the ocean, spings to mind.

[TheQ]

21 hours ago, annv said:

If they put a gate/barrier at Yarmouth like they have at Boston it would stop all this flooding by controlling the incoming tide to allow the rivers to drain 24hrs a day instead of the 10 hrs at present there's a ideal spot at end of the quays where you already have two vertical concrete walls a hollow box could easily be floated across at very high tides, it doesn't have to be watertight just restrict the incoming flow and allow the rivers to flow out for a longer time.this would then drain the upper reaches for a longer time, it is working at Boston and london, John

Wouldn't work,  half the water from the Bure goes under Yarmouth as it's built on a gravel Spit..

[marshman]

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!!