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Is It Possible To Have Some Control Over River Water Levels?


Thiswan

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I was thinking if any thought has been given to having some sort of control lock/barrier at Great Yarmouth to limit excessive tides as it seems that craft that could normally get under Potter Heigham and some other bridges can no longer do so and I believe some people are also experiencing more flooding than ever before. It would have to allow vessels to pass in and out to the sea of course. How such a scheme would be funded I have no idea ;) I suspect this subject has been broached before but I haven't been able to find any details.

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it would be very difficult to do so,  there was a hydrographic survey some years ago.

That showed more water came down the rivers than flows out of the GY river mouth,  it was found a large amount of water flows out under great Yarmouth  as its built on a gravel spit. 

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I think there's no way such an idea would happen.Indeed there has been talk about allowing flooding to occur in parts of the broads,in the main close to Potter.Also the cost,my experience of the broads if such an idea to happen then all concerned would no doubt argue about the cost.

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9 hours ago, Thiswan said:

I was thinking if any thought has been given to having some sort of control lock/barrier at Great Yarmouth

Indeed it has!

In the mid 70s there was a very serious scheme to build a flood barrier across the Haven at Gt Yarmouth. This was about the time they were building the Thames Barrier and so Norfolk wanted one too! It very nearly got built but in the end public opinion (including mine) won over and it was cancelled. What was the reason we were against it? Because it would be fine at stopping surge tides but once it was physically in place, it might be used by all sorts of environment "experts" who would say "Why don't we use it to raise the overall level by 4 inches?" Or alternately - "Why don't we use it to drop the level by 4 inches?"

Nowadays, in the upper reaches, we can see clearly how much of a drastic difference that 4 inches can make!

We also saw recently that the Thames Barrier is completely ineffectual when it comes to rainwater flooding in the upper reaches and that has the same effect on the Broads.

There are many who say that the lower Bure needs deeper dredging to get the flow of water out to sea and I am one of them but the more we discuss it, I am not so sure it is the single solution, on its own.

Personally I believe that the problem started when they began to "protect" huge areas of meadow by building flood banks so that the land could be given over to arable crops. The problem was that those meadows had been deliberately used as washlands, to absorb the water from surge tides.

Now that these large tracts of land are once again being returned to grazing meadow I don't see why parts of the bank cannot be lowered to allow them once again to become washlands. I believe we would see a big difference if that happened.

 

 

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If my broads history serves me right and this is going back some time, when I used to talk to the Herringfleet marshmen back in the 60's.

That talks of some sort of seawater defence scheme has been mooted since the turn of the 20th century, with talks of lock gates or some form of barrier at Haven bridge or at Breydon.

I also remember the 1970's argument and the ill fated 2011Lowestoft company which came up with a surge generator and barrier all in one

I remember parts of the meadows along the Waveney between burgh castle and St Olaves. being flooded during the winter with silt dredged into it, so that the nutrients from the silt could grow the grass during the spring.Pumps would appear on barges and put the water back into the river around march time, by june the grass was as green as you had ever seen it. This must have happened all along the rivers with small enclosed fields capable of holding large amounts of water 

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Whilst I would hate to disagree with Vaughan, (I think that what he says is very sensible,) my greatest concerns with that is that a lot of the overflowing water these days may be brackish. There is no doubt that the brackish water now comes further upstream these days, probably because of the banks, and I fear that this could upset the balance of wildlife - not the big stuff but the tiny stuff lower down the food chain. Bugs and downwards!!!

It is very noticeable that when any of the marshes owned by the Wildlife Trusts etc are returned to normal levels, they always restore them with an extra dyke to keep them entirely of fresh water.

Incidentally there is an overflow into the Halvergate marshes just by the bridge over the New Cut but I cannot think of any others

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2 minutes ago, marshman said:

Incidentally there is an overflow into the Halvergate marshes just by the bridge over the New Cut but I cannot think of any others

Hardley Flood on the Chet is a washland, but is more of a permanent one, which becomes a mudflat at low tide. A haven for waterfowl, all the same!

I think what Marshman says is also sensible, but I am remembering why the deep dyke drainage was done in the first place :

A field which grows arable must have a lower water table, hence the deeper dykes but it is also very sensitive to brackish water. Once such a field has been flooded, they say it cannot grow arable crops for at least another 5 years. This is why the farming lobby put so much pressure on Parliament and others, to have this flood protection put in place.

Grazing water meadows however, have a higher water table and the grass is not badly affected by the brackish water. These old washlands  were nothing new - they were an essential part of the system of reclaiming the marshes, for hundreds of years.

I wish Barry Johnson of St Olaves were still with us. He would soon tell us all about it!

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Thinking of my good friend Barry Johnson, who was one of our most knowledgable Broadsmen, I remember a story he told us one day at Blakes, in the mid 70s, about a conversation he had with the local River Inspector.

It seems that one of the Commissioners' workboats had gone aground on what seemed to be a submerged sandbank, on the inside of a bend somewhere upstream of the Waveney River Centre. They were going to send a dredger up there and dig it out.

Barry said "You can't do that! That has been there for donkeys' years and was put there as a surge protector. It is meant to stop too much water from going further upstream if we get a surge tide." They didn't believe him and so they sent a dredger up there and dug it out.

Sure enough, that winter there was a surge tide and it promptly flooded Beccles! The road across Gillingham Dam was cut off for several days, so I heard.

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11 hours ago, Stationerystill said:

I agree with Vaughan. I also wonder if it is a case of boats getting bigger, stopping passage under bridges, rather than the water getting higher.Martham Boats seem to get under Potter Heigham bridge.

 

Whilst boats are indeed getting bigger, it needs to be remembered that boats which used to be able to get under regularly, no longer can. I have often argued that the reduction in dredging of the lower Bure was responsible though flood alleviation works have also been  talked about so I bow to local knowledge.

I do have a question though, to those who remember the days of being able to moor at Marina Quays. When the lower Bure was thoroughly dredged, did the tide rip through there (from the Quays to Breydon) at the speed it does these days?

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12 minutes ago, Vaughan said:

Thinking of my good friend Barry Johnson, who was one of our most knowledgable Broadsmen, I remember a story he told us one day at Blakes, in the mid 70s, about a conversation he had with the local River Inspector.

 

Barry Johnson

Now there is a blast from the past

One of the legends of the marsh. Oft found in the bell at St Olaves, or the queens at Haddiscoe.

 

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If they constructed a floating box barrier/door that would be floated across the channel only on very high tides at the new bridge they are going to build it would only be able to restrict/slow high water levels coming in there for stopping flooding when the flow flows out at ebbing tide the box would then move/float away from bridge back to its resting place this would redress Vaughn's and others concern that it would be used to maintain a higher level of water permanently but still prevent a too high incoming tide and salt incursion as well as being relatively cheap to construct and could also be made locally. John

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15 minutes ago, MauriceMynah said:

Whilst boats are indeed getting bigger, it needs to be remembered that boats which used to be able to get under regularly, no longer can. I have often argued that the reduction in dredging of the lower Bure was responsible though flood alleviation works have also been  talked about so I bow to local knowledge.

I'm definitely not qualified to speculate why, but certainly a lot more used to be able to regularly get under both of the troublesome tonnage bridges on the North and now no longer can.

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I am trying to remember a design of conventional centre cockpit sliding canopy boat that would not go under Potter bridge. At the moment, I can't.

There used to be two types of enamel sign that were displayed on the dashboard of these boats :

(a)  "This boat must not be taken under Potter Heigham bridge without a pilot".

or (b) : "This boat will not normally pass under Potter Heigham bridge".

Wroxham Bridge was never mentioned and did not require a pilot.

My "yardstick" is the good old Bounty bathtub, the Solar 37, as these were designed specifically to be "Potter Heigham Bridge shaped". A bit like a Broads version of Panamax.

So if they won't go under any more, something must have changed, and it is not the boats!

 

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55 minutes ago, Vaughan said:

I am trying to remember a design of conventional centre cockpit sliding canopy boat that would not go under Potter bridge. At the moment, I can't.

There used to be two types of enamel sign that were displayed on the dashboard of these boats :

(a)  "This boat must not be taken under Potter Heigham bridge without a pilot".

or (b) : "This boat will not normally pass under Potter Heigham bridge".

Wroxham Bridge was never mentioned and did not require a pilot.

My "yardstick" is the good old Bounty bathtub, the Solar 37, as these were designed specifically to be "Potter Heigham Bridge shaped". A bit like a Broads version of Panamax.

So if they won't go under any more, something must have changed, and it is not the boats!

 

It's getting harder and harder to get under Wroxham... I've hired several centre-cockpit boats in recent years which used to go under Wroxham Bridge all day long and not been able to get them through.

The other big indicator I would say is that a fleet you're fairly familiar with used to be based just the other side of Wroxham bridge, and in the last ten years that became completely unviable as they were having to weigh the boats down with oil drums full of water on deck, open the seacocks and all sorts in order to get them back in to the yard. 

We all know that river levels have risen, the bridges may be sinking etc etc but it seems quite a large shift in just twenty years when those bridges have been around for hundreds of years and used to fit wherries through easily just as they did in the nineties.

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43 minutes ago, MauriceMynah said:

We hired Broadlander in 1968 and Ultima (in 69 I think) both had sliding cockpits. Fancy Free in 67 (cantilever cockpit cover) and Brinks Sandra, another slider. None of these would "Normally pass under Potter Heigham Bridge"

Trust you to find the exceptions that prove the rule!

Good old "Fancy" and "Carefree" had such a high foredeck that they would have hit the bridge before they got as far as the canopy! And Ultima was more like a US Coastgard cutter than a Broads cruiser!

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I have the log books for our boat which date back to the 1980s and  they regularly refer to her going under Wroxham bridge. Now, with an "all down" air draft of around 7ft 3 in and a beam of 10ft 6in, I don't think there are many days when she would go under. The fact that bridge pilots are mandatory now for hire boats going under Wroxham bridge certainly suggests that something has changed and I'm pretty sure that our boat hasn't grown bigger in the last few years.

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pilots are not needed for Martham boats for any bridge, for potter bridge you phone the yard and they send someone out, all the rest you are told the height you can get through (in my case 6 foot 2" for janet 3) - mind you they took her under potter with less than 6 foot on the marker.

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9 hours ago, MauriceMynah said:

 

I do have a question though, to those who remember the days of being able to moor at Marina Quays. When the lower Bure was thoroughly dredged, did the tide rip through there (from the Quays to Breydon) at the speed it does these days?

No it didnt

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43 minutes ago, JanetAnne said:

No it didnt

I would say it was more or less the same, especially at the Yacht Station.

This is no surprise, since if the river was deeper then, the volume of water being carried past was greater, so the speed of the current - over the ground - was perhaps a bit less.

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