Lethal Salt Surge

[marshman]

Good post!

I would reiterate a point I made earlier and that is that the EA's primary function in time of flooding, is to save human lives - fish procreate at an astonishing rate ,far far faster than humans.

It is NOT the end of the world and I doubt if next year will find fishing a lot different - when this high water level goes away, as it will, it will be interesting to see there are fish around. Would the boys with rods let us know?

My guess is that they will still be around - but don't blame the surge unless you were convinced its not your ability causing the problem. Most pictures I saw were of very small fish but I guess some of the bigger ones were affected too.

Pike are particularly susceptible to these incursions- they would be helped immeasurably if we saw a moratorium on pike fishing over the summer. How about that pike group getting on with that - even 10/15 years ago you hardly ever saw pike fishermen before the 1st October. Now pike floats are around every corner, often unattended, like a rash all summer! Now you are not telling me thats good for the pike population!!!

Yes the fishing will recover just as it did before and sometime, would someone either at the BA or EA let us know exactly how far this surge reached? As I said at least a decade or so ago, one reached Horning Water Works and no, I don't take a hand drawn map as definitive proof of the extent of this one!!

[grendel]

I do recall reading somewhere that a barrier at great Yarmouth would cause great problems on the northern side of the town, I think the issue was that the entire area sits on a gravel and sand spit, and if a barrier was erected, the sea water would find its way through that sub surface and erode the gravel and sand, causing issues such as subsidence  etc. also that the bure would then possibly change its course to the sea if enough erosion was caused.

so the answer is never as simple as you would think it should be.

[Vaughan]

Well done Paul and I agree with all your points, which are well put.  I too have noticed that there are far more marker buoys on the inside of bends on the lower Bure than there used to be.  The inside of a bend flows slower, so this is where an alluvial river will deposit its silt.  Interesting to see the hydrothingy survey of the Yare between the Haven Bridge and the Breydon Bridge.  See how the deep water under the Breydon Bridge is right at the outside of the bend in the channel.  See also the area of shallow water right across the channel upstream of the Bure junction.  I guess this will be because the tide turns on Breydon, an hour before it turns on the Bure.

The scheme for a flood barrier in the early 70s was turned down for more or less the same reasons that you give in your post.

9 hours ago, Paul said:

Or should we leave well alone and let nature take it's course?

Here we should remember that the Broads area is not natural.  It is all re-claimed land, drained and made usable by Dutch immigrants fleeing the Catholic persecution of the Huguenots in the 16th century.  That's why we have all those Dutch type wind pumps all over it.  In other words, it is Man-made and must be maintained by Man.  So if Man doesn't like what is happening to it, Man must make adjustments.  Or perhaps more accurately, correct some of his recent mistakes?

There are two important points in addition to those that you and Marshman have made :

1/. Depth of the Yare.

The whole of the Yare  used to be dredged to a minimum 12 feet at MLWS, for the sea going coaster traffic to the port of Norwich.  I doubt it is more than half that deep now.  A huge volume of water, that used to absorb the surge tides as they came up over Breydon.

The Principle of hydraulics (this is a "hydraulic" problem) is that you can't compress a fluid like water : a given volume of water in one place will be the same volume when you move it to another place.  You can't squeeze it and you can't stretch it.  So all those millions of gallons that used to be absorbed by the Yare have got to go somewhere else.  Up the Bure perhaps?   Or over the banks in Beccles?

2/. Washlands.

To make matters even worse, up until the early 70s - and for hundreds of years before - large areas of grazing meadow in the lower reaches of the Yare, Bure and especially the Waveney, had their river banks set at a height where they would deliberately be flooded by a surge tide.  They became enormous water retention basins which stopped the surge going further upriver.  Grazing land is not much affected by brackish water, so you could get the cattle back on the field a few days later.

This was fine until the farmers decided to try and make more money out of arable, rather than livestock farming.  Arable land will be ruined by brackish water for 3 or 4 years after a flood and you also need a lower water table in the field, to grow the crops.  So the farmers lobbied parliament to have the river banks built much higher, to allow "deep dyke" drainage of the fields.  Sure enough, now that the rivers were enclosed by the banks, the water had to go somewhere else!  Old Archimedes again!  So now we have to have flood banks in the towns and villages as well, where we never needed them before.  If the water is too high under Potter Bridge these days, I am not at all surprised!

I am not saying we should dredge the Yare to 12 ft again but now that the farmers have turned back to dairy and livestock and re-instated the grazing meadows, I see no reason why breaches cannot be made in the high banks to allow the use of washlands again.  A cheap and immediate solution.

 

Climate change.

Of course we have climate change : we always have done and always will do.  The planet Earth is an enormous lump of molten rock which, for millions of years, has been slowly cooling from the surface inwards. That's why we still have volcanoes, earthquakes and tectonic plates. Personally, I don't believe our puny efforts as humans are going to make any difference to that.  If it were not for climate change, the whole of Norfolk and Lincolnshire would still be under a glacier.  The same one that scoured out the low basin that we now call The Broads.

 

 

 

[Smoggy]

1 hour ago, Vaughan said:

The whole of the Yare  used to be dredged to a minimum 12 feet at MLWS, for the sea going coaster traffic to the port of Norwich.  I doubt it is more than half that deep now.  A huge volume of water, that used to absorb the surge tides as they came up over Breydon.

Sorry Vaughan but if the river was deeper at mlws it wouldn't absorb any more as the extra capacity would already be full before the tide came in, now if you could dredge the top instead of dredging the bottom.....

The washlands however would make a hell of a difference, the great ouse still has it's washes between the old and new bedford rivers and the surrounding areas (and upstream) would be in big trouble without.

[Vaughan]

9 minutes ago, Smoggy said:

Sorry Vaughan but if the river was deeper at mlws it wouldn't absorb any more as the extra capacity would already be full before the tide came in,

Ah, but would the salt water go as far up it?

Perhaps we can think of it this way : if you have a 10 litre saucepan with 5 litres in it, it is half full. If you pour another 5 litres in, it fills up.

If your bath is half full and you pour in the same 5 litres, it won't even go up an inch.

"Eureka!" as Archimedes was wont to say.

 

[Gracie]

1 hour ago, Vaughan said:

Well done Paul and I agree with all your points, which are well put.  I too have noticed that there are far more marker buoys on the inside of bends on the lower Bure than there used to be.  The inside of a bend flows slower, so this is where an alluvial river will deposit its silt.  Interesting to see the hydrothingy survey of the Yare between the Haven Bridge and the Breydon Bridge.  See how the deep water under the Breydon Bridge is right at the outside of the bend in the channel.  See also the area of shallow water right across the channel upstream of the Bure junction.  I guess this will be because the tide turns on Breydon, an hour before it turns on the Bure.

The scheme for a flood barrier in the early 70s was turned down for more or less the same reasons that you give in your post.

Here we should remember that the Broads area is not natural.  It is all re-claimed land, drained and made usable by Dutch immigrants fleeing the Catholic persecution of the Huguenots in the 16th century.  That's why we have all those Dutch type wind pumps all over it.  In other words, it is Man-made and must be maintained by Man.  So if Man doesn't like what is happening to it, Man must make adjustments.  Or perhaps more accurately, correct some of his recent mistakes?

There are two important points in addition to those that you and Marshman have made :

1/. Depth of the Yare.

The whole of the Yare  used to be dredged to a minimum 12 feet at MLWS, for the sea going coaster traffic to the port of Norwich.  I doubt it is more than half that deep now.  A huge volume of water, that used to absorb the surge tides as they came up over Breydon.

The Principle of hydraulics (this is a "hydraulic" problem) is that you can't compress a fluid like water : a given volume of water in one place will be the same volume when you move it to another place.  You can't squeeze it and you can't stretch it.  So all those millions of gallons that used to be absorbed by the Yare have got to go somewhere else.  Up the Bure perhaps?   Or over the banks in Beccles?

2/. Washlands.

To make matters even worse, up until the early 70s - and for hundreds of years before - large areas of grazing meadow in the lower reaches of the Yare, Bure and especially the Waveney, had their river banks set at a height where they would deliberately be flooded by a surge tide.  They became enormous water retention basins which stopped the surge going further upriver.  Grazing land is not much affected by brackish water, so you could get the cattle back on the field a few days later.

This was fine until the farmers decided to try and make more money out of arable, rather than livestock farming.  Arable land will be ruined by brackish water for 3 or 4 years after a flood and you also need a lower water table in the field, to grow the crops.  So the farmers lobbied parliament to have the river banks built much higher, to allow "deep dyke" drainage of the fields.  Sure enough, now that the rivers were enclosed by the banks, the water had to go somewhere else!  Old Archimedes again!  So now we have to have flood banks in the towns and villages as well, where we never needed them before.  If the water is too high under Potter Bridge these days, I am not at all surprised!

I am not saying we should dredge the Yare to 12 ft again but now that the farmers have turned back to dairy and livestock and re-instated the grazing meadows, I see no reason why breaches cannot be made in the high banks to allow the use of washlands again.  A cheap and immediate solution.

 

Climate change.

Of course we have climate change : we always have done and always will do.  The planet Earth is an enormous lump of molten rock which, for millions of years, has been slowly cooling from the surface inwards. That's why we still have volcanoes, earthquakes and tectonic plates. Personally, I don't believe our puny efforts as humans are going to make any difference to that.  If it were not for climate change, the whole of Norfolk and Lincolnshire would still be under a glacier.  The same one that scoured out the low basin that we now call The Broads.

 

 

 

Wow! I don't get involved in these matters, purely because of it all going way over my head but this post gives me a much better understanding

Thank you Vaughan 

[Smoggy]

19 minutes ago, Vaughan said:

Ah, but would the salt water go as far up it?

Perhaps we can think of it this way : if you have a 10 litre saucepan with 5 litres in it, it is half full. If you pour another 5 litres in, it fills up.

If your bath is half full and you pour in the same 5 litres, it won't even go up an inch.

"Eureka!" as Archimedes was wont to say.

 

Surely that would only apply if they dug it wider rather than dredging it deeper, that said with the extra capacity the salt levels (%) would be lower even if the water makes the same distance up river, assuming it mixes and the salt doesn't run under the fresh being heavier and colder.

[Vaughan]

1 minute ago, Smoggy said:

if the water makes the same distance up river, assuming it mixes and the salt doesn't run under the fresh being heavier and colder.

Also, sailors in the Yare Navigation Race will confirm that the ebb on the Yare is very much stronger than the flood.  This is because it is fed by the headwaters of the both the Yare and the Wensum.  Both these rivers go right over into west Norfolk, not all that far from Kings Lynn.

[Bikertov]

I recall reading in the papers a few weeks ago how low the River Rhine is, down to only a few centimetres in some points, and how it is stopping commercial river traffic from navigating.

https://news.sky.com/story/europe-drought-images-show-extremely-low-water-levels-along-rhine-river-as-officials-warn-transport-of-goods-could-be-affected-12669978

 

[grendel]

45 minutes ago, Bikertov said:

I recall reading in the papers a few weeks ago how low the River Rhine is, down to only a few centimetres in some points, and how it is stopping commercial river traffic from navigating.

https://news.sky.com/story/europe-drought-images-show-extremely-low-water-levels-along-rhine-river-as-officials-warn-transport-of-goods-could-be-affected-12669978

 

i think the logistics of moving the salt surge to the rhine might defeat us., you would need big pumps and a lot of hose.

[Bikertov]

16 hours ago, grendel said:

i think the logistics of moving the salt surge to the rhine might defeat us., you would need big pumps and a lot of hose.

Ooops - I deserved that for hijacking the thread from a salt surge to low water levels 

[andyg]

20 hours ago, grendel said:

i think the logistics of moving the salt surge to the rhine might defeat us., you would need big pumps and a lot of hose.

And just prey the Russian don't mistake said long hose as a gas pipeline..doh...

[TheQ]

In the Late 1200s John Oxnead a Brother of St Benets Abbey recorded floods and seas breaking through to the broads.. devastating properties and land across the broads and marshes.

In 1608 the sea broke through at Eccles floods and salt water  reached Stalham, Coltishall, Norwich and St Olaves..

Today we have better sea defences.. So the sea has to come up the rivers, hence salt surges

[Smoggy]

On 30/09/2022 at 14:40, andyg said:

And just prey the Russian don't mistake said long hose as a gas pipeline..doh...

That would be a disaster, imagine all that salt water leaking into the sea!

[rightsaidfred]

23 minutes ago, TheQ said:

In the Late 1200s John Oxnead a Brother of St Benets Abbey recorded floods and seas breaking through to the broads.. devastating properties and land across the broads and marshes.

In 1608 the sea broke through at Eccles floods and salt water  reached Stalham, Coltishall, Norwich and St Olaves..

Today we have better sea defences.. So the sea has to come up the rivers, hence salt surges

Once again we have man trying to control nature instead of working with it, Happisburgh once an inland community is just one example of the natural changes of climate change and evolution over centuries, the biggest single issue with the current situation is in trying to contain water levels within man made boundaries instead of allowing it to flow out onto the historical flood plains and I am afraid any sort of barrier at GY will only exasperate problems elsewhere rather than relieve what is a natural event, if we want to do anything we should give nature back what we have taken ie the salt marshes and flood plains on the lower rivers.

Fred

[Vaughan]

On 27/09/2022 at 05:34, ChrisB said:

I am posting this here (took me a while to find it!) in support of Griff's new thread called "Dredging lower Bure", where the author says they have heard of a sand bar across Breydon but have not seen it.

Well, here it is, in bright green and yellow!

We can see how the deep part of the river going under the Breydon Bridge is to the north, on the outside of the bend in the channel.  This is just as you would expect in an alluvial river.

There is also a pronounced sand bar right across the channel just above the Bure junction.  This, to me, is quite clearly caused by the fact that the tide turns on Breydon an hour before it turns on the Bure.  So the last of the ebb coming down through GYYS is diverted up the Yare by the incoming tide and drops its alluvial silt as it slows down.

So we have a "Yare hump" as well as a Bure hump!