The Bure Hump

[Mouldy]

In the EDP:

https://www.edp24.co.uk/news/24276382.broads-group-claim-bure-hump-making-norfolk-flooding-worse/

[batrabill]

Quote

One suggestion made by BRAG is that the mean low water level - the average height recorded - was miscalculated. 

This seems to be the core of the argument, and is easily checked.

 

[FairTmiddlin]

Environmental Agency spouting the same mantra they said about the Somerset levels " Dredging does not alleviate flooding"

When was the last time they flooded after the waterways were dredged?

[batrabill]

On 27/04/2024 at 11:46, FairTmiddlin said:

nvironmental Agency spouting the same mantra they said about the Somerset levels " Dredging does not alleviate flooding"

It’s absolutely true they are going to do more dredging in the Somerset levels. 
But they also plan to put in new pumping stations, and, build a tidal barrier at a cost of £220 million pounds. 
 

The idea that a bit more dredging in the Bure will end flooding is simply wrong. 

[Paladin]

I suggest comparing the situation in Somerset to the one in the Broads, is like comparing the Broads with the canals. Not comparable.

This is from a Guardian article written in response to the Somerset Levels floods:

“Among these problems, the Environment Agency points out, are:

1. Massive expense. Once you have started dredging, "it must be repeated after every extreme flood, as the river silts up again".”

Comment: The ONLY way the Broads is preserved for navigation is by dredging, as it silts up continually, regardless of instances of flooding.

“2. More dangerous rivers: "Removing river bank vegetation such as trees and shrubs decreases bank stability and increases erosion and siltation."

Comment: Removal of river bank vegetation such as trees and shrubs is part of the regular ‘maintenance’ the Broads Authority carries out.

“3. The destabilisation of bridges, weirs, culverts and river walls, whose foundations are undermined by deepening the channel: "If the river channels are dredged and structures are not realigned, 'Pinch Points' at structures would occur. This would increase the risk of flooding at the structure." That means more expense and more danger.”

Comment: Yet the new bridge at Great Yarmouth doesn’t have a detrimental effect on the river levels inland? Really?

“4. Destruction of the natural world: "Removing gravel from river beds by dredging leads to the loss of spawning grounds for fish, and can cause loss of some species. Removing river bank soils disturbs the habitat of river bank fauna such as otters and water voles."

Comment: The Broads Authority dredging removes the build-up of silt, but doesn’t remove river bed material, therefore doesn’t increase the basic depth of the river.

[MauriceMynah]

Thank you once again Paladin for yet another insightful post. There is a habit for people to take excerpts of posts and quote them out of context. I hope that doesn't happen to the above. 

I'm keeping my head down for the moment, but I'm simmering just below the parapet.  

[Vaughan]

33 minutes ago, Paladin said:

Comment: The Broads Authority dredging removes the build-up of silt, but doesn’t remove river bed material, therefore doesn’t increase the basic depth of the river.

Hence the continued existence of the hard gravel bottom on the old cattle swim at Stokesby, which has been there since the retreat of the last ice age.

My only comment on the EDP article would be that, in my opinion, the Bure hump is further upstream, starting at Scaregap Farm and going round the next 3 bends towards Stracey.

By the way, it is worth also reading the comments which are attached to the EDP article.

[grendel]

I agree Vaughan, it's pretty near the whole way from stokesby down that's shallow. The ba say that water depths have remained constant, but they don't account for the fact water levels have risen, so if the depth is the same, but the water is a foot higher, that means the bottom is a foot higher too, if the bottom is higher then there is more damming effect upstream, if I can see this how on earth have all their experts missed it?

[BroadAmbition]

At the recent Hickling meeting Packman stated that the lower Bure was well maintained 

Griff

[catcouk]

1 hour ago, grendel said:

... if I can see this how on earth have all their experts missed it?

Not that I wish to be called a conspiracy theorist (hang on, just putting my tin foil hat back on), but are the experts not paid to find the answers that their employers want? Also, isn't there a quote about, "lies, damned lies, and statistics"?

[BroadAmbition]

 if I can see this how on earth have all their experts missed it?

They haven't, its a big inconvenient truth that they are doing a fine job of ignoring

Griff

[JanetAnne]

Are water depts measured at the middle of the river or across its whole width?

[grendel]

They only measure the deep spots

[Tobster]

7 hours ago, JanetAnne said:

Are water depts measured at the middle of the river or across its whole width?

Aren’t they supposed to measure a mean low tide, to give the lowest value?

[Mouldy]

13 minutes ago, Tobster said:

Aren’t they supposed to measure a mean low tide, to give the lowest value?

What they’re supposed to do and actually do do appear to be two completely different things!

[grendel]

The issue still remains that they measure from a water level, if the water levels rise, and the depth remains the same, then effectively the bottom has risen too, the effect this has is the water gradient is reduced ( basically that's the drop in water level as you get nearer the sea) if the bottom rises enough that there is no gradient, then the rivers can't flow, so if the bottom has risen at the bure hump ( no matter the depth) then it's acting like a dam and causing raised water levels upstream, the water still has to escape so the depth of water may stay the same, but the flow gradient  has reduced, they not only need to relate the level to mean low water, but also to a fixed point on land to ensure that the river gradient is not being reduced too.

[BroadAmbition]

They only measure the deep spots

Is there any left?

Griff

[Vaughan]

1 hour ago, grendel said:

the effect this has is the water gradient is reduced ( basically that's the drop in water level as you get nearer the sea)

And in the recent meeting at Potter, they noted that the fall in the ground between the upper Thurne and Yarmouth Haven is only about 1 metre.

So if the Bure is now even one foot shallower, that has taken a full third off the gradient.

[MauriceMynah]

Some time ago and not necessarily on this forum, this subject was raised and there was an interesting exchange.  As I recall it went a bit like... 

" We need dredging done so we can get under PHB."

"No, our experts tell us that dredging won't affect flooding in that area."

... The point is that although one observation was made, the reply was to a completely different issue. 

I find it rather amusing that not only does the answer no longer holds true, it is downright wrong.

[Poppy]

20 hours ago, Tobster said:

Aren’t they supposed to measure a mean low tide, to give the lowest value?

By international agreement Chart Datum is defined as a level so low that the tide will not frequently fall below it. In the United Kingdom, this level is normally approximately the level of Lowest Astronomical Tide.

What datum the BA use is anybody's guess !

[floydraser]

5 hours ago, MauriceMynah said:

... The point is that although one observation was made, the reply was to a completely different issue. 

Those of us who have been married for a long time have learned to never point that out. 

[Mouldy]

4 hours ago, Poppy said:

 . . . . . . . What datum the BA use is anybody's guess !

Whichever fits their operating criteria the best, would be my guess!

[BroadAmbition]

Those of us who have been married for a long time have learned to never point that out.  

Only earlier this evening I found mysen in hot water with Commander-in-chief-Home

She mentioned that she would like to be a silent partner in a business earning a fat yearly wage

All I said was - You could never be silent as long as you have a hole in your derrière

I've since scarpered out of t lounge and sought refuge here in t office

Griff