Lethal Salt Surge

[Bernard]

I see elsewhere they are closing the barrier at Herbert Woods later today due to another salt surge.

[BroadAmbition]

Half an hour past high tide. Still racing in. River level with quay heading now. Constantly adjusting fenders and lines. 5ft3”” under Vauxhall bridge

The Bure hump has a lot to answer for as it restricts the ebb which makes the next flood push higher up. We’ve been warning  about this scenario for years now 

Griff

[ChrisB]

From the BA's Hydrographic Survey, I am struggling to find this " Hump " can anyone identify it?

 

[ChrisB]

It was the Autumnal Equinox last Friday so some of the years highest of tides are only to be expected. With river fresh water levels low and still warm the denser saline, colder water will travel further up stream below the fresh.

With rising sea levels, I think we are seeing an environmental adjustment to what is after all an Estuarine Environment that is tidal for a long up stream.

It is not just The Broadland Rivers, I am told salinity is rising in the freshwater pools along the coast road around Cley and Salthouse.

[Hylander]

On 24/09/2022 at 11:24, rightsaidfred said:

Yes sadly this will go way beyond just a fish kill as bad as that is, it will kill of invertebrates and insect forms which are the bottom of the food chain that provide the food for many birds including swifts and swallows as well as fish, lack of fish will affect Herons, Kingfishers etc. Coots and some duck species will suffer from the lack of molluscs, Otters will turn even more to water birds as a food source and so the food chain goes on, mammals will suffer from tainted drinking water and some plant life will suffer, I will leave it to some with more ecological knowledge than myself to expand on this.

Fred

I will amend my post asking about Otters and reading through I found this post which answers that question.

 

[ChrisB]

Salt or fresh makes no difference to Otters, prior to living in Norfolk all the Otters I had ever seen were coastal in Devon and the Western Isles.

[Smoggy]

30 minutes ago, ChrisB said:

Salt or fresh makes no difference to Otters, prior to living in Norfolk all the Otters I had ever seen were coastal in Devon and the Western Isles.

Lack of fish does though.

 

[CeePee1952]

Just seen on HW's webcam that they have the salt water surge barrier down.

Chris

[Mouldy]

I’m no expert in these fishy things.  I have a very cheap rod and reel and do occasionally drown a piece of bread flake or sweetcorn (depends what I can sneak from the cupboard, without ‘er indoors complaining).  It’s certainly not enough to qualify as a hobby, just something to pass a bit of time sometimes. The following questions are therefore not being asked by a serious angler, whose sport will have been affected by this event.

The tidal surge that occurred about ten days ago clearly pushed further up the rivers than any previous event, or certainly in most peoples recent memories.  There’s been a considerable amount of noise on social media, including comments on here, regarding why the barrier at Woods wasn’t raised.

Now don’t get me wrong, I realise that closing the barrier would have saved some fish, but given how far the salt water pushed up through the rivers, including The Yare, The Bure, The Thurne and a long way up The Ant, the number saved would surely have been small by comparison to the numbers lost elsewhere.  Why is there only a barrier at Woods?  Do the fish taste salty water and think ‘I know, I’m off to Potter because it’s safe there?’

Why are there not barriers at say Acle Dyke, Upton Dyke, Oby, Womack Dyke, Hardley Dyke, Langley Dyke and more, to provide more places of refuge for such events?

The other thing that occurs to me is the question of commerce over the environment.  Closing the barrier at Woods over the weekend of 16th - 19th September would have created a huge problem for returning craft and new hirers at the boatyard.  Had it been closed, how would they have been able to accommodate a fairly busy turnaround weekend and was this a factor in the EA’s decision not to close the barrier.  If it was, why is the barrier there?  Could a barrier be erected at Potter bridge, so as not to affect the business of the boatyard?

To some, these may seem stupid questions.  Forgive me, I’m not an expert in these matters so ask for sensible answers.

 

[CeePee1952]

27 minutes ago, CeePee1952 said:

Just seen on HW's webcam that they have the salt water surge barrier down.

Chris

Ooops! I meant "up"! 

Chris

 

[rightsaidfred]

6 minutes ago, Mouldy said:

I’m no expert in these fishy things.  I have a very cheap rod and reel and do occasionally drown a piece of bread flake or sweetcorn (depends what I can sneak from the cupboard, without ‘er indoors complaining).  It’s certainly not enough to qualify as a hobby, just something to pass a bit of time sometimes. The following questions are therefore not being asked by a serious angler, whose sport will have been affected by this event.

The tidal surge that occurred about ten days ago clearly pushed further up the rivers than any previous event, or certainly in most peoples recent memories.  There’s been a considerable amount of noise on social media, including comments on here, regarding why the barrier at Woods wasn’t raised.

Now don’t get me wrong, I realise that closing the barrier would have saved some fish, but given how far the salt water pushed up through the rivers, including The Yare, The Bure, The Thurne and a long way up The Ant, the number saved would surely have been small by comparison to the numbers lost elsewhere.  Why is there only a barrier at Woods?  Do the fish taste salty water and think ‘I know, I’m off to Potter because it’s safe there?’

Why are there not barriers at say Acle Dyke, Upton Dyke, Oby, Womack Dyke, Hardley Dyke, Langley Dyke and more, to provide more places of refuge for such events?

The other thing that occurs to me is the question of commerce over the environment.  Closing the barrier at Woods over the weekend of 16th - 19th September would have created a huge problem for returning craft and new hirers at the boatyard.  Had it been closed, how would they have been able to accommodate a fairly busy turnaround weekend and was this a factor in the EA’s decision not to close the barrier.  If it was, why is the barrier there?  Could a barrier be erected at Potter bridge, so as not to affect the business of the boatyard?

To some, these may seem stupid questions.  Forgive me, I’m not an expert in these matters so ask for sensible answers.

 

Not stupid questions at all and you are right in a lot of what you say, the problem with salt surges is largely down to the strength and direction of winds in the North Sea and in particular when combined with certain tidal conditions, others will be able to explain this better than myself, your suggestion about barriers in other locations is well worthy of consideration although not necessarily a strait forward one but it should be feasible on some of the smaller dykes around Womack, Horning, South Walsham etc but has probably not been considered because of the concentration on calling for a barrier of some description at GY.

As for why the barrier wasn`t raised I don`t know as normally HW are given prior notice and move boats out onto the river beforehand as was the case yesterday but as you say that only protects one small area in the great scheme of things.

Fred

[Tobster]

4 hours ago, ChrisB said:

From the BA's Hydrographic Survey, I am struggling to find this " Hump " can anyone identify it?

 

Is the Bure loop not page 2

[Smoggy]

Surely a "hump" would slow the drainage of fresh and the increased water level would hold back some of the saline, although incoming sea water often runs under the fresh giving the same body of water different directions of flow at different levels, at the lower ends of the rivers at least.

[SteveO]

Sadly, I think that with East Anglia sinking and sea levels rising, all we can do is slow the the inevitable and enjoy what we've got while we've got it. It seems likely that, ultimately, nature will do Packman's work for him and the whole place will become salt marsh, fit only for a bird sanctuary.

 

[marshman]

Smoggy is of course exactly right and for all those who advocate its removal, even if it exists, have absolutely no idea of the impact in overall terms.

 Weather conditions play a major part on the tides in Broadland but what is unquestionable, is that the surges continue to move upstream further if you look at them from an overall basis.  This seems a difficult one to make a real judgement on as different surges affect some areas more than others at different times - I have seen bad ones north of Potter but this time that didn't seem to happen.

What did happen is because of the activities of the BAG (Broadland Angling Group ) this got huge publicity  - to me it seemed no better or worse than other surges and unaffected fish will quickly move into those affected areas.  The effect of previous surges have not had serious impact on fishing generally and the rivers will recover quickly.

However we have to live with the consequences of rising water levels, enough now to be noticeable, and this is just another one - overall I suspect it will not be any worse than previous ones and there are plenty else we can do! How about a pike fishing moratorium, to start with except for perhaps designated periods - everyone fishes for pike  now virtually all year round. It never used to be like that!

 

[grendel]

2 hours ago, Mouldy said:

Why are there not barriers at say Acle Dyke, Upton Dyke, Oby, Womack Dyke, Hardley Dyke, Langley Dyke and more, to provide more places of refuge for such events?

I would surmise, that barriers cost a lot of money, as do the staff required to go round and shut them all and reopen them as necessary.

I wonder if anyone knows how and when the barriers at Herbert Woods came about, and who did the work?

[grendel]

just wonderiing- what with the hoveton great broad debate over the fish barriers, is that another place where the fish would take refuge during a salt surge, if so this would be another reason against fish barriers at that location.

[marshman]

I think it was the EA originally Grendel, but I could be wrong!!

One thing you all have to remember is the EA's primary function during flooding is to save lives and not fish. As I said earlier I really doubt the long term effects of this surge will have been worse than others  - for example neither Hickling nor West Somerton seem to have been affected, both areas are hotspots for previous surges.

Not underplaying it but fish stocks following previous surges, usually replenish fairly quickly so I doubt all is lost!

[Mouldy]

11 minutes ago, grendel said:

I would surmise, that barriers cost a lot of money, as do the staff required to go round and shut them all and reopen them as necessary.

I wonder if anyone knows how and when the barriers at Herbert Woods came about, and who did the work?

I get that, but this situation has become a major issue to many and so many questions asked about why the barrier wasn’t closed at Woods.  In reality, the number of fish saved would have been a very small percentage of those that have perished.

Everything always boils down to money. I have no idea how many Woods boats were turned around over the weekend of 16th - 19th September, but I have to say that there appeared to be a large number of Woods craft on the rivers over that weekend.  I do wonder if the decision to not close the barrier was due to the logistical nightmare that would have ensued if it had been closed.  There is no way that they could all have been turned round on the river with no fuel and pump out services available riverside.

[webntweb]

10 hours ago, BroadAmbition said:

Half an hour past high tide. Still racing in. River level with quay heading now. Constantly adjusting fenders and lines. 5ft3”” under Vauxhall bridge

The Bure hump has a lot to answer for as it restricts the ebb which makes the next flood push higher up. We’ve been warning  about this scenario for years now 

Griff

In which reach is the hump, or does it move over time with river flow/tides?

[marshman]

Griff - as I pointed out the EA's primary responsibility is to save human life and prevent flooding, not save fish which, as before, replenish naturally. It is for this reason that they have spent lots of money in GY raising the harbour walls.

I know that for years you have been concerned with the "Bure Hump" if there actually is such a thing which I can neither confirm or deny, but like others probably believe there is no one simple solution - everyone should always beware of the Law of Unintended Consequences! This time the surge has occurred during a period of strong north westerlies over a period when tides are naturally very high - flooding could have been much worse elsewhere. Overtopping at GY could have had disastrous results to the low lying areas in that Borough.

[rightsaidfred]

2 hours ago, grendel said:

I would surmise, that barriers cost a lot of money, as do the staff required to go round and shut them all and reopen them as necessary.

I wonder if anyone knows how and when the barriers at Herbert Woods came about, and who did the work?

I think it was around 25 years ago but could be wrong, while the current situation is very distressing it should be remembered that while most surges don't get to the levels of the current one there was one in 2006 that was very similar in many ways including warmer than normal water temperatures encouraging fish to stay further downstream, memory's not what it was but I seem to remember something similar in the early 1990s as well and the system recovered from both, while I am all for improvement in any aspect of life once again we are getting into the realms of man verses nature.

Fred     

[Meantime]

7 hours ago, Mouldy said:

 Why is there only a barrier at Woods?  Do the fish taste salty water and think ‘I know, I’m off to Potter because it’s safe there?’

 

4 hours ago, grendel said:

I wonder if anyone knows how and when the barriers at Herbert Woods came about, and who did the work?

I believe that the barrier at Herbert Woods has two purposes. When a salt surge event occurs normally the fish swim upriver to get away from the incoming salt. As the HW basin is a large dead end pool of water off the main river the fish can tend to swim into there in large numbers and become trapped and eventually lack of oxygen becomes an issue. So I believe the first purpose is to encourage fish to swim past and further up river to escape the salt surge, and secondly to protect any fish already in the basin before the salt surge occurred. 

[Meantime]

10 hours ago, ChrisB said:

From the BA's Hydrographic Survey, I am struggling to find this " Hump " can anyone identify it?

I'm not sure how out of date the BA survey is, but in any case if you travel along that section you will find a couple of places marked with temporary yellow sticks marking shallow areas on bends. These presumably don't suddenly drop to very deep water but must be a gradual incline towards the centre of the channel.

In addition it is noticeable the lack of current flow on the Lower Bure. 20 years ago if going towards Yarmouth with the ebb and taking it easy with the revs it was normal to feel the stern of the boat being taken on the bends due to the current to the point that you needed to increase the revs to maintain steerage. That never happens these days.

[grendel]

when i was coming downstream earlier this year i did encounter a shallow section, i was a good 12 foot from the bank, and suddenly slowed, I got off again and carried on round the  corner where there were yellow posts about 10 feet off the bank, so there are some shallow spots along that lower section.