Topic: Saline barrier _ trend or coincidence


ruby    -- Jan-4-2022 @ 9:06 PM
  Just noticed HW saline barrier is being closed again, probably for 36 hours.

My memory tells me it has closed far more frequently this winter than either last year or the year before.

Is this more evidence of increasing salt water incursion or is it my faulty memory making two and two add up to five .

Graham


Paladine    -- Jan-4-2022 @ 10:10 PM
 
I can't answer your question, ruby, but it has raised another one in my mind. What criteria are used when the decision to raise the barrier is made?

Are salinity tests carried out or is it simply done when particular tide and weather conditions occur?

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Bernard    -- Jan-4-2022 @ 10:46 PM
  My understanding is there are sensors along the river, pretty sure one is at Acle that flag up that it may need raising, knowledge of tides etc come in to play as well.


steve    -- Jan-5-2022 @ 5:39 AM
  Wether this helps or not but down here in the south east the Thames barrier has been raised a few times recently due to spring tides yesterday it was raised again , with it over lapping onto the banks at gravesend and onwards , sure it mentioned it would again today ,

steve and vicky
( not a broads local,so my views ,knowledge doesn't count )


ruby    -- Jan-5-2022 @ 7:56 AM
  I don't know paladine but this is the message from the EA that comes with the e mail.

Due to the continuing north westerly winds causing tide locking, we are expecting to see increasing salt levels in the River Thurne over the next few days.

Graham



Paladine    -- Jan-5-2022 @ 9:10 AM
 
Thank you for the replies. It rather seems to be a mixture of  meteorology and chemistry - weather prediction followed by water analysis.

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Dilligaf    -- Jan-5-2022 @ 10:02 AM
  The following link is a thread from another forum (no not that one) and I think you will see from the photos posted yesterdays tide was particularly high due to the weather conditions.
Wind speed and direction is one of the main causes.
https://forums.ybw.com/index.php?threads/big-tide-at-the-tide-mill.577263/#post-7877948

Dave.
Formerly 'LeoMagill'


expilot    -- Jan-5-2022 @ 12:01 PM
  And today's tide here at Potter is even higher than yesterday's with another three hours yet to flood. The Thurne is overtopping the flood defences in the usual places and, doubtless, the IDB pumps will be pumping it from the marshes back into the flooding river!

"There are old pilots.  There
are bold pilots............."


Paladine    -- Jan-5-2022 @ 12:12 PM
 
The output of some of these pumps can be quite ferocious. Perhaps the outfall pipes could be fitted with mini hydro-electric thingies, to offset the cost of the electricity they use.


Been hit by another boat? Report the incident to the Marine Accident Investigation Branch’s dedicated accident reporting line on 023 8023 2527 which is monitored 24 hours a day.  Help to make the Broads safer.


Hylander    -- Jan-5-2022 @ 1:53 PM
  Dilligaf ,   where is The Mill pictured please?   Not sure I can place it.

Women dont nag they just
point
things out...



M


Dilligaf    -- Jan-5-2022 @ 4:11 PM
  It's tidemill at woodbridge on the Deben, at normal low water it's mostly a sea of mud there with a trickle down the middle, the marina behind the mill has a cill to keep enough water in so boats can stay floating.

Dave.
Formerly 'LeoMagill'


MandA    -- Jan-5-2022 @ 6:56 PM
  I still do not understand how the barrier keeps the saline out as the water goes around the ends of the barrier and the water is always the same level each side of the barrier perhaps someone could enlighten me,we moor  in wood,s marina.
Adrian.

MandA


ruby    -- Jan-5-2022 @ 7:34 PM
  Hi Adrian

I also wonder how it works, noone I speak to seems to understand the science .

I do think it restricts some water though as the marina at our end never seems as high as the river itself with the barrier in place

The other thing I don't understand is where are all the fish resting  . I have placed fish  finders and cameras under our boat when the barrier is in place and always seen diddly squat , but they may of course be in another basin

Graham


Greybeard    -- Jan-5-2022 @ 7:45 PM
  Because fresh water is less salty and less dense than water from the ocean, it  floats on top of the heavier seawater.

my appearance is down to me, my attitude is down to you.


Bluebell    -- Jan-5-2022 @ 8:11 PM
  I also moor in HW basin, and have fished while the barrier is up without getting a bite - i assume the fish must have gone upriver under the bridge… Playful Wink

With kind regards

Jim

was  Bluebell now Chiltern Lady (an Aquafibre Opal built by Fineway Cruisers Hoveton)


ruby    -- Jan-5-2022 @ 8:23 PM
  Hi Jim

The barrier is only there because the EA say that many thousands ( my memory says at least 100k  but I cannot be sure of that )of fish shelter in the marina to keep away from the salt in the river. Without the barrier those that escaoe from the river into   the marina would eventually be overwhelmed by the salt.

I am intrigued  as I have never seen any evidence of many thousands of fish resting in the marina.

Graham


Paladine    -- Jan-5-2022 @ 8:49 PM
 
https://www.gov.uk/government/news/thousands-of-fish-saved-from-salt-water-during-tidal-surge

There was an EA-liveried van in the HW/Latham car this morning.

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ruby    -- Feb-4-2022 @ 11:41 AM
  A quick update the barrier was closed again last week and still hasn't re opened.
.
They are hoping for tomorrow    


This is not good news for the user's of the marina but even worse for the inhabitants of the thurne which have been trying to survive  salt water for over a week

Graham


Bluebell    -- Feb-4-2022 @ 2:05 PM
  I’ve been hoping to get out of the marina all week, but looks like it’ll be tomorrow at the earliest before the barrier goes down. Sod’s law is I’m then too busy on other stuff to be boating next week. Fingers crossed for the week after…

I wish I could be convinced the barrier is worthwhile, I don’t really understand how it works.

With kind regards

Jim

was  Bluebell now Chiltern Lady (an Aquafibre Opal built by Fineway Cruisers Hoveton)


Harrietbrandon    -- Feb-4-2022 @ 3:57 PM
  Herbert Woods usually start hiring out some of their own boats in February, just wondering how that would work?

HB


Bluebell    -- Feb-4-2022 @ 4:05 PM
  At the tail part of last season the boats waiting to come in and those ready to go out had the barrier lowered so they could move in and out…

With kind regards

Jim

was  Bluebell now Chiltern Lady (an Aquafibre Opal built by Fineway Cruisers Hoveton)


Harrietbrandon    -- Feb-4-2022 @ 4:22 PM
  Thank you. Just curious how it would work.

HB


MandA    -- Feb-4-2022 @ 6:57 PM
  I quite agree with Jim (Bluebell),I can’t understand how it works when the water creeps around the end of the barrier and is always the same level as the river .
We’ve moored at Herbert Woods for 15  plus years so are used to the situation I expect the office must point out the situation to new Moorers.
Adrian.

MandA


Bluebell    -- Feb-5-2022 @ 9:16 AM
  Just had an email from EA. The barrier will be lowered at 10.30 today to allow passage of boats in and out. You’ll have to be quick though, it’ll be raised again as soon the movements are complete. The EA are hoping to lower on Monday, but can’t be sure as their predictions are only for the next 36 hours…

My question is, if the barrier is lowered, even for a shortish time, won’t the salty water rush into the basin ?

With kind regards

Jim

was  Bluebell now Chiltern Lady (an Aquafibre Opal built by Fineway Cruisers Hoveton)


Marshman    -- Feb-5-2022 @ 10:29 AM
  Some will but as the basin is already full of water, not much!!

To satisfy those questioning it, perhaps they need to go out and check the salinity of the water either side of the barrier and at the same time check to see if it has any fish in it!!

At least they are trying to limit the impact of saline surges to avoid the death of many fish - even a modest degree of success is better than nothing!!!


annville    -- Feb-5-2022 @ 11:46 AM
  Hi As salt water floats on top of fresh water you only need the barrier at the top allowing fresh to flow in and out as tide rises and falls, a barrier at Yarmouth would make this one redundant. John


Marshman    -- Feb-5-2022 @ 12:28 PM
  And there was me thinking that the more dense water (salt) was heavier and as a result the freshwater was on the top!!


Steve51    -- Feb-5-2022 @ 12:29 PM
  John, I think you'll find it's the other way round. Fresh water being less dense and lighter, floats on top of salt water.

Steve. CM1 and NR12


annville    -- Feb-5-2022 @ 2:27 PM
  Thanks for that Steve. John


K123Vette    -- Feb-13-2022 @ 1:03 PM
  EA fisheries chap doing barrier last week mentioned that salt water is denser than fresh so will stay lower in the flow so lowering the barrier just a little should not increase salt in the basin. The current barrier is near the end of its serviceable life and does indeed let water flow round the sides. The EA are surveying the site and looking at options of the future. The saline barrier raised has also partially prevented some of the yard sheds and car park from flooding during the recent high waters.
  

K123Vette


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