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Flooding


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14 hours ago, Alway Swilby said:

Two days ago (Thursday) I was chatting to an EA chap who was having a look around at Isis Lock. The pound above the lock was quite high (as shown in the Oxford correspondant's first photo) and the weirs were flowing strongly. EA chap said the most of the extra water in the canal pound had come from drainage from the Oxford area. I should have asked him about Dukes Cut and whether that was feeding into the canal but I didn't. Later that day I noticed that the paddles were up at both ends of Isis Lock, presumably on purpose. At about midnight that evening the pound was about four inches below it's normal everyday level. Seeing as how I was moored on that pound and I didn't fancy coming to rest on the bottom I went down to the lock and closed the top paddle. The weirs wern't flowing at all. The pound recovered overnight to its normal level and the weirs were flowing as normal. Today (Saturday) the paddles are both up again but this time the pound is retaining it's level. The drop at Isis lock is just about six inches or so at the moment.

I wouldn't have thought they need to open the paddles at Isis lock to manage water as there are big overflow weirs on that pound? Also I think those photos are Osney lock on the river?

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6 minutes ago, Dave123 said:

I wouldn't have thought they need to open the paddles at Isis lock to manage water as there are big overflow weirs on that pound? Also I think those photos are Osney lock on the river?

As it says, one photo is of the pontoon below Isis lock on the canal; and one of the lock moorings below Osney lock.  CRT signs in the former,  and EA bollards in the latter. 

Edited by Scholar Gypsy
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15 hours ago, Alan de Enfield said:

 

That's high !

It's recently been a little higher than in the picture.

In  past years significantly higher still.

Its  the long term duration of the flooding that seems unusual this time .

 

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8 minutes ago, Alan de Enfield said:

Kings marina is about 6' above 'normal' with the walkway-ramp almost horizontal.

Probably 5ft at Farndon.

The water level did reach the top of the slipway and started to flood the yard. Its left behind a rather large puddle.

Water levels slowly falling now.

 

20191123.jpg

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We have just had a trip to the Lincolnshire coast with Syd for his birthday. We can't remember a time we have seen the ground quite so sodden and all of the ditches and watercourses so full.

 

There is still plenty of water to head into the rivers.

 

The Trent was on the verge of shutting Dunham Bridge creeping across the field and to the low point where it floods the road. The Fossdyke was also high.

 

It needs to stop raining!

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37 minutes ago, Graham Davis said:

I was at a classic car meet at  Montford Bridge, just upstream of Shrewsbury, this morning and the Severn is still well above normal levels. Locals are saying it is going down much slower than normal.

Same in the Trent.

The fields around here have standing water on them and the ground will be at 100% of its capacity to hold water. This will take a while to drain back into the river and can only start to do so as the river level starts to fall.

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1 minute ago, matty40s said:

Stopped at Gunthorpe briefly after a soggy wet day segwaying and go apeing in Sherwood Forest. Never seen the Trent flowing at this speed....

Flooding like that was an annual Winter event at Gunthorpe (we used to live a coupe of miles down the road) but improved flood control means that over the last 20+ years it has become a less frequent event.

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3 hours ago, matty40s said:

 Never seen the Trent flowing at this speed....

 

You might not have seen it but the water level has been higher than it is today.  So it must have flowed at that speed on previous occasions.

However I do agree the present speed and energy of the river is formidable.

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14 hours ago, Scholar Gypsy said:

As it says, one photo is of the pontoon below Isis lock on the canal; and one of the lock moorings below Osney lock.  CRT signs in the former,  and EA bollards in the latter. 

Ah yes my mistake...was looking at them in the wrong order! Still surprised they would have needed to open the paddles on Isis lock rather than rely on the weirs?

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1 hour ago, Dave123 said:

Ah yes my mistake...was looking at them in the wrong order! Still surprised they would have needed to open the paddles on Isis lock rather than rely on the weirs?

The weirs were going full pelt and still the canal was overflowing the top gate of Isis lock. 

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13 hours ago, MartynG said:

You might not have seen it but the water level has been higher than it is today.  So it must have flowed at that speed on previous occasions.

However I do agree the present speed and energy of the river is formidable.

As I understand it, speed and level are not exactly correlated

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1 minute ago, Mike Todd said:

As I understand it, speed and level are not exactly correlated

On the non tidal river they are related.

Otherwise at a given water level what do you think makes the river flow faster or slower?

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I am not an expert:

 

Firstly, quite a bit of the discussion has been about tidal, or semi tidal, rivers. As I have found out the hard way, level and speed on tidal waters are very complex and even long serving lock keepers can get their advice wrong at times.

 

Secondly, two significant factors: what profile the channel has at any given point. For example, if a river section has a flood plain area outside the normal channel but with a flood bank further away, then I suspect the rate will drop quite dramatically once the level reaches that point. It will certainly vary across the width of the river. Also, a lot will depend on what is happening up and down stream. Is the water backing up against higher levels further down?

 

What I have learnt in recent times is to have a lot of respect for water management professionals who are developing quite sophisticated models that help to predict what will happen in the short term and what also is the best (often a compromise) action to alleviate damage with the tools currently available. What is clear is that many amateur views, perhaps based on rather dated techniques, lead to loudly stated criticisms that have limited real substance.

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6 minutes ago, Mike Todd said:

 

 

...  two significant factors: what profile the channel has at any given point. For example, if a river section has a flood plain area outside the normal channel but with a flood bank further away, then I suspect the rate will drop quite dramatically once the level reaches that point. It will certainly vary across the width of the river. Also, a lot will depend on what is happening up and down stream. Is the water backing up against higher levels further down?

 

 

You are quite correct the speed of flow is affected by the shape of the channel and is in general greater in the middle than at the edges  That's because of friction between the water and the river bed and the bank sides .

 

What has been implied is the speed at the given depth it was at in the video clip was faster than it might have been on another day . Given the same water level at any particular place the same speed profile across the channel  will  always  be observed (in a non tidal section river and given no other man made influences ) .

 

I hope that's clear but its not easy to explain in a few words .

 

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These photos are of Torksey Lock today

 

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Courtesy of Suart Kinch on the Torksey group on Facebook.

 

The area is on amber alert for flooding and it has been said it was worse in 2000 and in 2007. (but it receded faster in those years)

 

It would seem that somebody decided this was a good time of year to replace the pumps at the " Trent Valley Internal drainage board at Torksey" ... obviously they were unlikely to be required in November.... sigh

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On 18/11/2019 at 15:43, cheshire~rose said:

These photos are of Torksey Lock today

 

74278429_10216189619518282_2188182848291

 

 

 

 

 

Impressive pictures.

Is that a ship on the pontoon?

On 18/11/2019 at 18:28, MHS said:

 in a few weeks time. 

30th November ?

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16 hours ago, MartynG said:

Impressive pictures.

Is that a ship on the pontoon?

30th November ?

It is a crane barge. Looks to be of dutch origins with the beautiful shape of the stern which I have managed to not get a picture of.

 

It has been there for a long while now.

 

20191027-095318.jpg

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1 hour ago, Naughty Cal said:

It is a crane barge. 

 

Now you mention it there were some temporary signs on the pontoon when we were there in mid September.  But no barge present at that time.

Edited by MartynG
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