There's a lot of nonsense being spoken about a 1-in-100 year event, with many people thinking that the event won't recur in the next hundred years. In fact it means that that the chance of it occurring again next year is 1 in 100 (and that's based on past data, without any allowance for changing climate)

Now for the heavy stuff.

The chance of a 1-in-100 year event occurring after exactly N years is 0.99 ^ (N-1) * 0.01. To find out if the event will happen again within an N-year period, you have to add up the chance of it happening after 1 year, after 2 years, after 3 years ...after N years. Fortunately we have spreadsheets to do the heavy lifting!

Floods of this seriousness are variously stated to have occurred 6 years ago and 10 years ago. My spreadsheet tells me that:

The chance of a recurrence within 6 years (i.e could happen in any year from year 1 to year 6) is 5.8%

The chance of a recurrence within 10 years is 9.6%

(So not that improbable - you could have got better odds on Bournemouth beating Chelsea!)

Perhaps more surprisingly, the chance of a recurrence within 100 years is only 63.4 % i.e. there's no certainty that the 100-year flood will recur within that time anyway.

 

It was good to hear the 'More or Less' programme team putting the facts straight on Radio 4 this evening.

 

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Awesome! That's about the only bit of the storm I would have loved to see.

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Goodness me.  Thank you for posting the photos Bagfish and I'm so glad you managed to keep your feet dry. 

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Someone I know near Keswick says the locals knew the £millions spent on the glass wall defence was useless because the water still can't get under the bridge at the end of the street.
All the new wall did was hold it back until it inevitably over-topped again.
Since making the bridge opening larger would be overly cheap and simple, a less grandiose solution would have been to allow water onto adjacent roadway and make a gap in the wall for it to get back into the channel below the bridge.
This would have cost a fraction of the amount and greatly reduced the affected area.

It's like a lot more things - when Government throws money at a problem it's amazing just how much cash can be soaked up.
They can never resist going for the over-complicated but grand looking solution - because obviously announcing spending £30m must be better than spending £30,000 right?

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👍

 

Except the flood defences in carlisle were rated at 1 in 200, so the chance is 4.9%

 

For keswick, it has had events described as 1-in-100 year floods 3 times now, 2005, 2009 and 2015. Take the first one as the base, and what are the chances of 2 more occurring in the next 10 years?

No floods = (0.99^10) = 0.90438

1 flood = (0.99^9) * (0.01^1) * (10!/9!1!) - permutations = 0.09135

2 floods = 1 - (no floods) - (1 flood) = 0.004 (0.4%)

There is nothing political here.  These are facts.

 

This link below is worth open minded consideration.

http://www.bbc.co.uk/news/resources/idt-5aceb360-8bc3-4741-99f0-2e4f76ca02bb

 

Its is the first graphic that I find of note, I'm not bothered about the stuff on climate change as I don't want to start arguing about why the climate is warming so fast - that is indeed for another thread, I'm just pointing out it IS warming fast.

p.s.

Previous warmest first 8 days of December was 10.08C in 1979. So this is easily the warmest start to winter on record since 1772.

 

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The images from the A591 by Thirlmere are like something from a movie but the road near us at Langwathby was also washed away by the Eden, I'm just trying to work out how to post a couple of pics! We were lucky in the end and the river got close but not too close. I work at Eamont bridge which has taken a real hammering but the bridge itself did reopen yesterday after structural damage was fortunately not confirmed. Glenridding and Patterdale has also been hit by what looks like an tsunami. Devastating images but the landslips by Thirlmere are incredible and the road won't be open until at least Easter.

The little road i live by now sounds like the M6 as it is part of the 15 mile diversion for the A686 whilst that remains shut. They're working 24/7 to try and build up the tonnes of earth needed to build the road again. It's just unreal, it really is.

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All mountainous areas are going to get events like this with severe erosion from time to time.
You can see ample geological evidence of debris from flood events.
'We' moved into the area and tidied it up with roads and bridges and houses near the water which are built on areas where flooding will periodically occur.
Just because things seem rather stable for whole lifetimes it does not mean that the processes which scoured out ravines and built debris fields out into the valley has stopped.


A natural stream meanders to and fro through across the valley it runs through, gradually making the valley deeper.
It does not normally stay locked in one place for centuries. Debris builds up in one place while material is eroded from others and during storms there will often be a sudden change of course.
Related to this, a common factor in many incidents is bridges becoming blocked with debris such as trees and stones rolling downstream.
The water is then forced to go around scouring a new channel  - you can see this at Glenridding particularly well.
This issue could be minimised with larger bridge openings, debris traps, and better upstream maintenance such as not leaving fallen trees in the stream bed.
However at the moment the current trendy solution is to place woody debris in the stream bed which is supposed to hold back water (for about 5 seconds in a major flood).

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I was at a client near York yesterday morning and noticed flooding around both the Ouse & Wharfe. The football pitches next to the John Smiths Tadcaster Brewery were under about 6' of water (only the tops of the goalposts were showing)

I presume the flooding from both rivers, as it was on open fields, is making good use of flood plains to keep water away from more important/inhabited areas.

 

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More flooding reported at the glenridding hotel as the rain continues to pour once again. And I have a detour to work tomorrow after another detour to get my son to nursery. although we have survived the flooding so I know that is a very minor inconvenience compared to some of the hell people are going through nearby

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I know John is too humble to post this himself, so I will ......   This is an excellent report/assessment from someone who knows his stuff.   Very well worth reading, and learning from

http://www.skepticalscience.com/december-2015-uk-floods.html

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Just read the article very informative.

Indeed.

I have just deleted that post, Cycles.

This is not the right place/thread for scoring points on climate change.

Over and out.

 

That's a great article, thanks for sharing. The organisation I work for is sitting on the Cumbrian Flood task force and upstream water retention is one of the issues arising in the discussions.

I really hope that we can start looking at slowing the flow of water in the headwaters of catchments to make a longer but lower flood hydrographs and therefore reducing flooding impact. Land management change may work out significantly cheaper than hard defences too. It's got to be worth a try at least as hard defences just don't work in Atlantic River situations.

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And so it begins once again....the Hotel at Glenridding has flooded for the third time in 3 weeks, the flood sirens have sounded at Appleby again and there are various flood warnings in place including where I am currently at Eamont Bridge where only last week the bridge carrying the A6 through the village was condemned due to the floods 2 weeks ago.
The rain is lighter now but the rivers will continue to rise over the next few hours so I think the worst is still to come.

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You & your fellow Cumbrians have my continued sympathy; a shockingly prolonged episode of atrocious weather.

I travelled over Eamont Bridge a few times earlier this year & can still picture it. Have you heard how the river Lowther is near Askham? We drove down a road (past the front of Lowther Castle/Hall) from Eamont[ish] to Askham & it was a stunning drive, especially when the road drops to run almost alongside the river. I can imagine that's been in trouble recently

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Is there any word on how long it will take to rebuild the A591?

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There is talk of it being closed until next Easter, but that has not publicly confirmed. The damage is extensive. 

 

Cumbria County Council engineers have done a couple of videos on the problems they face. . If you root around You Tube you will find them. 

 

It's also a lovely cycle route! I must admit I haven't been down there since the floods. A colleague of mine lives in Askham and travels that way to work and he says it's ok now but he thinks the bridge is still due a proper inspection which of course is still going on and therefore it might still end up being closed which is happening a lot at the mo. the river levels have been too high still for the divers to inspect the footings properly. 

 We had to go to Watermillock by Ullswater on Sunday and the damage done round there is considerable. Obviously Pooley Bridge is also difficult to get to as there has been a landslip on the road in as well as the bridge no longer being there.

My wife is working in Kendal and there is some severe flooding around there again.

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