Floods and droughts?

[pequod]

The new Thames Tideway Tunnel is part of the solution for London, at least, and may be necessary to construct other similar 'super sewer' elsewhere.

[Pan Pan Pan]

vaud said:

It is not cheap, and we have an infrastructure legacy that the US did not have in the build out of some cities.

If you are starting with a blank sheet then a lot more is possible.

Absolutely. I doubt if anyone believes that the construction of such infrastructure is going to be anything but colossally expensive, and hard to achieve, no matter how much cash is made available.
However, I wondered that given the `predictions' by some, that these flooding events are `predicted' to be more, rather than less likely to occur in the future, and that we are also `predicted' to be getting more hot, dry summers where the availability of enough potable water for the population may be also problematical with our current water storage capacity, It seems a logical step to construct something that helps reduce the likelihood of flooding happening in the winter, whilst at the same time providing increased water capacity for use in the `hot dry' summers we are alleged to be facing, when it may be in short supply.

[BoRED S2upid]

How much would a new reservoir cost to build in the U.K.? Back in the day you built a fek off wall and flooded a valley. Nimbies and eco warriors would go mental at such a though in the U.K. today.

We have had a biblical amount of rain in recent weeks and we haven’t had a drought in the U.K. for decades.

[Fittster]

BoRED S2upid said:

we haven’t had a drought in the U.K. for decades.

Evidence for that?

https://en.wikipedia.org/wiki/List_of_droughts

[BoRED S2upid]

Fittster said:

Evidence for that?

https://en.wikipedia.org/wiki/List_of_droughts

Not Wikipedia. According to that we’ve had more droughts than Africa.

I pretty much can’t remember a year in my 40years on this planet when water didn’t flow from my tap and there was a shortage of the stuff.

[vaud]

BoRED S2upid said:

Not Wikipedia. According to that we’ve had more droughts than Africa.

I pretty much can’t remember a year in my 40years on this planet when water didn’t flow from my tap and there was a shortage of the stuff.

Bradford areas in 1995. Water bowsers on the ends of some streets.
Water being moved by lorry under emergency rules.

https://www.bbc.co.uk/news/uk-england-13815317

[Mrr T]

BoRED S2upid said:

Fittster said:

Evidence for that?

https://en.wikipedia.org/wiki/List_of_droughts

Not Wikipedia. According to that we’ve had more droughts than Africa.

I pretty much can’t remember a year in my 40years on this planet when water didn’t flow from my tap and there was a shortage of the stuff.

You cannot remember 2010-2012?
Reservoirs in the SE where vertually empty and the water table at very low levels. Hose bans for most of the time.

[slipstream 1985]

Re the floods here is my solution

https://goo.gl/maps/3xxtjhqVeVk2CVS66

Build a reservoir here. Link the Severn at the narrow point where they turn away from each other. Dig out the isle area or more it seems like a natural bowl kinda area anyway. Cost some land and one hotel/country house.

[shoestring7]

Nimby said:

TPSA7514 said:

Isn't part f the problem building houses on land that was used for flood plains

This plot with planning permission is currently several feet below the River Severn.

Its perfectly possible to build a house on that site: here's one next to the River Thames in Dorchester: https://www.wowhaus.co.uk/2018/07/06/1960s-fieldin...

[gazapc]

slipstream 1985 said:

Re the floods here is my solution

https://goo.gl/maps/3xxtjhqVeVk2CVS66

Build a reservoir here. Link the Severn at the narrow point where they turn away from each other. Dig out the isle area or more it seems like a natural bowl kinda area anyway. Cost some land and one hotel/country house.

Just measured this in Google Earth, if you built a 2km x 0.8km reservoir, with a depth of 5m you could hold 8million m3 of water.
A preliminary google search suggests a historic peak flow rate at Bewdley of 630m3 per second.
All that engineering means you can divert the entire flow for around 3.5 hours, if you want to divert 20% of the flow, you can do it for a bit less than 18 hours.

[saaby93]

They have upstream reservoirs upstream anyway. The problem is they dont know how to manage them.

All you have to do is check the BBC news website for a reservoir reaching full and they open the flood gates
Just at the same time as the river is already in full flood

Isnt there a way of keeping the reservoir levels low before a big storm piles not - not after?

[irc]

The money that could be used to build flood defences and reservoirs is being used to try and cut our CO2. Which is a bit pointless because no matter what we do with our 1% of world CO2 China, India etc will keep producing more.

Low CO2 electricity costs £11BN a year and is going up.

.https://notalotofpeopleknowthat.wordpress.com/2020/02/11/green-subsidies-will-continue-to-push-up-power-prices-for-years-to-come/

Meanwhile around half a billion a year is spent on flood prevention.

https://www.theguardian.com/politics/2019/nov/13/d...

[turbobloke]

irc said:

The money that could be used to build flood defences and reservoirs is being used to try and cut our CO2. Which is a bit pointless because no matter what we do with our 1% of world CO2 China, India etc will keep producing more.

Low CO2 electricity costs £11BN a year and is going up.

.https://notalotofpeopleknowthat.wordpress.com/2020/02/11/green-subsidies-will-continue-to-push-up-power-prices-for-years-to-come/

Meanwhile around half a billion a year is spent on flood prevention.

https://www.theguardian.com/politics/2019/nov/13/d...

Exactly.

[FiF]

gazapc said:

slipstream 1985 said:

Re the floods here is my solution

https://goo.gl/maps/3xxtjhqVeVk2CVS66

Build a reservoir here. Link the Severn at the narrow point where they turn away from each other. Dig out the isle area or more it seems like a natural bowl kinda area anyway. Cost some land and one hotel/country house.

Just measured this in Google Earth, if you built a 2km x 0.8km reservoir, with a depth of 5m you could hold 8million m3 of water.
A preliminary google search suggests a historic peak flow rate at Bewdley of 630m3 per second.
All that engineering means you can divert the entire flow for around 3.5 hours, if you want to divert 20% of the flow, you can do it for a bit less than 18 hours.

Just to put that in perspective, will compare it to a current project in my area, the Birmingham Resilience project. Water currently comes down the Elan Valley aqueduct, this needs maintenance, so a new pipeline is being built to extract water from the Severn at Lickhill, downstream from Bewdley, and pump it to Birmingham storage facility. So it's easy to think, well in times of flood pump that water somewhere.

Some background.
Extraction point at Lickhill chosen as riverbed contours this is best place for extraction.
23km of pipeline required, pic shows some arranged out ready for laying etc.



Three tunnels have been bored  with tunnel boring machine



The pumphouse will house 4 pumps, I forget MW power figures, 3 working, 1 on standby. These pumps require so much electricity that the town supply was insufficient and dedicated supply needed from a major switching station, which itself needed work. It used to be next to a power station so isn't exactly small.

300 million pound project started in 2015.

This is to run 24/7 during winter and extract 130 megalitres per day, deliberately limited to avoid affecting flow too much, but which calculates out at 130,000 m^3 per day. Severn has been running at over 50,0000,000 m^3 per day for some time now.

That's the scale of the problem.

Plus where do you pump it too. Reservoirs already full.

[Biker 1]

Looks like the flood defences are not up to it: https://www.bbc.co.uk/news/uk-england-hereford-wor...
My hydrodynamics skills are a little rusty, but some aluminium poles & a roll of plastic ain't going to stop the Severn.....

[FiF]

It's not just the mechanics of the temporary defences. For example another issue at Bewdley on Beales Corner before the overtopping is the state of the bank. When the water gets high enough the increased pressure means water is driven through the bank wall, through the earth and pushes up the tarmac behind the barrier.

That's before you even get to the consideration of water seepage into tarmac, freezing temperatures forecast, hence widespread infrastructure damage on top of direct flood damage. Pothole central.

[vonuber]

Biker 1 said:

Looks like the flood defences are not up to it: https://www.bbc.co.uk/news/uk-england-hereford-wor...
My hydrodynamics skills are a little rusty, but some aluminium poles & a roll of plastic ain't going to stop the Severn.....

The flood defences would have been designed to a certain standard. Eventually an event will happen which will over top / reach them.

[ShoooRn]

I've had a browse again of the Environment agency map http://apps.environment-agency.gov.uk/wiyby/37837.... for the flood plains in the UK and honestly they seem tweaked to when I was younger. Alot of where new developments are being propped up alongside rivers (that I know that flood and have witnessed) are not marked as a flood zone but plenty of older built properties can be found in flood zones.

There's a new build of an industrial park near me thats had to rethink its strategy and create two large pond/small lakes for water storage it seems right in the middle of where one factory was going to sit.

[slipstream 1985]

gazapc said:

slipstream 1985 said:

Re the floods here is my solution

https://goo.gl/maps/3xxtjhqVeVk2CVS66

Build a reservoir here. Link the Severn at the narrow point where they turn away from each other. Dig out the isle area or more it seems like a natural bowl kinda area anyway. Cost some land and one hotel/country house.

Just measured this in Google Earth, if you built a 2km x 0.8km reservoir, with a depth of 5m you could hold 8million m3 of water.
A preliminary google search suggests a historic peak flow rate at Bewdley of 630m3 per second.
All that engineering means you can divert the entire flow for around 3.5 hours, if you want to divert 20% of the flow, you can do it for a bit less than 18 hours.

Thanks for doing the math I'm just an ideas man. There is scope to double or tripple the area nearby and could you go deeper? Tag in a hydro electric planty or two into it and doublle up on it's uses. You could justify using the carbon reducing fund rather than flood defence fund for it.

[Pan Pan Pan]

slipstream 1985 said:

gazapc said:

slipstream 1985 said:

Re the floods here is my solution

https://goo.gl/maps/3xxtjhqVeVk2CVS66

Build a reservoir here. Link the Severn at the narrow point where they turn away from each other. Dig out the isle area or more it seems like a natural bowl kinda area anyway. Cost some land and one hotel/country house.

Just measured this in Google Earth, if you built a 2km x 0.8km reservoir, with a depth of 5m you could hold 8million m3 of water.
A preliminary google search suggests a historic peak flow rate at Bewdley of 630m3 per second.
All that engineering means you can divert the entire flow for around 3.5 hours, if you want to divert 20% of the flow, you can do it for a bit less than 18 hours.

Thanks for doing the math I'm just an ideas man. There is scope to double or tripple the area nearby and could you go deeper? Tag in a hydro electric planty or two into it and doublle up on it's uses. You could justify using the carbon reducing fund rather than flood defence fund for it.

Perhaps the trick is not to try to divert the entire flow from swollen rivers but to divert anything above normal flow for the time of year, from the rivers into a newly constructed catchment area, in a given area.
Any valley which is dammed to form a catchment area could be many metres deep., A reservoir only 5 metres deep would just be a shallow pond, and hardly worth the effort of forming it.
Such infrastructure would be colossally expensive, but would represent a one off solution that might at least last for a decade but possibly longer, if all that excess fresh water is taken out of it to meet demands during the hot summers some have predicted we are going to get.
But back to reality, we currently have areas that are underwater (again), but give it a few months and we could be getting hose pipe bans, and other water usage restrictions (again)
Just seems we are`nt doing something quite right, when it comes to practically dealing with the `actual' weather conditions the UK seems to getting these days.