Flooding

[VicParticipant @vic]

Is it now time to tackle the issue of our waterways? Could we stop a lot of the flooding we’re seeing in the North by improving our rivers or is it all too expensive?

**LINK**

[VicParticipant @vic]

[Rod RenshawParticipant @rodrenshaw28584]

Yes, something needs to be done about flooding. In my view, developers have contributed significantly to this problem by building in areas that were traditionally used as floodplains.

Lots of info about waterways in the link, but there is also a lot that could be done to reverse the changes in land usage that have happened over recent years, like deforestation, which have reduced the capacity of upland areas to absorb heavy rainfall and then allow the water to flow slowly into the rivers.

Rod

[Gordon AParticipant @gordona]

As someone who has found it difficult and expensive to obtain insurance cover for flooding, I can only comment on my local area where the trend appears to be that of paving over front gardens in contravention of the SUDS regulations introduced 1st October 2008.

[Brian HParticipant @brianh50089]

I believe that a major factor was the EU prohibition on dredging waterways. I had hoped that with leaving the EU this would be rectified.

Brian

[Martin KyteParticipant @martinkyte99762]

I can't see that dredging is going to help much. Slowing down the run off from catchment areas and creating storage in the form of washes or areas that can flood without harm would be the way to go.

regards Martin

[not done it yetParticipant @notdoneityet]

Posted by Rod Renshaw on 22/01/2021 12:33:45:

….

Yes, something needs to be done about flooding. In my view, developers have contributed significantly to this problem by building in areas that were traditionally used as floodplains.

….

Oh. The developers do this without planning consent, do they? Flood plains will not alleviate all these so called “100 year” storms or rainfall, etc etc, we seem to be seeing this past decade.

[CalumParticipant @calumgalleitch87969]

It's a messy subject and anyone who has simple answers is not to be trusted.

On dredging, there are certainly areas that were historically dredged which enabled building on low ground. It doesn't take a huge amount of insight to see that stopping dredging might not be brilliant. However, dredging in general is ruinously expensive, destructive to the environment, and counter-productive as it just delivers water onto flood-plains faster. Upstream retention activities are useful for protection, but the farmer whose crops are sacrificed to save the town might see things differently. Building on floodplains is hardly ideal but we desperately need more housing and suitable sites aren't always easily found.

And all the while climate change is effectively making the ground everywhere inexorably closer to the water…

[Ady1Participant @ady1]

I used to see it a lot when hillwalking because you can look down from above

Nice old farmhouse hundreds of years old… built on a flat/sloping hillside bit

Loads of modern houses covering the lower broader flatter areas

And there was always a good reason why the 500 year old rich guys residence was 60 feet up on the hillside bit

The nice flat bits are called flood plains, sometimes they only flood once in a lifetime

Edited By Ady1 on 22/01/2021 13:39:14

[OldironParticipant @oldiron]

Posted by Brian H on 22/01/2021 12:36:10:

I believe that a major factor was the EU prohibition on dredging waterways. I had hoped that with leaving the EU this would be rectified.

Brian

Wel,l early days yet Brian but lets hope things improve. The problem is all the "greenies" that say you cannot clean/straighten or clear river banks to aid flow and stop backups. It should be made a priority to clamp down on developing our ancient flood plains. AND bring back the beavers to make a few more dams upstream to slow the flow.

(I know nothing)

regards

[SillyOldDufferModerator @sillyoldduffer]

Posted by Brian H on 22/01/2021 12:36:10:

I believe that a major factor was the EU prohibition on dredging waterways. I had hoped that with leaving the EU this would be rectified.

Brian

The EU does not forbid dredging, and nor does the UK Regulation. The present flooding is a different problem and far more difficult to fix. The Water Environment (Water Framework Directive) (England and Wales) Regulations 2017 has many escape clauses:

15.—(1) The appropriate agency may designate a body of surface water as artificial or heavily modified if it considers that—

(a)the changes to the hydromorphological characteristics of that body which would be necessary for achieving good ecological status would have significant adverse effects on—

(i)the wider environment,

(ii)navigation, including port facilities, or recreation,

(iii)activities for the purposes of which water is stored, such as drinking water supply, power generation or irrigation,

(iv)water regulation, flood protection, land drainage, or

(v)other sustainable human development activities which the appropriate agency considers are of equal importance to the matters in paragraphs (i) to (iv), and

(b)the beneficial objectives served by the artificial or modified characteristics of the water body cannot, for reasons of technical feasibility or disproportionate cost, reasonably be achieved by other means which are a significantly better environmental option.

Repeats spells of unusually heavy rainfall is the hard to fix cause of flooding, and it's mostly likely due to Global Warming, which predicts more frequent and larger severe weather events, exactly as are being reported all over the planet.

Part of our flood problem lies in 20th Century planning assumptions being torpedoed by climate change. When no-one believed in climate change, it was assumed severe weather events likely to impact building projects would only occur once per century, which is an acceptable risk. Unfortunately, the assumption is proving wrong. 'Once per century' events are occurring in quick succession causing insurers to walk away.

Prevention schemes can only reduce flood risks up to a point. Flood damage is inevitable every time Mother Nature delivers more rain than can be drained away. It's possible to provide some protection, but in many cases the simple answer is to not build in areas liable to frequent flooding! Returning flood plains to their natural condition would help. They provide flood protection by giving water somewhere to sit safely before rivers burst their banks. It's unlucky they also made prime building land, and their becoming an overflow is so painful to residents.

Returning flood plains to their natural condition may be inevitable. People won't be able to live on land that floods every other year with no chance of relief: they will have to move. Repeat flood risk properties become impossible to insure or mortgage.

Dave

[Clive HartlandParticipant @clivehartland94829]

Breed more beavers, we plant more trees and the Beavers can chew them down!

[noel shelleyParticipant @noelshelley55608]

One person on here will not want to read this ! In the village of Heacham in Norfolk, The biggest village in the land. In the middle was a large area un built on – until the 1980s.It was surrounded by houses and locals knew it as wet meadows for cattle grazing. The sea is less than a mile away but the planners let it be built on – they didn't care how many pumps would be needed to keep it dry ! Electric pumps ! On another occasion houses were built on the village pond, not withstanding that it was the drain for the area. It would be mischief to think there was something in it for the planners, but they would hear no argument against the plans.

Dredging waterways, the Dutch don't dredge the canals ?

Ah well. Noel.

[J HancockParticipant @jhancock95746]

What the Dutch have been 'doing ' since '46 ish.

Google 'Delta Plan'.

[pgk pgkParticipant @pgkpgk17461]

..even with the best planning..

I have a stream that runs past the barn apron, drops into a large silt sump and under the drive to the next stream section. It's dry in the summer, a moderate trickle in the winter and a torrent after flash rains. The entrance to the sump is protected by a domed grill coverd with an old bird cage and a few upstream grills to trap debris. I reinforced and upgraded the lower sides during the summer.

I'm used to checking it daily when it's wet and clearing any leaves etc. It's been very good this year. During the storm I went out and checked on it – all good and clear. Half an hour later i went to get something from the barn and everything was awash with a torrent of overflow – a sudden flush of debris had overwhelmed the whole system.

Fortunately (and from past experience) everything important in the barn (freezers, feed bins) is raised up on concrete blocks.

If you have to build on flooplains (once in a life-time = every year) then build the blasted things on stilts.

But there's no reason why you can't build on less useful hills and move commerce there rather than destroying good alluvial soils.

pgk

[not done it yetParticipant @notdoneityet]

TBH, my previous post only addressed the flood plain building and “100 year” weather events.

This really started in the late’50s when farmers were given grants to drain their land. What used to be soggy fields in the winter became much more easily cultivated afterwards! Latterly, huge field have been produced by grubbing up hedgerows and filling in the small ditches that often ran aside them.

Even more recently, huge areas of forest land have been heavily utilised, cutting down the whole lot and replanting – not good for rainfall retention – and heavy machinery is used in the large aforementioned fields, leading to immediate run-off when heavy rain occurs.

These (and others) are reasons why floods are more prevalent these days – apart from the obvious low-lying building and climate change. I expect more places are being flooded up-stream, because the water would otherwise drown out far more of the low-lying building sites.🙂

[Dave HalfordParticipant @davehalford22513]

They built a new estate my way in the 70's. The existing road at the low end was called Watery Lane.

Can't think why.

[Mike PooleParticipant @mikepoole82104]

Rainfall on the Chilterns arrives in our village brook within hours of falling and floods the village high street. I don’t think any of the old cottages ever flood but a few new build properties have been flooded in recent years. One new build has built a perimeter wall around the entire property with sealable gates, it tickles me when I think if the house had been built with another few courses of bricks to the floor level the house would be safe.

Mike

[Neil WyattModerator @neilwyatt]

Posted by not done it yet on 22/01/2021 13:09:19:

Posted by Rod Renshaw on 22/01/2021 12:33:45:

….

Yes, something needs to be done about flooding. In my view, developers have contributed significantly to this problem by building in areas that were traditionally used as floodplains.

….

Oh. The developers do this without planning consent, do they? Flood plains will not alleviate all these so called “100 year” storms or rainfall, etc etc, we seem to be seeing this past decade.

No, they build in flood plains with planning consent, perhaps less often now than in the past.

Usually flood works and mitigation is required but it is not always effective.

Neil

[Neil WyattModerator @neilwyatt]

Posted by Vic on 22/01/2021 11:56:54:

Is it now time to tackle the issue of our waterways? Could we stop a lot of the flooding we’re seeing in the North by improving our rivers or is it all too expensive?

**LINK**

I've had the good fortune to work closely with people, from the National Rivers Authority and then the Environment Agency over the last 30-odd years. It's amazing how complex it all is and how sometimes the most effective solutions are counter-intuitive.

One of the ironies is that river 'improvement' in terms of straightening them out and using flood defences to allow development of low lying land has proven to be one of the main problems for causing flooding.

It works well if you are coastal – like London, but not if you are further upstream. It increases peak flows, more rapidly passing pulses of water to lower lying areas and places a greater strain on unprotected areas.

That's why there is such enthusiasm for creating more 'natural' channels in agricultural areas, slowing down the passage of water and encouraging it to flood low-lying pasture which typically recovers quickly. This greatly widens and lowers the size of the 'pulses' of water that cause dangerous flooding.

This is also why building in flood plains is such a problem. Especially in the (relatively recent) past but still sometimes these days, houses usually get defended by engineering works but even with works to 'compensate' for lost floodplain capacity the margins for protecting other areas can be eroded.

Things like restoring peatlands, so they can hold (and slowly release) more water and replanting woodland that otherwise intercepts and slows heavy rain.

These have been found to be far more effective than old-style approaches like large engineered overspill areas (which don't always function as designed).

A lot of local flooding is caused by rapid surface runoff from agricultural land, especially when the soild is bare, if it has lost many of its hedgerows and ditches – to the chagrin of farmers who sometimes see their precious topsoil heading off down roads and streams.

Even reintroducing beavers can help – over ten years beavers on the River Otter (sic) have resulted in reduced peak flows due to their dams slowing peak flows.

For anyone who has a GIS on their computer there is a massive amount of free information on various levels of flood risk under the Government Opendata arrangements – it can be fascinating to explore your local area.

Neil

[JohnFParticipant @johnf59703]

But there's no reason why you can't build on less useful hills and move commerce there rather than destroying good alluvial soils.

pgk

Plus one for pgk's last statement, I have advocated for many years in modern times its is crazy to build on prime agricultural land that we need to feed ourselves.

Far better to build on less productive land wherever that may be — I can already hear the screams of anguish but better than screams of hunger in many years hence – bonus no flooding of homes !

[larry phelan 1Participant @larryphelan1]

Shame on you Noel !!!

Do you really think that such "Noble" people would stoop so low ?

Dont answer that !

Simple fact is that concrete does not absorb water nearly a s well as good old soil.

What now Batman ?

PS I seem to remember that something similar happened in North Korea some years ago when they decided to cut down most of their trees in order to sell the timber for quick profit. Turned out it was not such a good idea.

To all the smart-arses out there, dont try to teach Mother Nature how to suck eggs.

[David George 1Participant @davidgeorge1]

I live on a hillside which is made up of layers of alluvial sand and clay some deep bedded and some shallow. Layed down at the end of the last ice age it is a great source of casting sand and much quarried all over the years and is still being now. When it rains the sand absorbs the rain and purcolates down till it reaches a clay layer which when saturated produces a spring. These springs used to and still appear after a wet spell and occasionally are quite interesting sometimes especialy if it is under your house as there are a few on the estate. Some households have removed the suspended floor and concreted with a waterproof membrane to get rid of the problem which they may have, some have dug soakaways which seem to remove the problem from there property passing the problem to another property slightly down hill so next door with a couple of court cases that I know of. After an extension had been built along the street I live in a front garden started to sink and a large sink hole appeared which appears to have been caused by an underground stream being diverted into a soakaway, specified by the council, starting to undermine house fiundations as well. The council has put in a ditch across the hillside with a concrete pipe to the nearest river to try and remove some if the problems but through lack of maintenance and poor thought out design the pipe gets blocked and when it is free the local stream floods older properties along its course. It's a complicated area and you wouldn't this k you would get flooded on a hillside.

David

[Chris Evans 6Participant @chrisevans6]

Mans interference tends to be a major problem. The river Trent runs through my village and floods where the river was straightened out. Fortunately far enough away from me.

[VicParticipant @vic]

I used to live in west London close to the Thames. As a child it would flood the High Street every few years. After they build flood defences (concrete wall) it never happened again.

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