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Author Topic: How can we prevent urban flooding?  (Read 7216 times)

Offline thedoc

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How can we prevent urban flooding?
« on: 11/12/2012 18:14:25 »
Britain’s continuing wet weather has highlighted a serious problem facing towns and cities – urban flooding.  Rather than soaking through the soil, water in built up areas is blocked by concrete, tarmac and tile and can overwhelm the drains and flood.  But there is an alternative, at least in some areas - SUDS or Sustainable Drainage Systems, with some neat ideas for urban planners...
Read a transcript of the interview by clicking here

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« Last Edit: 11/12/2012 18:14:25 by _system »


 

Offline Mazurka

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Re: How can we prevent urban flooding?
« Reply #1 on: 07/01/2013 17:45:44 »
Anyone interested in SuDS should look at   http://www.susdrain.org/

SuDS have been with Town and Country planning for well over 10 years, however local councils had little power to require developers include them as part of developments, although some did to avoid other problems, or to get round otherwise insurmountbale objections to developments.  The Flood and Water Management Act (when implemented over the next two years) will change this and will give the issue more weight as a "material consideration" in the planning process.

Furthermore, in response to the increasing hardsurfacing of suburban gardens to provide parking, in 2008 the government proposed some changes to "permitted development rights" to restrict the amount of hardsurfacing a householder could create on their property https://www.gov.uk/government/publications/permeable-surfacing-of-front-gardens-guidance  I don't think these ever came into force.

More on the implementation of the Flood and Water Management Act 2010 at 
http://www.defra.gov.uk/environment/flooding/legislation/implementation-approach/

Finally, I disagree that this is a strictly urban problem whislt surface flash flooding in areas away from existing water courses is caused by poor infiltration and urban impermeable surfaces - unsustainbale changes in upland land management and other farming practice (such as large scale land drainage have exacerbated many flooding problems by reducing the length of time that the hills hold their water.  Whilst there is increasing recognition of this problem and drains (aka "grips") cut into peat bogs are being filled in and issues surrounding stock density and reforrestation are being looked into, the only possible conclusion is that we are not managing the land as well as we need to address problems such as climate change (which for the the UK at least, seems to mean increased rainfall. )
 

Offline AlexJohns

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Re: How can we prevent urban flooding?
« Reply #2 on: 08/01/2013 05:47:34 »
Hello Members,

Some ways to prevent urban flooding are:

* Improving Drainage
* Harvesting Rain Water
* Building Dikes and Levees
* Building Canals



Thanks and Regards,
Alex Johns
 

Offline Don_1

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Re: How can we prevent urban flooding?
« Reply #3 on: 08/01/2013 12:17:22 »
Finally, I disagree that this is a strictly urban problem whislt surface flash flooding in areas away from existing water courses is caused by poor infiltration and urban impermeable surfaces - unsustainbale changes in upland land management and other farming practice (such as large scale land drainage have exacerbated many flooding problems by reducing the length of time that the hills hold their water.  Whilst there is increasing recognition of this problem and drains (aka "grips") cut into peat bogs are being filled in and issues surrounding stock density and reforrestation are being looked into, the only possible conclusion is that we are not managing the land as well as we need to address problems such as climate change (which for the the UK at least, seems to mean increased rainfall. )

I am inclined to agree with you on this point.

Although flooding has been a problem in some of our towns & cities, the problem is certainly not confined to the areas of concrete jungle. In October 2012, the Cornish village of Clovelly saw flash floods caused by heavy rainfall. This village, which is some 800 years old, is not prone to flooding nor is it surrounded by concrete or tarmac. It is surrounded by woodland and farmland.

I wouldn't mind betting that there have been more floods in small countryside towns and villages than in London, Birmingham, Manchester etc.

Historically we had a need to build our settlements close to water and some of these settlements developed into the great metropolises. Today, with modern transport and piped water, we no longer need to be beside great rivers or even small streams, but we choose such locations on the grounds of asthetics. Nothing increases the value of property so well as the description containing the words 'sea view' or 'overlooking the river'. The view of a meandering stream from the window is most pleasent, but gentle meandering streams can turn into raging torrents and if your property does command an excellent view of a stream or river, the chances are, you are sitting in the flood plain.

The solution to flooding, is to stop building on flood plains.
 

Offline SeanB

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Re: How can we prevent urban flooding?
« Reply #4 on: 09/01/2013 08:40:57 »
There are certain suburbs here where you cannot get plans passed for non permeable paving, as they are areas otherwise prone to flooding. You have to have french drains and such for rainwater from the roof, preferably a tank as well.
 

Offline CliffordK

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Re: How can we prevent urban flooding?
« Reply #5 on: 09/01/2013 11:02:11 »
Unfortunately, both Urban and Rural areas were not designed with considering 100 yr or 1000 yr flood zones in mind. 

On the West Coast of the USA, putting multiple dams on a watershed can help, although reading and seeing photos of the 1964 floods in Oregon, I do wonder if the current system gives us a false sense of security.

One thing that needs to be considered more in urban planning is asymmetrical flooding of rivers.  Often river banks are naturally steeper on one side, and flatter on another side.  If planned right, it is often fine to build a dike on one side of the river, while allowing an open flood zone on the opposite side of the river.

Problems occur with the temptation to dike both sides of rivers, and to build artificial choke points for the river flow.
 

Offline Don_1

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Re: How can we prevent urban flooding?
« Reply #6 on: 10/01/2013 12:49:56 »
Unfortunately, both Urban and Rural areas were not designed with considering 100 yr or 1000 yr flood zones in mind. 

You can say that again!

The big problem is that unless you have somewhere to drain the water, ie the sea, building defenses in one place only moves the problem somwhere else.
 

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Re: How can we prevent urban flooding?
« Reply #6 on: 10/01/2013 12:49:56 »

 

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