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View Full Version : Sandbags - There's got to be something better?


Mechta
3rd Jan 2014, 21:14
Watching the current flooding in the UK, the same as we get every other year, does it strike any other Ppruners that sandbags are a pretty useless form of flood defence?

Has anyone got any better ideas for keeping water out?

radeng
3rd Jan 2014, 21:16
Live further up a hill?

Gertrude the Wombat
3rd Jan 2014, 21:24
Live further up a hill?
That works for new build (in areas where the planning authority chooses to take flood risk, SUDS, etc, seriously) but is hard to retrofit.

radeng
3rd Jan 2014, 21:28
But not to take into account when you buy/rent/choose to live there.

Capetonian
3rd Jan 2014, 21:29
I am amazed how many dwellings are built in flood plains and areas subject to flooding. I am watching a house being built on a sloping plot that has a watercourse running through it, which bursts its banks whenever there is heavy rain - at least twice a year. I imagine the purchasers did not undertake a survey or due diligence and will only have themselves to blame when they wake up under water.

Private jet
3rd Jan 2014, 21:37
Move to the fens? A built in flood defence system?

G-CPTN
3rd Jan 2014, 21:49
30-odd years ago, when house-hunting in Somerset (Avon, actually) I went to look at a delightful cottage with a stream (complete with watercress beds) that ran through the garden.
The house itself was built of brick - which was darker in colour lower down. There was a distinct line about two feet up with lighter-coloured brick above the line.
I asked what might have caused this effect and was told (honestly) that that was where the last flood had reached.

I made my excuses and left immediately.

Station_Calling
3rd Jan 2014, 21:57
Try these:

Self Closing Flood Barrier - Operation - Global Flood Defence (http://www.globalfloodds.com/selfclosingfloodbarrieroperation.aspx)

Sandbags are way cheaper though...

Nearly There
3rd Jan 2014, 21:57
Sandbags have a use protecting structures from damage caused by flowing water by diverting the destructive force of it, but pooling rising flood water they're pretty useless.

Mr Chips
3rd Jan 2014, 21:58
I thought sand bags were effective? :confused:

seafire6b
3rd Jan 2014, 22:29
Sandbags - about as useful as collecting iron-railing fences to build Spitfires. I think the theory's pretty much the same too - while filling and positioning the bags, you think you're doing something to avoid being overrun!
Speaking from experience, many years ago.

Mechta
3rd Jan 2014, 22:43
Station_Calling, I like that 'Self Closing Flood Barrier'! I just hope it works after having had a year of leaves and earth fall in the slot.

It strikes me that a heavy board with a windscreen wiper type seal dropped into a slot around the bottom of a door would do the job better than sandbags, with a lot less back breaking effort to install. The other thing is to survey one's property in advance and make sure all ventilation and other holes are plugged.

As far as I can see, the builders of water mills and other buildings necessarily near flood plains regarded annual flooding as an occupational hazard for the occupants. Its only nowadays that the occupiers of properties in such areas regard it as someoneelse's fault that their quaint abode is in regular need of new carpets and redecoration.

A Dutch colleague at work told me about a house in the Netherlands which had a 'tanked' basement. When the floods came along, the whole house floated up out of the ground on its basement 'hull'... Probably not what was intended though...

Fox3WheresMyBanana
3rd Jan 2014, 22:56
Radeng is right - don't buy a house that's prone to flooding. Eventually, builders will get the message.

G-CPTN
3rd Jan 2014, 22:58
Neighbours who have a house built squarely within the flood-reach of the river, had the building 'tanked' (coated with bitumen then a stone wall built up to a height of nearly three metres) and all drainage services rerouted to prevent feedback and all entrances apart from the front (main) one 'bricked-up'.

The remaining entrance is fitted with a series of panels which can be slotted into guides that then prevent the floodwater from entering.

Whenever flooding is predicted, they move their vehicle to higher ground (their house is at the bottom of a steep hill) and decide whether to be 'within' or 'without' as once the river rises the house becomes surrounded fairly early (rising up to two metres in extreme circumstances).

Carry0nLuggage
3rd Jan 2014, 23:02
Fox3 - I doubt it. Round here developers have been trying for years to have a go on an area known as "The Causeway".


Perhaps if flood insurance was impossible to get or stupendously expensive the message might trickle through.

Fox3WheresMyBanana
3rd Jan 2014, 23:04
I thought the UK Government imposed requirement for Insurance companies to provide flood insurance had now ended?
Thus it ought now to be impossible to get flood insurance for properties that regularly are (or are likely to be)?

SawMan
3rd Jan 2014, 23:44
Sandbags are no more 'waterproof' than sand at the beach, but this 'fact' changes with floodwater which is usually dirty, and that dirt can reduce and almost close off the water flow through the sandbags. Even if they were totally impervious, water would flow through the ground underneath them because of the pressure differential. Short of building a permanent structure, there's still not an better solution than old-fashioned sandbags when the economics of scale comes into the picture. In the end, there is no real defense to a flood event save for remaining above it :ok:

I don't know how the system works in the UK, but in the US the builder does the construction while the developer sells the property lots. Having the two separated makes sense as the two businesses have little in common save for coming together at the same place- they are totally different things which require different skill-sets to handle. Here, it is the developer who chooses where the building sites will go, and in the US they usually cannot be in a known flood-plain unless they are built to withstand that expected level of flooding. Older homes here may have flooding issues because they were built before these laws came into effect; newer homes rarely flood but codes and laws vary so you have to check on this to be certain that you're not doing something as stupid as buying a flood-prone home! I'm a builder- NOT a developer- and if I were I would never buy or sell flood-prone locations. I have too much pride to rip people off like that :cool: Nor will I build on your previously-purchased lot if flooding may be an issue, though somebody else will be happy to take your money- caveat emptor!

vee-tail-1
4th Jan 2014, 00:18
Living in a watermill only 4 metres from a Welsh river has been quite frightening of late. The surrounding land is totally saturated, and any rainfall causes the river to rise within minutes.
The main problem however is the very strong winds which have felled trees and sent loads of debris into the river. Any blockage will cause the river to burst its banks, so I have been busy with the chainsaw to clear the worst. But there are limits and yesterday a massive beach tree fell from one bank to straddle the river. It took out an alder on the other side so the two huge trees have made an instant weir. Next heavy rain the river will move sideways and goodness knows what will happen. But no way do I want to stand waist deep in a fast flowing river using a chainsaw!
Fortunately this is 1/4 mile up river from the mill house and buildings, but the resulting debris could come down and cause a flood. We have boards and sandbags around external doors, not to remain water tight but to ward off the logs and tree branches coming down river at frightening speed. Still we at least have solid ground floors, and all electrics a metre or more above. My family are ready to put soft furniture on top of the big kitchen table if required, and all the kitchen units have drain holes at floor level to let the water out if it comes in.
We are prepared, but those poor people on the coast are going through hell.
:(

Fox3WheresMyBanana
4th Jan 2014, 00:21
Best of luck!

A A Gruntpuddock
4th Jan 2014, 00:29
In the UK, councils routinely refused planning permission for building in flood-prone areas.

A group of developers went to court, saying that it was up to the developers & house buyers to decide whether the risks were worth it and that measures could be taken to mitigate/ minimise the risks.

They argued that refusal of permission interfered with the land owners rights to use their property as they saw fit.

Court ruled that denying permission was unlawful, leaving developers to build but without any guarantee that buyers would be fully informed about the very high probability of flooding.

This should be picked up by lawyers carrying out the usual 'searches' in relation to the land, but what if the developer offers free conveyancing as part of the deal?

I know of at least one case where people bought houses in a peaceful countryside plot and were appalled to find a dual carriageway being built at the bottom of their gardens.

Land was probably bought cheaply because of 'planning blight', but the house buyers were given free conveyancing so never had independent lawyers to alert them to long-standing plans for what had been intended as a very busy motorway.

Hydromet
4th Jan 2014, 01:55
When I took up one job (I was a hydrographer/hydrologist), my predecessor was leaving. He had been on the local council, and because of his knowledge of local flooding, had fought strongly against approving a particular area of floodplain for development. First he was the subject of an attempted bribe. Then there were threats. He decided the game wasn't worth the candle, quit the council and moved on to a better job.
Shortly after the development was completed and the houses sold, they were hit by a record flood.
I've seen people with flood marks half way up their wall deny that they were flooded, as it would devalue their house.

Every method of flood protection has its advantages and disadvantages, but in general, their are few engineering solutions, only planning ones. Sandbags can divert small floods or help protect small areas, but they're not going to do anything against a big flood. Permanent levees can protect if they're big enough and maintained, but if they fail, they can cause more damage than if natural flooding was allowed. Also, they can impound water that causes more crop and property damaged.

What is sometimes referred to as "Munro's Law (http://adb.anu.edu.au/biography/munro-crawford-hugh-11198)" states that if you've had a flood, you'll have a bigger one.

mrangryofwarlingham
4th Jan 2014, 05:46
Sandbags by themselvves serve fa purpose. you see pictures with people with 3 sandbags on their doorstep. wtf is that going to achieve?

if they are being used to hold in place an impervious membrane, where the edges are dug in / sealed, then fair enough - but why people think a line of them across their threshold will help:ugh::ugh:

Loose rivets
4th Jan 2014, 07:28
I've spent ages trying to make these smaller in Photobucket's edit. I've shown these before and the size was fine. Even reduced, they're too wide.:confused:


We live near to this:

http://img.photobucket.com/albums/v703/walnaze/Edinburg/6e93180a-b3af-4573-a7c7-9ff7ca43e0ac_zpsda2e52f7.jpg (http://smg.photobucket.com/user/walnaze/media/Edinburg/6e93180a-b3af-4573-a7c7-9ff7ca43e0ac_zpsda2e52f7.jpg.html)



For years I wondered if I should insure for flooding, but didn't bother. Recently, I've learned from my surveyor neighbor that the water is pumped up from the Rio Grande and this explained why when flooding was even hinted at, the canal emptied. Phew!

Down at Walton on the Naze the yacht club and the old mill can flood right up to the High Street. Folk have a ditch and raised bank to avoid the disaster of 53 being repeated. Near the Town Hard, there is a wall with steel gates but a few houses are on the backwaters side. One man, a local boat builder, seems to have his house as an upside down house. This is what we did just a mile away, though for us it was for the view. When the big flood came, it stopped at our back fence and delivered 5 galls of Castrol oil which I used for years.

I took this of our school. It's well above the town hard level and the water peaked at about a metre up the old redbrick buildings.



http://img.photobucket.com/albums/v703/walnaze/Home/Schoolfieldflood.jpg



Folk here in Texas use sandbags. They sometimes even put plastic sheeting under them. Not much point when everything is made of ticky-tack

OFSO
4th Jan 2014, 08:08
The town of Roses is at sea level with a stream running down into it from the mountains above. The locals living either side of the stream have two metal channels screwed either side of the front door into which heavy boards can be dropped. Of course they are not watertight but do keep the pressure out. Some of the shops which are closed outside the summer season simply have pots - thick fired bricks - plastered across the entrances up to abt 2' high - in early autumn and removed in the spring.

probes
4th Jan 2014, 08:09
I was thinking of these

http://i.telegraph.co.uk/multimedia/archive/01455/treehouse-1_1455974i.jpg

but veetail's " ...the very strong winds which have felled trees..." made me think again. :sad:

Lon More
4th Jan 2014, 08:45
Now flooding for the the third time since Christmas.

WET WET WET DUMFRIES 30 12 2013 - YouTube

There have been plans to "do something" as long as I can remember and finally the Council ha responded by providing a Flood Pod (http://www.dumgal.gov.uk/index.aspx?articleid=10643)
I read somewhere that the Thames Barrier is in danger of being overwhelmed in the near future. Raised 130 tines since it was built, expected to be raised 10 times in the coming week.

G-CPTN
4th Jan 2014, 10:41
0hgAWyEMloE

tony draper
4th Jan 2014, 11:46
Someone on the news yesterday suggested something I suggested last year,start dredging the bloody rivers again,it must help.
:uhoh:

cattletruck
4th Jan 2014, 11:58
Or build more rivers :}

Sandbags are good at keeping the water snakes out of your house.

G-CPTN
4th Jan 2014, 12:03
There are two islands accreting either side of the only bridge across the Tyne to withstand the great flood of 1771.

In the 1940s and 1950s these were kept in check by the local builders who would regularly harvest the sand and gravel to use as aggregate for their construction projects, but, of late the extraction of gravels from waterways has been prohibited as it affects the natural development of the watercourse (!).

The islands have acquired their own vegetation (which binds the gravel against erosion) whilst the mass of the islands impedes the flow of water through the bridge, slowing the flow so that it dumps the silt and gravel that would otherwise be carried further downstream and perpetuation the accretion of the islands.

Those who remember (and have photographs of) the river devoid of islands have not been able to persuade the authorities to remove the islands to alleviate the flooding that occurs more frequently and before they cause the destruction of the bridge - the islands raise the level of the river as it struggles to pass under the bridge.

The vegetation on the islands is now judged to be a wildlife habitat and is therefore 'protected'. :ugh:

Solid Rust Twotter
4th Jan 2014, 12:31
Watercourse maintenance budget back home is better spent on bonuses and luxury vehicles for the pilferati, so the rivers are clogged with deadwood and vegetation. Result is that every year floods cause chaos and people then scream for govt help costing far more than the maintenance budget. Of course that money is also gone, so NGOs end up carrying the can.

...As usual...



We've come a long way.

dubbleyew eight
4th Jan 2014, 12:49
the thai government uses sandbags for flood work.

the thai people in the city just build a brick wall and cement render it.
if the cement sets before the flood hits it is a waterproof wall.
after the flood has gone they just demolish the wall.

racedo
4th Jan 2014, 14:21
Someone on the news yesterday suggested something I suggested last year,start dredging the bloody rivers again,it must help.
http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/worry.gif

Farmer I know in Shropshire said council came along a couple of years ago and dredged all the ditches to make the water drain away quicker. He and his neighbours just smiled.

Whole point of ditches was to take water from the fields slowly and feed into watercourses slowly.

Water quickly drained from his fields as did everybody elses and just piled up further down river.

Dredging the rivers will help but you need the land to hold the water and release slowly.

Lon More
4th Jan 2014, 14:37
Racedo that is the point that was made in the Netherland several years ago after large areas in the centre of the country had been only a couple of hours way from evacuation.
he canalisation of the rivers was also blamed, but the biggest problem was that, often due to building work, the land was draining too quickly. There has been considerable expenditure to better define the area at risk of flooding, the winter bed, and this is being developed as nature reserves.

airship
4th Jan 2014, 14:49
For much of the recent "flash" and/or "temporary" flooding recently, I also wondered why in addition to the half a dozen or so sandbags local councils delivered to block a doorway...:

Didn't also deliver a "doorway-wide" or else suitably-sized sheet of 1/2" 3/4" thick plywood "to be cut-down to measure", perhaps 2 or 3ft high + 3 or 4 cartridges of polyurethane expanding foam? The idea being that the sandbags serve to divert / protect the doorway, the plywood and expanding-foam provide the "water-proofing" against water ingress.

Of course, unless the main waste-water / sewage pipes to the dwelling are equipped with "shut-off" valves, expect "back-flow" into sinks and toilets etc. depending on the severity of the flooding...?! :8

racedo
4th Jan 2014, 16:10
Don't think councils should deliver anything gratis............you want it you pay for it.

Expanding foam idea must admit is good one as while a bugger to clean up after its less hassle than a foot of water.

racedo
4th Jan 2014, 16:17
Mate lives close to Gatwick and he said flooding bad all along River Mole, also pointed out that Gatwick run off is discharged into it which caused lots of problems further along.

Wondered whether in light of fact that new Gatwick runway is likely to be built then where would all this run off go ?

He suggested giant reservoir between runway but I pointed out bird problem, but he said covering it avoids that plus in times of weather as at present it can hold lots of flood water to release a week later. Not such a crazy idea....

Mechta
4th Jan 2014, 16:27
Of course, unless the main waste-water / sewage pipes to the dwelling are equipped with "shut-off" valves, expect "back-flow" into sinks and toilets etc. depending on the severity of the flooding...?!Like this perhaps (bottom row of products): http://www.floodgate.ltd.uk/?kw=floodgate&fl=23371&ci=1618291910&network=s&gclid=CNaE7YaE5bsCFSYHwwodvjcAIQ

I found this after seeing the name on one of their products in the Dumfries video posted by Lon More.

By the way, my interest in 'better than a sandbag' flood defences came after seeing the pictures of Emsworth, where Mr & Mrs Mechta Senior live. Fortunately despite having floods on all sides of them, they have been unscathed (unwashed?) so far.

vulcanised
4th Jan 2014, 16:31
Local councils would probably reject the foam idea on the basis that it gives off toxic fumes when ignited http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif

G-CPTN
4th Jan 2014, 16:32
Wondered whether in light of fact that new Gatwick runway is likely to be built then where would all this run off go ?
He suggested giant reservoir between runway but I pointed out bird problem, but he said covering it avoids that plus in times of weather as at present it can hold lots of flood water to release a week later. New-build housing developments in our village are required to have 'containment' systems for surface water that store the run-off in (underground) large-diameter pipes with controlled outflow into the public sewer system.

This is because the legacy sewers are 'combined' (ie they contain both foul and surface water) and the disposal of the elevated volume that results from storm conditions exceeds the capacity of the transfer system (a pipe under the river that connects to the treatment works).

There isn't a problem coping with the domestic discharges, but when storm water enters the drains and overwhelms the capacity of the system the raw sewage mixture leaks out of the inspection covers.

By restraining the surface water from development sites it prevents the situation from getting any worse (than it is now when we get storm conditions).

Mechta
4th Jan 2014, 16:56
Local councils would probably reject the foam idea on the basis that it gives off toxic fumes when ignited http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif


Not to mention the fear of being sued by the hordes of council tax payers flocking to A&E having tried to cut their piece of council supplied plywood to the size of their door.

vee-tail-1
4th Jan 2014, 20:13
Mechta thanks for the Floodgate link :ok:

Hydromet
4th Jan 2014, 21:07
Or build more rivers

Farmer I know in Shropshire said council came along a couple of years ago and dredged all the ditches to make the water drain away quicker. He and his neighbours just smiled.

Whole point of ditches was to take water from the fields slowly and feed into watercourses slowly.

Water quickly drained from his fields as did everybody elses and just piled up further down river.

Dredging the rivers will help but you need the land to hold the water and release slowly.
About 20 years ago, a colleague was sent to Europe (mainly working in Germany & France) to 're-naturalise' rivers that had been canalised - i.e. the natural bends had been straightened & the banks cleared and smoothed. The channeled rivers had greater capacity and therefore reduced flooding upstream and in their immediate vicinity, but delivered higher flow rates downstream.

Private jet
4th Jan 2014, 21:12
I told you all, move to the fens. A built in flood defence system. What part of that do you not understand or accept? ok, maybe you can't do a big long "clever" post on here about it and that puts you off, you clever things?

racedo
4th Jan 2014, 21:26
Not to mention the fear of being sued by the hordes of council tax payers flocking to A&E having tried to cut their piece of council supplied plywood to the size of their door.

Forget plywood...........plastic that you can expand to size of door

cockney steve
4th Jan 2014, 21:35
I told you all, move to the fens. A built in flood defence system. What part of that do you not understand or accept? ok, maybe you can't do a big long "clever" post on here about it and that puts you off, you clever things?


Cos theFens are populated by web-footed hayseeds and flat as a pancake and the only thing of interest is spuds and tulips......
Well, you did ask!:}


Now, OOP NORTH, we have gritstone hills, moors wi' lots of soakey-uppy Peat and men are Men -and sheep are worried.

Private jet
4th Jan 2014, 21:58
Haha, Yeah the old school "Fennies" ("Fennys"?) are an issue, but most people now are imports (thank f**k) & have to commute to London etc. everyday (poor souls) but still an improvement.

Loose rivets
5th Jan 2014, 02:25
He and his neighbours just smiled.


Aye, and nodding . . . and showing their blackened teeth sucking on a straw. And they were just the council. You should see the villagers when then nod knowingly.:ooh:

G&T ice n slice
5th Jan 2014, 08:21
Really big strong bag larger in 1 dimension than your door.

put empty bag in door.

fill with water until it completely fills the doorspace.

would that work?

OFSO
5th Jan 2014, 08:43
're-naturalise' rivers that had been canalised

I lived on the edge of the Rhine valley for 25 years. At one point in my life I lived a few kms from a beautiful valley winding its way up into the hills past several villages. The stream wandered down at the side of the road, kids played in it, aquatic birds lived there, cows and horses came down to drink from it. In my time there it never flooded. Then the powers-that-be dug it out, put it in a concrete channel and paved it over and went away rubbing their hands and saying "job well done"..

And it was not the only case: during that time most of the local tributaries feeding the River Rhein were channeled: the old willow trees growing at the sides dug up and thrown away, bends straightened, a neat and orderly concrete stream bed inserted and the ducks and geese living there told to "Hau ab" (or p*ss off) and find somewhere else to live.

The results of the water rushing to its new destination and not filtering down through the natural bed: the water table in the valley (wide and flat at that point) dropped so that the local farmers could no longer find any artesian water; historical buildings developed cracks and subsidence as the ground dried out down to 50 metres depth; the Rhine flowed quite a bit faster (it also had been straightened out and told to behave itself) and flooding increased in the many towns along the long valley past Rudesheim up to Bonn. Every autumn when it rained and every spring when the snow melted.

And the Authorities stood around wondering how all of that could have happened.

probes
5th Jan 2014, 08:43
fill with water until it completely fills the doorspace.
have floodwater fill it? :ouch:

G&T ice n slice
5th Jan 2014, 21:57
have floodwater fill it?

hmmmm, yes, I may have been a bit concise there...

I was sort of thinking a big version of a water balloon, or the plasitc bag inside a "box" of wine.

put it in an opening, fill it with water from the tap and it should theoretically mould itself into all the contours of the doorway and provide a pretty good seal. plus it would be as dense as water so wouldn't float.

somehow I don;t think this is actually going to get me "young inventor of the year" and a gazzillion spondulicks

G-CPTN
5th Jan 2014, 23:11
plus it would be as dense as water so wouldn't float.

But only the same density as the surrounding water, whereas sand is much denser and therefore has greater inertia to resist currents.

llondel
5th Jan 2014, 23:53
I told you all, move to the fens.

My house is in a village that has parts dating back 800 years. If you look at the flood maps of the area, it's effectively an island if you were to put a lot of water into the area. The trick is to buy a property in the older parts of such villages, rather than the new build half a mile down the road on the flood plain. When the local area did experience an excess of water (it's interesting to observe water coming up out of manholes under pressure) we were still high and dry.

As for sandbags, I think you need to use them in conjunction with a suitable pump. Properly stacked, they'll resist the water fairly well, and what does leak through the pump can deal with. This does assume you've got a means of powering the pump though.

CelticRambler
6th Jan 2014, 00:14
Once upon a childhood I did Geography in the senior cycle of secondary school and all that OFSO describes was explained to us as "the wrong way" to manage watercourses because ... it increases the risk of flooding. Ever since I've stood on various (metaphorical and real) hills wondering why so many local authorities seem to employ/contract people who obviously missed out on this chapter of watercourse mechanics.

But 'tis nothing compared to the amusement of listening to a bunch of homeowners complain of flooding when their development took the beautifully descriptive name of the site on which the houses were built: Water Meadows. :}

On the Irish news during the week, there they showed some business owners putting those Floodgate barriers in place. The next day they showed the same premises flooded - the water just came up and over the top ... :sad:

A A Gruntpuddock
6th Jan 2014, 01:59
Water doesn't only get in through doorways.

There are all sorts of gaps in the foundations for service pipes; water, gas, electricity, drains as well as airbricks, etc.

Also, the floods will fill up the drains, and once the outside water level is higher than the top of a downstairs toilet seat (for instance) it will start to flow over the top.

Only way to be safe is to build higher than the floods.

If you have to use a flood plain, build houses with the living areas higher, and accept that the lower level will flood. Difficult to make such properties suitable for the aged and infirm though.

visibility3miles
6th Jan 2014, 02:30
IN California, people will spread out huge sheets of plastic over land at risk of sliding away in a mudslide, particularly that uphill of their homes.
------------------
After Hurricane Katrina, the news made mention of the fact that in New Orleans, many people keep an axe in their attic so they can hack their way out through the roof if the rest of the house gets flooded. Bit too much water for my taste.

They also mentioned people moving furniture and valuable items up to the second floor from the ground floor.
------------------
Some communities are encouraging companies to build roof top gardens or keep more landscaping to reduce city runoff.
Rooftop gardens may be beneficial in areas which accumulate a great deal of rain. Storm runoff water can especially overflow sewer systems. The plants can absorb some of the rainwater and limit the runoff from excess water. Rooftop gardening, in turn, has the potential to reduce the occurrences of flooding.
What Are the Advantages of Rooftop Gardening? (http://www.wisegeek.com/what-are-the-advantages-of-rooftop-gardening.htm)

BlankBox
6th Jan 2014, 05:38
http://s1.directupload.net/images/140106/d5w8ncxt.jpg

SawMan
6th Jan 2014, 06:10
Water doesn't only get in through doorways.

There are all sorts of gaps in the foundations for service pipes; water, gas, electricity, drains as well as airbricks, etc.

Also, the floods will fill up the drains, and once the outside water level is higher than the top of a downstairs toilet seat (for instance) it will start to flow over the top.

Only way to be safe is to build higher than the floods.

If you have to use a flood plain, build houses with the living areas higher, and accept that the lower level will flood. Difficult to make such properties suitable for the aged and infirm though.

Almost all true. Sadly, there's no real solution to easily accessing raised structures. Elevators (lifts) are costly and require power which will be absent in a flood, and an appropriate ramp would be overly long if you have space for it in the first place. Some elderly and disabled folks are leaving the New Jersey shore in the US where hurricaine Sandy hit because to rebuild will mean they now have to elevate their house to meet the new building codes. Once again, the only real solution is to not live where you're going to get flooded.

There is one problem which can be addressed though, that of sewage back-up. A "Backflow preventer" (which is just a one-way valve) can be installed on the sewer line before it enters your house and is now being required by building codes in many US areas. My brother had a house part-way up a slight hill. The sewer line got blocked at the bottom and everything from above sought his house to exit. It was two months of living in a hotel with wife and 3 kids crammed in while their house was repaired and made fit for habitation again, and this during a drought! The city (who was responsible for the mess because of poor maintenance) installed back-flow preventers on tall the houses on that street afterward.

Like the new codes requiring raised houses in N.J., it's a bit late to think about it afterward but I guess we should expect no better from our governments anyway since that's what most of them have always been like.

Prevention is always better than mitigation afterward.

Tone
6th Jan 2014, 09:12
Most impressed by the people wandering about in the floods in Ron Mores video. Wonder how they knew that the water pressure had not lifted the odd manhole cover?

Lon More
6th Jan 2014, 09:17
From page 143 (para 6.4) on The Canalisation of the Maas (http://books.google.nl/books?id=UUV_Nyjf0H4C&pg=PA139&lpg=PA139&dq=canalisation+of+the+maas&source=bl&ots=j6zP39HE5x&sig=HDT66dLpcOXWneCcd9o4vg-oyio&hl=nl&sa=X&ei=xXzKUo2OGuWX1AXW3IAo&ved=0CG8Q6AEwBg#v=onepage&q=canalisation%20of%20the%20maas&f=false) might give some idea of how the problem can be tackled. It has made a great difference here, especially impressive because here the boundary between Belgium and the Netherlands is the river so both countries had to agree on the plan.
Fortunately this scene from 1993 hasn't been repeated

http://www.derooijfotografie.nl/wp-content/uploads/2013/05/maas-bij-obbicht-824x550.jpg

OFSO
6th Jan 2014, 10:09
Blank Box, that looks like (but isn't) the old building in the centre of Michelstadt, Germany. Think about these woodframed old buildings is subsidence doesn't bother them. The whole structure just tilts. I've seen a B & W timber framed house at 15 to the h., not a crack in the plaster infll. Course, walking about inside induced some strange feelings requiring a schanaps or twain.

R