Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

John

On Thu, 10 Nov 2005 22:52:42 GMT, "john"
wrote:

Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

It seems a silly idea to build houses near to where rivers flow/ed.

--
Frank Erskine

"john" wrote in message
...

Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

Dredging estuaries is easy, they just take the silt out to the sea and dump
it on an outgoing tide. Upstream it is difficult. And where is the silt
going to go around Northampton? Dredging has to be done regularly, but
walls only once and some maintenance after.

In article ,
john wrote:
Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

Neither is a good solution. Both hurry the water downstream and that makes
flooding worse. The best idea is to trap the water as far upstream as possible
and let it trickle out slowly. River dredging, bank heightening, bank
strengthening, and river straightening are all counter-productive as they all
require future intervention.
Of course trapping the water up stream also requires constant intervention but
that can be done free of charge as long as you get the right workforce* on the
job.

Of course it also means that you cannot build on the floodplain unless you're
building higher than likely future floods.

*Castor fiber - go on look it up! ;-)

--
John Cartmell john@ followed by finnybank.com 0845 006 8822
Qercus magazine FAX +44 (0)8700-519-527 www.finnybank.com
Qercus - the best guide to RISC OS computing

"john" wrote in message
...
Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

Dredging tends to move the flood problem to a point further downstream where
they haven't dredged because they never needed to previously.
The best flood defence is to build 1,000's of new homes on the flood plain
as these are the most effective way to break the force of the water and slow
it down.

bland

In article ,
says...
Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

The only real solution is to avoid building on flood plains, or get used
to houses on stilts and occasionally commuting by boat.

"bland" wrote in message
...

"john" wrote in message
...
Would it help if rivers were dredged? They nust silt up over the years
and then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

Dredging tends to move the flood problem to a point further downstream
where they haven't dredged because they never needed to previously.
The best flood defence is to build 1,000's of new homes on the flood plain
as these are the most effective way to break the force of the water and
slow it down.


I used to go to a bungalow in low lying land where the occupant had
inventively built a 2 foot berm all around the dwelling. It was strange to
drive over the hump into the garden but it kept him dry when things flooded
all around him. for about two weeks. (With a bit of pumping as required from
a deliberate low sump point within the defended area)

On Fri, 11 Nov 2005 08:17:34 +0000 (UTC), "John"
wrote:


| I used to go to a bungalow in low lying land where the occupant had
| inventively built a 2 foot berm all around the dwelling. It was strange to
| drive over the hump into the garden but it kept him dry when things flooded
| all around him. for about two weeks. (With a bit of pumping as required from
| a deliberate low sump point within the defended area)

The Germans have done that massively on the banks of the Rhine. I stayed
on a camp site on the river side of the 8ft high embankment. The
Electrical equipment was 20 ft above the ground.

--
Dave Fawthrop dave hyphenologist co uk
Help make Usenet a better place: English is read downwards,
please don't top post. Trim replies to quote only relevant text.
Check groups.google.com before asking an obvious question.

Rob Morley wrote:

The only real solution is to avoid building on flood plains, or get used
to houses on stilts and occasionally commuting by boat.

They get over that now by building "town houses"

:¬)

funilly enough, on the same subject, the latest development round
Portishead (on the marsh/swamp land) have a new take on Town houses.
To keep houses right up close to the foot path, they build a garage with
no back on it so your drive is now in the back garden !


--
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http://trade-price-supplements.co.uk - TRADE PRICED SUPPLEMENTS for ALL!
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http://gymratz.co.uk/hot-seat.htm - Live web-cam! (sometimes)

""Pet @ www.gymratz.co.uk ;¬)"" wrote in message
k...
Rob Morley wrote:

The only real solution is to avoid building on flood plains, or get used
to houses on stilts and occasionally commuting by boat.


At low river levels you can see all sorts of obstuctions - particularly near
to bridges. When there are floods it is often such stuff - along with trees
that ends up blocking bridges.

On Thu, 10 Nov 2005 22:52:42 GMT, "john"
wrote:

Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

They used to do just that round our way 20 or so years ago.

Now, they don't seem to bother.

sponix

In message , John Cartmell
writes
In article ,
john wrote:
Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

Neither is a good solution. Both hurry the water downstream and that makes
flooding worse. The best idea is to trap the water as far upstream as possible
and let it trickle out slowly. River dredging, bank heightening, bank
strengthening, and river straightening are all counter-productive as they all
require future intervention.

There has been some *learning* within drainage authorities over the past
60 years. Simply moving the water on by canalising merely hastens the
downstream problem. In our case (upper Lea) there are blockable road
bridges which would encourage the flooding of water meadows if
development didn't force clearance at the first hint of a spate. Rubbish
is returned to the river and blocks the next bridge in the sequence.....

Dredging firms up and raises the banks due to the disposal of gravels
and silt. The riparian owner is reluctant to have such material spread
evenly over his field.

What seems to have been learned is that slowing water flow by deepening
leads to silting and a re-cycling of the problem. Pressure from fishing
interests to deepen the water has had to be balanced by artificial
chicanes to keep the silt moving.

Of course trapping the water up stream also requires constant intervention but
that can be done free of charge as long as you get the right workforce* on the
job.

Hmm.. The TV presentation of the current release of European Beavers
implied that they are not destructive and do not build dams but I may
have misheard:-)

Of course it also means that you cannot build on the floodplain unless you're
building higher than likely future floods.

I have never understood why planners are so reluctant to permit
development on valley slopes. I can see that the best land and
availability of water power would make valley bottoms attractive to the
first arrivals which means that development envelopes enclose the area
most likely to flood. Surely development can be made visually attractive
and we can move on from the *green and pleasant land* pretence; until
you drive over the next hill. Hill top developments here tend to be
unattractive cramped social housing because these are the only schemes
able to get planning consent under the exception rules.

regards

--
Tim Lamb

"Dave Fawthrop" wrote in message
...
On Fri, 11 Nov 2005 08:17:34 +0000 (UTC), "John"
wrote:


| I used to go to a bungalow in low lying land where the occupant had
| inventively built a 2 foot berm all around the dwelling. It was strange
to
| drive over the hump into the garden but it kept him dry when things
flooded
| all around him. for about two weeks. (With a bit of pumping as required
from
| a deliberate low sump point within the defended area)

The Germans have done that massively on the banks of the Rhine. I stayed
on a camp site on the river side of the 8ft high embankment. The
Electrical equipment was 20 ft above the ground.

That reminds me when I was in Worth-am-Mein near Frankfurt a few years ago.
The old town hall has permanent records on its side wall of how high the
floods got, going back centuries. The highest was about 12 feet up, and
given the ground was 12 feet up from the normal river, that is a 24 foot
flood. Didn't seem to bother them too much.


bland

In article , Tim Lamb
wrote:
Of course trapping the water up stream also requires constant intervention
but that can be done free of charge as long as you get the right
workforce* on the job.

Hmm.. The TV presentation of the current release of European Beavers
implied that they are not destructive and do not build dams but I may have
misheard:-)

They are not destructive but they do build dams. Their usefulness is in the
dams that hold the water giving it time to soak into the ground and re-appear
on the surface lower down the valley after (or long after) the first rush of a
storm. Rather than destroying great swathes of woodland Castor fiber manage it
to the benefit of both the vegetation and other animals. There really isn't a
downside and their absence has caused many problems for us over the years.

Re-introductions of C. fiber to western Europe have taken place over the years
(from memory since the 50s?) with little or no problem.

My daughter studied the proposals for re-introduction for her MSc and was
*very* sceptical from the start. She is particularly scathing about the mess
made in introduction of European animals in Australia but ended up supporting
the proposed C. fiber project considering it only too little, too late, and
why only Scotland?

--
John Cartmell john@ followed by finnybank.com 0845 006 8822
Qercus magazine FAX +44 (0)8700-519-527 www.finnybank.com
Qercus - the best guide to RISC OS computing

"john" wrote:

Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

No, you might go too deep and pull the plug out *
[*] it actually happened on the Chesterfield canal a few years ago



--

john wrote:
Would it help if rivers were dredged? They nust silt up over the
years and then when there is a high rainfall they don't have the
capacity. The solution always seems to be based around raising the
banks.

John

Its more cost effective to dredge the rivers.

--
Sir Benjamin Middlethwaite

In article ,
Matt wrote:

No, you might go too deep and pull the plug out *

[*] it actually happened on the Chesterfield canal a few years ago

.........and on the Gloucester-Sharpness canal.

--
Tony Williams.

In an earlier contribution to this discussion,
Owain wrote:

Rob Morley wrote:
The only real solution is to avoid building on flood plains, or get
used to houses on stilts and occasionally commuting by boat.

Some people are putting polystyrene rafts under their holiday
caravans, so they float in the event of flooding.

Owain

I hope they've anchors on, as well.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In article , PeTe33
@gymratz.co.uk says...
Rob Morley wrote:

The only real solution is to avoid building on flood plains, or get used
to houses on stilts and occasionally commuting by boat.

They get over that now by building "town houses"

:¬)

I hadn't thought of them like that before, but you're right.

funilly enough, on the same subject, the latest development round
Portishead (on the marsh/swamp land) have a new take on Town houses.
To keep houses right up close to the foot path, they build a garage with
no back on it so your drive is now in the back garden !

They're getting closer to the stilts model. :-)

In article , owain47125
@stirlingcity.coo.uk says...
Rob Morley wrote:
The only real solution is to avoid building on flood plains, or get used
to houses on stilts and occasionally commuting by boat.

Some people are putting polystyrene rafts under their holiday caravans,
so they float in the event of flodding.

I wonder where they will end up :-)

On Fri, 11 Nov 2005 19:48:30 UTC, Rob Morley
wrote:

In article , owain47125
@stirlingcity.coo.uk says...
Rob Morley wrote:
The only real solution is to avoid building on flood plains, or get used
to houses on stilts and occasionally commuting by boat.

Some people are putting polystyrene rafts under their holiday caravans,
so they float in the event of flodding.

I wonder where they will end up :-)

Flodden?

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
Avenue Supplies, http://avenuesupplies.co.uk

"Bob Eager" wrote in message
...
On Fri, 11 Nov 2005 19:48:30 UTC, Rob Morley
wrote:

In article , owain47125
@stirlingcity.coo.uk says...
Rob Morley wrote:
The only real solution is to avoid building on flood plains, or get
used
to houses on stilts and occasionally commuting by boat.

Some people are putting polystyrene rafts under their holiday caravans,
so they float in the event of flodding.

I wonder where they will end up :-)

Flodden?

Well it is a battle

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "john"
saying something like:

Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

The problem is caused by too much land drainage.
--
Dave
GS850x2 SE6a
I demand nothing of you except that you amuse me.

On Thu, 10 Nov 2005 22:52:42 GMT, "john"
wrote:

Would it help if rivers were dredged? They nust silt up over the years and
then when there is a high rainfall they don't have the capacity. The
solution always seems to be based around raising the banks.

John


You have entered a "dark zone". The current thinking is that the best
thing to do is to leave the rivers alone, and respect them. In the old
days we used to straighten and deepen rivers, which makes the water
flow fatser, and the nautral erosion increase, and more work be
required.

Have a read up on the Missiippi, and see just how badly the Americans
screwed a river up.

At the end of the day, if you build a city below water level next to a
major river its gonna flood from time to time.

Rick