dredging rivers

[station tug]

looking at the news and its been said that dredging the rivers is the answer to stopping the floods....what do you think??

[Naughty Cal]

No it isn't.

[mark99]

looking at the news and its been said that dredging the rivers is the answer to stopping the floods....what do you think??

 

There is a school of thought suggesting uplands should be made to take more water (reduction of sheep and replanting with trees, shrubs) not dredging. This will save the quick rush of water which dredging won't fix.

 

It (dredging) is like treating the symptoms and not curing the issue.

Edited February 8, 2014 by mark99

[Naughty Cal]

People seem to think dredging is a quick fix to flooding when it isn't.

 

All the dredging in the uk won't sort out flooding like we are experiencing right now.

[Alan de Enfield]

Dregding would be of considerable benefit as a deeper channel is going to help take more water away quicker.

 

At the same pressure a 4" pipe will carry more water than a 2" pipe.

 

Not putting huge swathes of concrete down would help - all the water that falls on cities goes down the drains and into the rivers, in previous times there would have been soil,trees and fields which would have absorbed the water.

 

Flooding is a man made 'disaster' and inevitable in our modern society - the best we can do is 'manage the risk' and be prepared to spend to achieve it

[furnessvale]

Dregding would be of considerable benefit as a deeper channel is going to help take more water away quicker.

 

At the same pressure a 4" pipe will carry more water than a 2" pipe.

 

Not putting huge swathes of concrete down would help - all the water that falls on cities goes down the drains and into the rivers, in previous times there would have been soil,trees and fields which would have absorbed the water.

 

Flooding is a man made 'disaster' and inevitable in our modern society - the best we can do is 'manage the risk' and be prepared to spend to achieve it

Large areas of the Levels are below high tide level. Man took this land from the sea so man should not be surprised when the sea wants it back again.

 

George ex nb Alton retired

[peterboat]

Yes I agree when we flooded all those years ago the water was moving very swiftly until the tide cane in and then it was like someone had put the bung in the hole! The water stopped and then the water went everywhere, Keith and I earlier on had been up the moorings and released as many ropes as we were able but as the water went up and the river joined the the canal and we went up 3 foot above the towpath I just felt sorry for all those people in houses that couldnt float. All the dredging in the world cant stop the tide coming in, in fact it would help the tide!!

 

Peter

[David Schweizer]

For years the road at Limpley Stoke, near where I live, used to flood almost every year, often making it impassable. They dredged the River Frome some years ago and the flooding is now a memory. Even with the rain we have had over the past couple of momnths it has not flooded. Not conclusive evidence, but it demostrates that sometimes dredging maintainance can prevent flooding.

Edited February 8, 2014 by David Schweizer

[magpie patrick]

People seem to think dredging is a quick fix to flooding when it isn't.

 

All the dredging in the uk won't sort out flooding like we are experiencing right now.

 

In the case of the Somerset levels I beg to differ: whilst it wouldn't have completely solved the problem I have seen the Parret and the Tone shrink over the last twenty years, with all sorts of reasons given for not dredging them. The wildlife argument was demolished some time ago as the banks of these rivers are very poor due to the particular character of the tide and the river.

 

The comment has been made that it used to take five days of heavy rain for the rivers to become "bank full" now it tales 24 hours, lack of dredging is in part responsible for this. The failure to clear the rhynes also hasn't helped, as the land hasn't been allowed to dry out between winters, despite a dry summer (at least in these parts) last year

[Naughty Cal]

Modern developments have to retain water on site and release it at an agreed rate by way of a flow control device.

 

The extra water is stored on site either underground in tanks or oversized pipes or increasingly above ground in ponds and basins.

 

Flooding isn't a man made event. It is a natural event which has occurred since long before man existed. Same with global warming. It's nothing new!

[magpie patrick]

Large areas of the Levels are below high tide level. Man took this land from the sea so man should not be surprised when the sea wants it back again.

 

George ex nb Alton retired

 

True, but Man started taking the Somerset levels from the Sea in Roman times, it's hardly a modern innovation

Modern developments have to retain water on site and release it at an agreed rate by way of a flow control device.

 

The extra water is stored on site either underground in tanks or oversized pipes or increasingly above ground in ponds and basins.

 

Flooding isn't a man made event. It is a natural event which has occurred since long before man existed. Same with global warming. It's nothing new!

But systematically not dredging the Parret and the Tone is new...

[David Schweizer]

 

In the case of the Somerset levels I beg to differ: whilst it wouldn't have completely solved the problem I have seen the Parret and the Tone shrink over the last twenty years, with all sorts of reasons given for not dredging them. The wildlife argument was demolished some time ago as the banks of these rivers are very poor due to the particular character of the tide and the river.

 

The comment has been made that it used to take five days of heavy rain for the rivers to become "bank full" now it tales 24 hours, lack of dredging is in part responsible for this. The failure to clear the rhynes also hasn't helped, as the land hasn't been allowed to dry out between winters, despite a dry summer (at least in these parts) last year

 

Well said Patrick

 

The difference between yourself and Rachel is that you live and work in Somerset , she lives up north and has probably never even visited the Somerset levels, let alone witnessed the gradual decline in maintenance, which has undoubtably contributed to the current problem.

 

Like you, I know the levels quite well, and more importantly have met many of the farmers who live and work there. I have witnessed a decline in the dredging which has caused quite significant flooding in even comparatively low rainfall winters. the farmers know the risk, grow crops that suit the terrain and move animals off the lower levels onto higher land each winter as a matter of routine,

 

What most people do not seem to appreciate is that the levels are not all low lying land , there are quite large areas of higher land within them, where the Farm buildings and Villages are located. the problem is that these "safe" areas have been overcome by the water because it cannot escape quickly enough, Contrary to popular myth, there never have been vast forests on the levels to absorb water, nor has there been very much developent preventing absorbtion and encouraging excessive run off

 

The problem has undoubtably been exagerated by the recent very heavy rain, but the lack of Dredging over more than twenty years has converted what would have been a "bad" winter into a disaterous one.

Edited February 8, 2014 by David Schweizer

[kris88]

they seem to manage in holland quite well, it gets very similar weather to here.

Its possibly sensible levels of invesment that sorts them out.

Edited February 8, 2014 by kris88

[Chop!]

They didn't fair well in the Netherlands until they instigated a huge water management system

[LEO]

People seem to think dredging is a quick fix to flooding when it isn't.

 

All the dredging in the uk won't sort out flooding like we are experiencing right now.

 

Probably the best outlook on this situation so far, it's not just dredging rivers but also clearing and dredging ditches, all these works are neglected until needed and then a Knee jerk reaction is expected to produce results.

 

L.

[Bee]

Dredging makes no difference to the capacity of a river. you can dig endless holes in the river bed and the surface level stays the same. Start at the top of the river and start to dredge it, carry on all the way down and you end up having to lower the sea bed. You need to increase the gradient - not possible, increase the width, impractical or contain it in higher banks, all the way down. A 4" pipe will carry more than a 2" pipe but a river is a trough, you increase its capacity by widening it, its the `unused` depth of the bank between the water surface and the top of the bank that matters and dredging doesn`t lower the surface level. Somerset levels? pumps are the only way, why has Holland got windmills? its not to mill flour, its to pump water uphill.

[kris88]

 

 

They didn't fair well in the Netherlands until they instigated a huge water management system

Exactly i believe there last really big flood was in 1953

[magictime]

 

There is a school of thought suggesting uplands should be made to take more water (reduction of sheep and replanting with trees, shrubs) not dredging. This will save the quick rush of water which dredging won't fix.

 

It (dredging) is like treating the symptoms and not curing the issue.

 

Indeed. This article argues that the removal of 'unwanted vegetation' on farmland in order to be eligible for farming subsidies has had perverse outcomes. Perhaps not directly relevant to the floods in Somerset right now , but very interesting in terms of the wider issue:

 

http://www.theguardian.com/commentisfree/2014/jan/13/flooding-public-spending-britain-europe-policies-homes

Edited February 8, 2014 by magictime

[Bunny]

We spent 20 years on the levels and have farmer friends on the levels. My parents owned The Langport Arms , my husband was the local butcher. and later we lived near Bridgwater, our daughters godparents , both sets are somerset level farmers , now marooned , can't even get out by tractor, one has just bought a small hover craft , yet to see how that pans out . Langport was originally called 'Longport' and the sailing ships used to sail up the Parrott from Bridgwater , they used to unload in Langport and the cargo went further up the Parrott to Long Load. Up until 10 years ago the drainage board was responsible for the welfare of the rivers and rynes (rynes are anything from 3ft to 20ft wide 4ft to 15ft deep, cut into the sedge peat and generally running straight)think of Holland , because it was the Dutch that improved these waterways. The boards were abolished ( I think under Baroness Young , could be wrong about which labour peer ) the only drainage board to survive is The Broads, and the dredging stopped immediately . Locals and farmers have been protesting since day one and have not ignored. This is a community that have handed farms down from generation to generation, worked the levels and managed the water. The houses and villages that are now being flooded are hundreds of years old , not new flood plane builds. People on the levels are used to flooding but not on this scale. Yes there would have been more flooding than usual, but no where near this scale, and they would have got on with it , these people don't bleat, they get on with it they are farmers that what they do ,help one another, just like I hope we boaters would . The R.S.P.B bought a big parcel of land on the levels ( about the same time as dredging stopped ) to in courage wading birds ( the first place visited by Mr Smith yesterday). The levels are peat based. Down on the moors if you jump up and down it moves with you , springy and spongy, as in soaks up water and (don't know who said it ) but it has been kept wet in the summer now , not allowed to dry out ( for the birds) . So would dredging help , too bloody right, talk to the people who have worked the levels for generations . Bunny.

[Nightwatch]

Locally to me here, there is a village,Hambledon, that is presently flooded with lovely clear water running along the streets. Sewage is redirected through newly installed surface pipes, temp measure.

 

The water has drained of the Downs, as it's meant to do and has always done. The difference being that the ditched that ran alongside the roads for hundreds of years were filled in to accommodate all the military vehicles for the 'D' day landings in 1944. What the locals are calling for and have been now for some years is a 2 foot or larger pipe be installed down and under the roads to take the water away in such instances.

 

You can only stop water to an extent, but you can manage it and it's dispersement.

 

Martyn

[David Schweizer]

Dredging makes no difference to the capacity of a river. you can dig endless holes in the river bed and the surface level stays the same. Start at the top of the river and start to dredge it, carry on all the way down and you end up having to lower the sea bed. You need to increase the gradient - not possible, increase the width, impractical or contain it in higher banks, all the way down. A 4" pipe will carry more than a 2" pipe but a river is a trough, you increase its capacity by widening it, its the `unused` depth of the bank between the water surface and the top of the bank that matters and dredging doesn`t lower the surface level. Somerset levels? pumps are the only way, why has Holland got windmills? its not to mill flour, its to pump water uphill.

 

Despite suggestions from some people, the Somerset levels are not below sea level, the average height is about 25ft above mean sea level with some lower areas down to 12ft above sea level. Water flows down hill, so until the flooded area of the levels exceeds that of the sea and until the sea level increases by at least 12 feet, a larger drainage ditch will carry more water downhill into the sea and consequently minimise excessive flooding. The Monks in the Middle Ages knew that and since then two more drainage channels have been dug, until recently they were routinely dredged. It is only since the Environment Agency ceased any significant dredging that the problem has gradually worsened, and whilst the levels will always incur some flooding , it could easily be reduced to managable proportions.

[nebulae]

Farmers in this area(upland Wales)are receiving 50% grants to concrete yards.The idea is to prevent polutants reaching watercourses!This is well known to be a load of coblers in this area. It is a good way of getting the taxpayer to pay for improving farm businesses As a lot of water which ends up in lowlands starts here,this is probably not a good plan. However,local pre mix concrete companies are flat out.

[Mike Todd]

Dregding would be of considerable benefit as a deeper channel is going to help take more water away quicker.

 

At the same pressure a 4" pipe will carry more water than a 2" pipe.

 

Not putting huge swathes of concrete down would help - all the water that falls on cities goes down the drains and into the rivers, in previous times there would have been soil,trees and fields which would have absorbed the water.

 

Flooding is a man made 'disaster' and inevitable in our modern society - the best we can do is 'manage the risk' and be prepared to spend to achieve it

There some very interesting documents from EA which set out in detail the problems over dredging, which are much more complex than the cost. It is definitely not just a matter of seeing a river as a 2" pipe.

 

OTOH, they also confirm that some of the cause is long term land management - or lack of it.

[Paul's Nulife4-2]

Hi gang,

I have been on the River Arun for a bit now, Apparently it's the 2nd fastest flowing river in Britain & the tidal difference can be some 6mtr pluss.

There is a 'Friendly' banter between members of the Littlehampton Marina (where I am) that has a small but effective portable onsite dredger that is in use 3 days a week,yep every week & Arun yacht club some 1000yds down river, who have just spent a huge amount of money on there 3 to 5 yearly mass dredging program on 'The swapping of mud'

Like a lot of rivers,we have a Bar at the entrance that boats has had intimate relations with in the past (yep mine as well) due to it's constant swelling,ad they do & Flooding onto roads,paths,car park and the Arun View pub is certainly common especially in the time I've been here,and the weather we have experienced over the last 18mth. So what are they doing about it. well a Massive amount is currently being spent 'Siding' the river, Inserting pile driven mettle sheets, narrowing the river in the process, & are half way through Building houses on a flood plane some 60yrds from the waters edge !.

That's going to help then !.

Edited February 8, 2014 by Paul's Nulife4-2

[b0atman]

Its all down to bad land management infilling dykes and ditches removing Hedgerows narrowing water courses .Building on flood plains.