News0 min ago
Pumping Water From Flooded Villages
A number of times over the past month we have seen on the news that the fire brigade is pumping massive amounts of water from certain areas so that the flood waters might recede a little quicker.
My question is where is it pumped to?
Are they just moving it from the floodsite to the nearest river? Isn't that river at flooding point too? If so, will it not affect the next town/village just down river?
Am I being really thick here but I have asked two relatives and they aren't sure either.
My question is where is it pumped to?
Are they just moving it from the floodsite to the nearest river? Isn't that river at flooding point too? If so, will it not affect the next town/village just down river?
Am I being really thick here but I have asked two relatives and they aren't sure either.
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This is only one example and the video partly answers your query, but not all situations will be the same.
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I stand to be corrected on this but I thought I heard that there are places where the river is ABOVE the level of the surrounding fields, the water being held in the river by built-up banks in normal circumstances. The river has overflowed into the fields which are saturated, so the water can't get away. Meanwhile the water level in the river has dropped, so now they can pump the water from the fields UP into the river, from where it can now drain away.
i THINK the tidal argument only applies to areas nearer to the sea - again, I stand to be corrected.
i THINK the tidal argument only applies to areas nearer to the sea - again, I stand to be corrected.
As I understand it the flooding is mainly the result of excessive rain on waterlogged land , not from overflowing rivers. So it makes sense to pump the water from the land into a river as long as it is flowing and has the capacity.
There is also the point that protecting one high populated area at the possible expense of another sparcely populated one isn't necessary such a bad thing. It's a choice governments have to take throughout the world.
All our rivers have flood gates that allow excess water to deliberately flood lower lying water meadows, and if people choose to live on or near vulnerable areas they know the risks. They also know it doesn't make economic sense to spend tens of millions on protecting a few hundreds of people in isolated villages.
There is also the point that protecting one high populated area at the possible expense of another sparcely populated one isn't necessary such a bad thing. It's a choice governments have to take throughout the world.
All our rivers have flood gates that allow excess water to deliberately flood lower lying water meadows, and if people choose to live on or near vulnerable areas they know the risks. They also know it doesn't make economic sense to spend tens of millions on protecting a few hundreds of people in isolated villages.
I'm afraid the government will somehow have to find the money for flood defences in the future as the changing weather patterns suggest that this flooding situation will be a permanent one in the UK. I would also suggest that future houses in vulnerable areas should be built on stilts to help combat the situation & I think that the second family car will be a boat.
WR.
WR.
If you hear people referring to 'the Monbiot article', they probably mean this one: -
http://
Or there's a blog piece, in much the same vein: -
http://
(A good selection of reference material in that one).
I recall a piece of film on the news, showing how an inland (non-tidal?) stretch of the Yangtze river sits several metres above the plain, behind earth ramparts. When these break, the flood covers a huge area. (That might have been what the news report was about, in fact).
http://
Or there's a blog piece, in much the same vein: -
http://
(A good selection of reference material in that one).
I recall a piece of film on the news, showing how an inland (non-tidal?) stretch of the Yangtze river sits several metres above the plain, behind earth ramparts. When these break, the flood covers a huge area. (That might have been what the news report was about, in fact).
Its worth pointing out that the Somerset levels are not your typical flood plain. The area was drained in Medieval times in the same way that most of the modern Netherlands were. Before it was drained it was just a swamp. Since then it has been very productive farming land, with a sizable resident population that relies on it.
People have lived here for hundreds of years. Its just not good enough that the Environment Agency should have stopped dredging and managing these areas properly. I was listening the Eavis the other day and he was scathing about what has gone on. Its about time that we started listening to him and the other locals, instead of hapless Government Agencies.
People have lived here for hundreds of years. Its just not good enough that the Environment Agency should have stopped dredging and managing these areas properly. I was listening the Eavis the other day and he was scathing about what has gone on. Its about time that we started listening to him and the other locals, instead of hapless Government Agencies.
Interestingly, EDDIE, it's almost the other way around.
Monbiot is writing about rivers in general. The locals in Somerset are arguing that the agricultural land is *man-made*, the rivers which drain it are also *man-made* and have been, traditionally, maintained - i.e. dredged.
Evironmentalism is a recent movement and pressure was applied to "save" (or perhaps create?) river-edge habitat and dredging was brought to a halt.
Clock ticks for a number of years, silt builds up and one bad winter ends up in a major flood event.
In short: -
river straightening and dredging nationwide: bad idea
river straightening and dredging on the levels: good idea
(even better if landowners do it at their own expense, not the taxpayers)
Monbiot is writing about rivers in general. The locals in Somerset are arguing that the agricultural land is *man-made*, the rivers which drain it are also *man-made* and have been, traditionally, maintained - i.e. dredged.
Evironmentalism is a recent movement and pressure was applied to "save" (or perhaps create?) river-edge habitat and dredging was brought to a halt.
Clock ticks for a number of years, silt builds up and one bad winter ends up in a major flood event.
In short: -
river straightening and dredging nationwide: bad idea
river straightening and dredging on the levels: good idea
(even better if landowners do it at their own expense, not the taxpayers)
Having been to skool there
the levels in the ditches/canals were below ground level.
and if you wanna drain a marsh that is what you do.
I can see that if you dont dredge a draining canal - then it wont work
None of us could understand the idea of canals up t' North being lined with
clay to prevent the water leaking out since the whole point of a canal in Zummerset is for the water to leak in ....
the levels in the ditches/canals were below ground level.
and if you wanna drain a marsh that is what you do.
I can see that if you dont dredge a draining canal - then it wont work
None of us could understand the idea of canals up t' North being lined with
clay to prevent the water leaking out since the whole point of a canal in Zummerset is for the water to leak in ....
Can't we take advantage of our EU membership and request aid from our Dutch neighbours, after all they have many years of expertises in such matters?
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I only learned relatively recently (possibly a Time Team special) that large tracts of Holland were once roughly at sea level (tidal saltmarsh/swamp) and that all those windmills weren't there to grind flour but to pump out water. So much water that the soil itself has shrunk to a huge extent and that's how they end up with farmland several metres below sea level.
Similar story for large parts of Lincolnshire and, as mentioned, Somerset.
The sea wall and sluice gate system are an integral part of the land drainage design - what with the elvation of the drainage channel being so close to mean seal level as to be an unfavourable gradient at spring tide (or even at routine high tides).
Thinking about it, you'd think that a silt layer, elevating the channel and increasing the downward gradient to the sea would help speed up flow. However this does mean progressive increase in how high water has to be lifted by pumps at the upstream end - meaning more energy costs as the years go by.
Dredging to increase carrying capacity of the drains? You could do a simple volume calculation to work out how one kilometre of dredge cut equates to square km of knee-depth water but I doubt the results would be impressive.
Similar story for large parts of Lincolnshire and, as mentioned, Somerset.
The sea wall and sluice gate system are an integral part of the land drainage design - what with the elvation of the drainage channel being so close to mean seal level as to be an unfavourable gradient at spring tide (or even at routine high tides).
Thinking about it, you'd think that a silt layer, elevating the channel and increasing the downward gradient to the sea would help speed up flow. However this does mean progressive increase in how high water has to be lifted by pumps at the upstream end - meaning more energy costs as the years go by.
Dredging to increase carrying capacity of the drains? You could do a simple volume calculation to work out how one kilometre of dredge cut equates to square km of knee-depth water but I doubt the results would be impressive.
Everyone forgets that rivers flow Hypo
so even with a modest fall - you can get huge flows
and it is not the volume of the river that is the deciding factor
A fall of a metre without friction give a speed at the end ( root -2 - g - h )
of 4 ms-1- so even with a cross section of 20 m2 - that is 80 t s -1
so even with a modest fall - you can get huge flows
and it is not the volume of the river that is the deciding factor
A fall of a metre without friction give a speed at the end ( root -2 - g - h )
of 4 ms-1- so even with a cross section of 20 m2 - that is 80 t s -1
Ok, quick calc
For every kilometre of dredge 10m wide by 1m deep.. (10,000 m^3)
you can empty 141.4 square metres of water 50 cm deep
If the river flows faster than 1 km/hr then you can multiply up accordingly and you have 6 hours or so before the tide begins to reverse.
(10m dredge width would probably take several runs with a dredger. I'm hoping someone knowledgeable will chip in with some facts and figures).
For every kilometre of dredge 10m wide by 1m deep.. (10,000 m^3)
you can empty 141.4 square metres of water 50 cm deep
If the river flows faster than 1 km/hr then you can multiply up accordingly and you have 6 hours or so before the tide begins to reverse.
(10m dredge width would probably take several runs with a dredger. I'm hoping someone knowledgeable will chip in with some facts and figures).
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