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mac
Joined: 07 Mar 1999
Posts: 17749
Location: Berkeley, California
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 Posted: Wed Dec 30, 2015 1:27 pm Post subject: Flooding in Great Britain, climate change and sea level rise |
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Given the flooding in Great Britain, and the fact that Storm Frank is now battering the island and has washed away Balmoral Bridge, I thought this subject merited a separate trend. The scientific question of the relationship between climate change and these storms remains unresolved, but I would note reports that Storm Frank was preceded by a massive amount of warm air--which increases the ability of the storm to carry water. At one level the physics is very elementary. Warm water provides the energy for storm intensity, and the oceans have heated up substantially over the last 15 years while skeptics claimed that there was a hiatus in global warming. More heat means more energy in storms and warmer storms mean more water in the rainfall.
I had asked GT for a more substantive response on the underlying causes before he reached the conclusion that dredging was the only possible solution, and that somebody (presumably in his mind the incompetent but not underfunded government) should have done something. It is safe to say that I was underwhelmed by his answer.
It is easy enough to poke around the web on the issue of flooding and find simplistic answers that match GT's conclusion. But behind nearly every problem of this sort lies a set of both technical and governance issues that make solutions somewhat more elusive. Typical of the "leap to a conclusion" screeds is this, found at https://notalotofpeopleknowthat.wordpress.com/2015/12/26/what-the-authorities-wont-tell-you-about-the-floods/
| Quote: | Last century the obligation to dredge out the rivers was transferred to local river boards, consisting of farmers and landowners who knew the area and its characteristics, and who had statutory responsibilities to prevent or minimise flooding. But all this changed with the creation of the Environment Agency in 1997 and when we adoptedthe European Water Framework Directive in 2000.
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The source for this quote is Phillip Walling, who blames the problem on conservationists, and seems to hew to a climate skeptic if not denier perspective.
I continue to think that there is a responsibility to develop some understanding of the underlying problems before you simply slag a perceived villain, even if that perceived villain is the government. This is particularly true with flood control, where a mind set of denial is prevalent in the political arena, where politicians, faced with the actual costs of dealing with flood hazard, put on a posture of magical thinking, while hoping desperately that the floods don't occur while they are in office. Those floods are a result of flawed engineering thinking of the mid 20th century, and development in the flood plain that has flooded repeatedly over the past 100 years. Often the governance problem of approving development where the local councils should not, is compounded by the inability of the local flood control organization to do its job.
Most of these problems seem to apply along the Ouse, or as it is more commonly called in England, the Great Ouse. The river and marshes of the lower watershed have been dramatically altered to allow navigation, agriculture, and other forms of development. I am not sure, but I would suspect that the navigational value of the river has diminished over time as containerization and land transport have become more prevalent, so that the navigational imperative to dredge--and funding base--has also been diminished.
GT apparently failed to find the most recent official look at flooding risk and management on the lower Ouse, found at http://www.eastcambs.gov.uk/sites/default/files/agendas/sd101109ag_J217Appendix.pdf and titled “The Great Ouse Tidal River Strategy Draft for consultation" September 2009
I found this bit of analysis particularly interesting:
| Quote: | The Ouse Washes are the largest area of frequently flooded grazing marsh in the UK. This makes them attractive to certain bird species (including breeding waders and overwintering birds). It is therefore now an area of international conservation importance and is a designated Special Protection Area.
Over the past 75 years river bed levels in the Great Ouse Tidal River have risen. Bed levels rise during droughts as silt is drawn in from the sea, on the tide, and settles in the Great Ouse Tidal River – primarily downstream of Denver Sluice. High river flows, following periods of drought, scour the majority of this silt back out to sea, but sometimes not all of it is removed. In addition, as a result of the construction of the Great Ouse Flood Protection Scheme 50 years ago, high freshwater flows in the Ely Ouse are now routed
down the Flood Relief Channel instead of through The Ouse Washes in flood
Denver Sluice. This has brought major flood risk benefits for the South Level but it has been achieved at the expense of reduced ‘flushing’ flows in the Great Ouse Tidal River and this in turn has led to higher silt levels in the Tidal River. These high bed levels have a negative impact on the drainage of the Ouse Washes as bed levels are often too high to allow water to drain by gravity into the river. As a result there has been increased flooding on the Ouse Washes for longer periods and to greater depths. High river bed levels and increased flooding on the Ouse Washes create a number of issues:
• high bed levels can impede navigation;
• increased flooding harms habitat suitable for many of the rare birds which visit the site;
• it affects landowners who use the Ouse Washes as grazing marsh;
• users of Welney Road, which crosses the Ouse Washes, must take a 30-mile detour;
• as bed levels continue to rise in the future, the standard of protection provided by the South Level Barrier Bank may reduce;
• anticipated future sea level rise will make the problem of managing silt levels in the Great Ouse Tidal River increasingly difficult in future decades. |
Those improvements date back to 1650, and clearly sea level has risen since that time.
That study goes on to evaluate dredging of the river, and concludes:
| Quote: | This would involve dredging a huge amount of silt – equivalent to the
volume of ten football pitches to a depth of the goal posts. The costs of this
are prohibitive. In addition, there is a chance that silt levels could return to
the previous state within four to six months. |
Since the source of the silt is tidal waters, and the very flat nature of the Ouse washes make them well suited to settle silt, it seems that the idea of dredging the Ouse is not as much of a no-brainer as many would think.
There are huge challenges for flood control as sea level rise accelerates. Some interests want to retreat entirely from flood prone areas, whether those are vulnerable to coastal flooding or riverine flooding. Others want the "government" to step in and fix things. On the technical side, the rapidly changing climate that those who actually work in the field are seeing makes it very difficult to develop the technical underpinning of what storms and sea levels we should design to. The climate of the last twenty years is very different than the climate of the previous 100 years, and hydrology is based on developing enough data about storms to be able to forecast with some level of confidence a future flood, whether it be a 1 in 100 or 1 in 500 year storm. We have no confidence in how rapidly sea level is rising, or enough data to project what even a twenty year storm might be.
Flood control in England now seems to be provided by the Environmental Agency, but that has seen change over the last decade. It is an open question whether, in any country, locals should rely on the potentially greater fiscal resources of the Federal government in order to solve issues like flood control. It may well be that the Federal government in England has the engineering expertise to be able to do the necessary engineering. It may also be true that the Federal government is unresponsive, or underfunded.
Those who would simply do away with governmental agencies without understanding what they do, why they were created, or what problems would remain if they were eliminated, remain loud voices in political debate. Those voices are frequently unconcerned with the facts of the matter, but proceed from an assumption that all government is bad. In California, those voices have made funding for flood control nearly impossible, and rising sea level will mean that more and more property is vulnerable to flooding. |
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isobars
Joined: 12 Dec 1999
Posts: 20935
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| Posted: Wed Dec 30, 2015 2:01 pm Post subject: |
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I'm not going to read anything mac wrote, because it's a foregone conclusion that it's all about AGW deniers and his own denial of the science and data regarding GW. I'm thus pretty sure that just the first click on my first keywords will contradict his latest falling skies rant. He went to kollij; can't he understand that the gravest single threat of AGWA is to his country's and the world's economy, as we piss away scores of trillions of dollars just to appease a primarily political movement to redistribute the world's ... hell, let's get real .. the UNITED STATES' ... wealth to the third world and Al Gore ... and, oh yes, maybe to curtail a hypothetical GW of 0.306 degrees F?
Give it a GD rest, dude, and devote some of your outrage to the 18 identified and bigger problems we can actually, mostly SOLVE, in THIS decade or even the next couple of years, for hundreds of millions or a few billion.
From UCSB at http://scienceline.ucsb.edu/getkey.php?key=922 :
How do ocean currents contribute to the change in climate?
Answer 1:
First off, certain famous ocean currents have well-known effects on climate. Consider the Gulf Stream. The climate in Northwestern Europe (the UK especially) is much more mild than it is directly across the Atlantic in Canada and the Northeastern US. There can be up to a 30-40 degree (Fahrenheit) air temperature difference in January between these two areas. The Atlantic Ocean near Canada is locked in ice in winter but the Atlantic Ocean near England is not. It is thought that the huge temperature difference is due to the Gulf Stream, one of the strongest currents in the ocean, and one of the best studied. (Ben Franklin was one of the first people to map this current. You can check out information on Gulf stream History.)
The Gulf Stream brings warm water from the Carribean and Florida north, along the coast of the US, and then east across the Atlantic to Europe. Because it takes a right-hand turn somewhere around North Carolina, the warming effect of its waters misses the Northeast US and Canada, but does reach England and Ireland. Take a look at some maps of the The Gulf stream and maps.
Wheither or not you think that the relatively mild climate in England, Scotland, Wales, Ireland and Northern Ireland is due to the direct effect of the warm water in the Gulf Stream, or to the indirect effect of The Great Ocean Conveyor Belt ("thermohaline circulation"), of which the Gulf Stream is a part, either way the warming is partly caused by ocean currents. If the Gulf stream was to slow down considerably (as it has in the past), then winters in Europe would become very cold. The last time this happened, from 1450-1900, it was called The Little Ice Age.
There is some concern that current global warming caused by rising carbon dioxide concentrations will cause the polar ice cap to melt and slow down the Great Ocean Conveyor Belt, thus slowing down the Gulf Stream and sparking a cooling event in Western Europe. This is the (tiny bit of) science behind the movie "The Day After Tomorrow". Many scientists think this is unlikely, but recent research shown that past ice ages have been linked to slow downs in the Great Ocean Conveyor Belt. Check out Abrupt Climate Change.
The Gulf Stream is just one example of how ocean circulation affects climate. It is a more complicated story. Winds are an important force driving ocean currents. Winds, in turn, are partly driven by differences in heat from one part of the globe to the next. As global warming affects the global heat budget, it will alter the strength and direction of winds, which will alter the strength and direction of the major ocean currents. We already see evidence for changes in ocean circulation due to global warming, but I don't think anyone knows enough about the complex interaction of winds, currents and the global heat balance to predict what will happen as more and more warming occurs. As ocean currents change (and they will), not only will climate change, but marine ecosystems will change as well, with potentially dramatic effects on all ocean life, as well as on the human food supply. (More than 1 billion people rely on fish as their primary source of protein.)
Answer 2:
The contribution of the ocean currents to the climate exists, and it also works in the opposite direction. I mean, the climate also contributes to ocean currents. Ocean waters are constantly on the move. How they move influences climate and living conditions for plants and animals, even on land.
Currents flow in complex patterns affected by wind, the water's salinity and heat content, bottom topography, and the earth's rotation. Surface water movement takes place in the form of currents. Currents move ocean water horizontally at the ocean's surface. Surface currents are driven mainly by the wind. Other forces such as the Coriolis effect and the location of landmasses do affect surface current patterns. The Coriolis Effect explains how the earth's spin causes the wind to curve. The wind in the northern hemisphere curves to the right and the wind in the southern hemisphere curves to the left.
In fact, huge circular patterns called current gyres can be seen when looking at the world's ocean currents. From the equator to middle latitudes, the circular motion is clockwise in the Northern Hemisphere and counterclockwise in the Southern hemisphere. Near the poles of the Earth, there is a tendency for the gyres to flow in the opposite direction. This circulation of water helps spread energy from the Sun. The Sun warms water at the equator and then water and heat are transported to higher latitudes.
An example is El Nino. El Nino is a name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru. In El Nino years, the Equatorial counter current intensifies in the Pacific Ocean.This current flows towards the east, and it is a partial return of water carried westward by the North and South Equatorial currents. The effect of El Nino brings changes of weather raising or lowering air temperature, and amounts of rain. These factors contribute to change the weather in different places and in different forms.
Answer 3:
Currents flow in complex patterns affected by wind, the water's salinity and heat content, bottom topography, and the earth's rotation. Upwelling brings cold, nutrient-rich water from the depths up to the surface. The earth's rotation and strong seasonal winds push surface water away from some western coasts, so water rises on the western edges of continents to replace it, which is why the ocean is so much colder on the east coast than the west coast. Marine life thrives in these nutrient-rich waters. Colder or saltier water tends to sink, so you can imagine that the waters off the coast of Antarctica are really cold. A global "conveyor belt" sets in motion when deep water forms in the North Atlantic, sinks, moves south, and circulates around Antarctica, and then moves northward to the Indian, Pacific, and Atlantic basins. It can take a thousand years for water from the North Atlantic to find its way into the North Pacific.
Oceans store a large amount of heat, so small changes in ocean currents can have a large effect on coastal and global climate as they carry enormous amounts of heat north and south.
Answer 4:
Ocean currents move warm and cold bodies of water around. Water has a specific heat capacity thousands of times that of air, and as a result are able to chill or heat the air over them, as well, as are the source of vapor that becomes clouds and precipitation.Simply enough, the Earth's air-flow patterns are atmospheric, but the air temperature and even moreso the precipitation depends on ocean currents.
Answer 5:
Oceans play a HUGE role in redistributing heat around the globe. Ocean surface water that is heated by the sun near the equator eventually makes its way to the high latitudes where it cools off. When it is cooled, it sinks. Eventually, that cooled water makes its way back to the equator where it wells up and becomes surface water again. The whole cycle then repeats itself. This system of upwelling, heating, cooling, and downwelling is called the global thermohaline circulation system. Itsprimary influence is to transfer heat from the equator to the highlatitudes. One fear related to global warming is that rapidly melting polar ice sheets could cause this circulation system to cease. Melting of ice sheets delivers huge influxes of fresh water to the polar oceans. Because freshwater is less dense than sea water, it sits on the surface of the oceans and prevents the sinking that is necessary to drive the circulation system. The effect of this is that the higher latitudes (England, for example) would become much colder because no warm surface water would be brought to the poles and the lower latitudes (around the equator) would become warmer because there would be no upwelling of cold water. |
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GURGLETROUSERS
Joined: 30 Dec 2009
Posts: 2643
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| Posted: Wed Dec 30, 2015 3:06 pm Post subject: |
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Quote, 'simplistic answers that match GT's conclusions.'
He must mean that what is happening is not unprecedented!
The sea level along the Yorkshire coast is the same as it was in 1947 when on a day outing to Saltburn I rode on a donkey along the beach, by the pier. The tide still rises and falls to the same places as then, to the edge of a low sloping wall, and out towards the end of the pier - I should know, nowadays I surf there!
I was shopping in York today. ( I live a mere 20 plus miles away and very much like York.) Summer used to be the season for the tourist invasions, but today, there were Japanese throngs oohing and aahing (so it sounded) by the Minster. That must count as proof positive of climate change. What could be more convincing?
Sorry for not taking it seriously but I only live here, and can't compete with Google fed knowledge. |
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mrgybe
Joined: 01 Jul 2008
Posts: 5181
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| Posted: Wed Dec 30, 2015 3:27 pm Post subject: Re: Flooding in Great Britain, climate change and sea level rise |
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| mac wrote: | | It is easy enough to poke around the web.........and find simplistic answers. |
Indeed. |
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mac
Joined: 07 Mar 1999
Posts: 17749
Location: Berkeley, California
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| Posted: Wed Dec 30, 2015 3:40 pm Post subject: |
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Three thoughtful responses--not. The proud owner of a closed mind trolls, and GT goes blithely past the conclusion of the responsible flood control agency that dredging the river is not feasible without bothering to comment. No thought about budgets or institutional capability--somebody must have done something, and the money will magically appear. What passes for deep thinking in the conservative bubble.
So just a few facts on sea level rise in Northern England, which is still undergoing some isostatic rebound from the last ice age:
| Quote: | In northern Great Britain, whilst the sea level has been rising so has the land mass, meaning that the relative effect is less marked than in southern England, although it obviously remains an important consequence of climate change.....
The record from this site [North Shields Tide gauge] shows a measured rise in relative sea level between 1901 and 1996 of 1.86mm/year, with a standard deviation (confidence band) of ±0.15mm/year.
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http://www.climatenortheast.com/manageContent.aspx?object.id=11726
The net sea level rise is thus 1.86 mm/year, lessened somewhat by the rebound. |
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swchandler
Joined: 08 Nov 1993
Posts: 10588
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| Posted: Wed Dec 30, 2015 3:46 pm Post subject: |
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| G.T., maybe England is different, but I will say that here in California that there has been significant beach erosion over the years. Seems that the surf and tides are ever carving away at the shorelines. In some places, the erosion that has occurred is huge in just the last 20 years, and I should point out that notable steps were taken about 10 years ago to reenforce the beach with imported cobblestones, many of which are quite large. While I'm not one to adamantly push the idea of man made global warming and its impacts, there's no denying that some California beach areas are sorely losing the battle against the sea. |
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nw30
Joined: 21 Dec 2008
Posts: 6485
Location: The eye of the universe, Cen. Cal. coast
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| Posted: Wed Dec 30, 2015 6:26 pm Post subject: |
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mac, being a very good student of Rahm Emanuel "never let a good crisis go to waste", probably typed out his dissertation with glee.
And now for the rest of the story.
England has gotten one month's worth of rain just since Frank hit, that's a shit load of water in a very short amount of time, no place with slight topography, can drain that fast to avoid flooding. And it has been this bad before, this is not the first time, the last time being in the 50's.
http://www.dailymail.co.uk/news/article-3378081/Looters-target-flood-victims-homes-Thieves-steal-properties-submerged-dirty-water-Storm-Frank-threatens-6in-rain.html
Interesting, no mention of the flooding that we now have along the Mississippi, and that is very far away from the ocean. Now how did that get forgotten?
Interesting, no mention of El Nino either. Remember El Nino effects the weather all over the globe, not just along the west coast. Now how did that get forgotten also?
Answer, they weren't forgotten, just avoided.
I'll end with this~
http://www.washingtonexaminer.com/pew-americans-the-least-concerned-about-climate-change/article/2579150
Last edited by nw30 on Wed Dec 30, 2015 6:32 pm; edited 1 time in total |
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GURGLETROUSERS
Joined: 30 Dec 2009
Posts: 2643
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| Posted: Wed Dec 30, 2015 6:30 pm Post subject: |
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SWC. As I've previously stated in detail,relative land/sea levels in our island are subject to isostatic adjustment. It was a subject I studied as a student, but that is not the point I now wish to make to you.
I will no longer answer Mac. Twice, now, he has deliberately accused me of holding a view I do not.
His latest quote; 'GT goes blithely past the conclusion of the responsible flood control agency that dredging the river (the Ouse) is not feasible without bothering to comment.'
Read one of my previous posts SWC, where I stated, quote
'I thought I made clear that both widening and dredging the river Ouse was NOT A PRACTICAL PROPOSITION,AND NEITHER WOULD IT MAKE A GREAT DEAL OF DIFFERENCE.'
That was in response to the first time he altered my meaning - yet he now does so again! |
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isobars
Joined: 12 Dec 1999
Posts: 20935
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| Posted: Wed Dec 30, 2015 7:58 pm Post subject: |
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| nw30 wrote: | | Interesting, no mention of the flooding that we now have along the Mississippi, and that is very far away from the ocean. |
Well, SHEESH ... it's OBVIOUS that's caused by global warming. It's that darned sea level rising up the Mississippi.
Again.
It's not like it hasn't happened before:
1 Flood of March 1543
2 Flood of 1734-35
3 Flood of 1788
4 Flood of 1809
5 Flood of 1825
6 Great Flood of 1844
7 Great Flood of 1851
8 Great Mississippi Flood of 1927
9 Great Flood of 1937
10 Flood of 1945
11 Mississippi Flood of 1973
12 Flood of 1975
13 Flood of 1979
14 Lower Mississippi Flood of 1983
15 Great Mississippi and Missouri Rivers Flood of 1993
16 Flood of 2002
17 Flood of 2008
18 Great Mississippi Flood of 2011
19 Flood of 2014
And that's just some of them. NOAA's list at
http://www.srh.noaa.gov/lix/?n=ms_flood_history
is much longer, and it covers just the lower Mississippi.
Man, that's a lot of global climate changes. One might almost be tempted to call it ... oh, I dunno ... WEATHER.
Was THIS -- my home town -- global warming, rising sea levels, or just a boatload of rain (that's the second story of the courthouse, shot from the west):
Or was THIS ... same city center, taken from the NE, different flood?
Shit happens. It ain't always global. |
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swchandler
Joined: 08 Nov 1993
Posts: 10588
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| Posted: Thu Dec 31, 2015 3:52 am Post subject: |
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| G.T., I have to say that my comments really had nothing to do with mac's point of view of things. My comments were solely based on my experiences. I've been a beach guy since 1963 when I started surfing at 14. Believe me, I've seen a lot about what's happening, and I've pulled far more off the beach than most. My point about beach erosion is based on a long history of experience. Few folks have worked the beach as diligently I have. It's a wonderful place that I know very well. |
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