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Do Like the Dutch Do?

by asdf Tue Sep 6th, 2005 at 03:14:13 PM EST

"Old Europe": planning ahead and paying for it - imagine that? promoted from the diaries ~ whataboutbob

It's been proposed that America should look to the Netherlands for ideas about how to build a storm-proof sea wall. How much would that cost?

I'm not an expert on this by any means, but looking under various internet rocks here's what I found: It would be BIG BUCKS. But the results might be worth it.

"After the 1953 [giant storm in the English Channel] disaster, the Delta project, a vast construction effort designed to end the threat from the sea once and for all, was launched in 1958 and largely completed in 2002. The official goal of the Delta project was to reduce the risk of flooding in Holland to once per 10,000 years."

Is that good enough? Perhaps. Now, how much would it cost?

"(For the rest of the country, the protection-level is once per 4,000 years). This was achieved by raising 3,000 km of outer sea-dikes and 10,000 km of inner, canal, and river dikes to "delta" height, and by closing off the sea estuaries of the Zeeland province. New risk assessments occasionally incur additional Delta project work in the form of dike re-enforcements. The Delta project is the single largest construction effort in human history and is considered by the American Society of Civil Engineers as one of the seven wonders of the modern world."

How does this compare to the situation in the U.S.? First, the Dutch coast wanders in and out with numerous penninsulas and bays, while the American coast is relatively straight. The Intracoastal Waterway is about 4800 km (from Boston to Brownsvill), which gives a rough idea of the scale of a proposed comprehensive rebuild plan: As a first cut, it's about half the length of the Dutch project. (I'm not too sure about this estimate, because obviously there are many rivers that would have to be considered. It seems odd that the effective Dutch coast would be twice as long as the American East and Gulf coasts combined.]

"A decade ago, Dutch authorities started studying their options for dealing with not only sinking land, but rising seas, more powerful storms, and ever larger floods. Government engineers considered several strategies, including a plan to simply surrender large parts of the country to the sea. The most cost-effective plan was selected: strengthen the existing defenses and pumping stations, at a cost of $19 billion to $25 billion.

"These are enormous figures if you had to spend them all at once, but we're able to spread it out over 50 to 100 years," says John de Ronde of the National Institute for Coastal and Marine Management in The Hague, which prepared the estimates. "And it's relatively simple for us to cope with sea-level rise because we already have [U.S. $2.5 trillion worth of] existing infrastructure.

"If you really have to start from scratch and build all of this infrastructure, you'd probably have to consider giving the land to the sea," he says. It's a situation low-lying regions from Bangladesh and the Marshall Islands to southern Louisiana and the Florida Everglades may soon be facing."

So, does America have $2.5 trillion of existing coastal infrastructure? Impossible to say (at least, for me to say). I don't know what the starting point would be.

But how do these numbers compare with, say, the cost of the war in Iraq?

According to the Wikipedia, about $75 billion. The Dutch are planning to spend about 1/3 of the cost of the Iraq war, spread out over decades, on their sea wall improvement program.

Note that there are environmental aspects of this, too. The current waterway has lost environmental court cases and any improvement program would have to deal with this concern. "As a result of the settlement of a lawsuit with the Lower Laguna Madre Foundation and Audubon Society, the Corps only performs emergency dredging on the Waterway between Corpus and Brownsville. Although navigation has not been affected, this uncertainty impacts negatively on the ability of the ports to market their services. Louisiana's Coast 2050 Program, along with the U.S. Fish and Wildlife Service's proposal to designate thousands of acres of Gulf Coast wetlands as critical Piping Plover habitat, threaten viability of the Waterway. Left unanswered, these initiatives have the power to stop all maintenance dredging on the Waterway."

It's clear that it will be hard to find the proper balance between commerce, safety, the environment, and other expensive programs.

It's been proposed that America should look to the Netherlands for ideas about how to build a storm-proof sea wall. How much would that cost?

Less than the current disaster.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Tue Sep 6th, 2005 at 03:34:21 AM EST
asdf, sorry for the shot-from-the-hip reply to the very first lines... while the rest of your the article essentially says the same!

Some minor notes to your article. I share your non-professional suspicion that rivers that won't be closed, maybe bays too, and - well - parts of the built-up Mississippi Delta would have to be considered, so the effective length wouldn't be so much shorter than for the Netherlands that is criss-crossed by the Rhine and canals and has lots of sub-sea-level land in need of multiple lines of protection.

I didn't found your $75 billion Iraq War reference at wikipedia. However, Costofwar.com, which is based on actual budget requests, is now at $192.5 billion.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Tue Sep 6th, 2005 at 04:37:17 AM EST
[ Parent ]
If you unfold the Greek coastline, you could wrap it around the earth....
by PeWi on Tue Sep 6th, 2005 at 05:09:11 AM EST
Now you are just being Mandelbrotian for the hell of it ;-)

You can't be me, I'm taken
by Sven Triloqvist on Tue Sep 6th, 2005 at 03:26:02 PM EST
[ Parent ]
Well, the colour simulations on my Sinclair QL, where not as close to the real thing as I would have wanted. But they sure made good wallpaper...
by PeWi on Tue Sep 6th, 2005 at 03:28:31 PM EST
[ Parent ]
well it is quite clear now that the Bush admin has been using wallpaper as a structural material for some time now....

You can't be me, I'm taken
by Sven Triloqvist on Tue Sep 6th, 2005 at 03:31:46 PM EST
[ Parent ]
I think you miss the point. The super-dykes (sounds like a lesbian comic book character but you know what I mean) that have been suggested are to protect the very high density and value areas. This would certainly be the city of New Orleans and what would become a ring of high walls surrounding the core could also be used as a ring road by adding a highway on top.

I have mentioned elsewhere that the main danger to the areas directly hit is the storm surge. That can be disipated by flora, either trees or wetlands. If the current rate of erosion of these goes ahead, the sea will lap the levees of New Orleans this centrury and by the end the level of the land will be at least 1 metre further below sea level due to the "sponge" effect of extracting water while no river silt is deposited because of the existing levees.

Areas of SE England have very high sea walls which would be needed if your idea goes ahead. Canvey Island is one such and is a traditional vacation and holiday home (mostly fixed trailers) for the working class of East London. If you visit, there are beaches but to get to them you have to climb up and over the sea walls. Not very attractive and certainly not like the existing coast.

The only practical way of managing land it would be too costly to "polderise" is re-establish the coastal flora and build the resorts much further inland. The artificial beaches that now line the shores could be re-established for the "seaside" resorts but housing that replaced the native woods and forests may well have to be abandoned and rebuilt inland. Quite frankly, no one will be able to get insurance to cover hurricane loss if their homes are in high storm surge risk area or it will be so prohibitive to be unaffordable.  

by Londonbear on Tue Sep 6th, 2005 at 08:26:48 AM EST
Canvey Island: The 1953 February flooding also caused hundred of deaths in SE England; I don't know what precautionary measures the Brittish government took in response to it. It could very well be sea walls, like the Dutch have'em.

Also, there's nothing costly about polderising sea. It's free. All you need is some wooden poles and time. Quite a lot of time, actually, but it works just fine.

But here I lost it:

If the current rate of erosion of these goes ahead, the sea will lap the levees of New Orleans this centrury and by the end the level of the land will be at least 1 metre further below sea level due to the "sponge" effect of extracting water while no river silt is deposited because of the existing levees.

That's one hell of a sentence and as I read it, it sounds wrong. I break it up in 2 parts.
1) Loss of wetlands will result in overflowing the levees
2)The "sponge" effect leading to lowering of the land is caused by extracting water and absence of depositing river silt

If that's correct with you want to convey, then I don't understand what you mean with the first point. Will there be overflow during a storm surge only, or in general?

Your second point is effectively solved by keeping a high groundwater level. The Netherlands have had a change in policy in this regard: pumping water out constantly increases the sponge effect, so they don't do it any more. The groundwater level is kept rather high to reduce land lowering. The risk comes during heavy rainfall, then the pumps need to get rid of the extra water fast. The absence of depositing river silt is only marginally important; it's groundwater that's the key.

by Nomad (Bjinse) on Tue Sep 6th, 2005 at 01:09:10 PM EST
[ Parent ]
Sorry, it's a double effect. The silt being carried down the river would usually be deposited on the land now nbehind the levees. I seem to remember that the rate of non-deposition was something like 1 metre a century. All things being equal, the flow of silt down to a river delta should increase the land area as the soil builds into mudbaks which are colloised by plants and become dry land. Instead the levee system means that this slt is being bumped onto the river bottom and the big lake to the north. That in time means you have to raise the levees to accommodate the flow. As the silting/reiver bed rise/levee rise continues, the land within the levess becomes relatively lower.

The sponge effect I was alluding to is what happens when you dry one of those articifical car cleaning sponges. As you remove more and more water, the volume shrinks as subsidence. This effect is very common in East Anglia where the rivers are far higher than the surrounding fields.

Yes Canvey Island was flooded in 1953 and the very high sea walls were built after. They help protect some oil refineries as well as residential/vacation areas.

by Londonbear on Tue Sep 6th, 2005 at 01:39:19 PM EST
[ Parent ]
Apologies was rushing as have to go to a meeting and did not notice the typos. Anything unclear get back to me and I will respond later.
by Londonbear on Tue Sep 6th, 2005 at 01:41:41 PM EST
[ Parent ]
... if I follow your reasoning correctly, then why aren't we constantly raising the dikes in the Netherlands? Or, for that matter, in East Anglia? I can tell you, we aren't.

You seem to have knowledge about sedimentology, but I can't tell how much of it is your background. However, I can't help spotting some serious flaws. Silt that's not deposited on land doesn't get bumped in the river instead. It's a simple matter of energy: small particles will deposit in a low energy environment, e.g. when a river breaks through a levee. The water in the river trapped within the levees has enough energy to carry the silt all the way down to the delta. There it reaches open water, the energy disperses, the sand and silt go down. Wham, you got your delta. The flow accommodates the river, not the other way around.

Also, lake Pontchartrain is not directly connected to the Mississippi, so there won't be much sediment deposited into the lake. (The lake IS connected to the ocean and that's actually a bad thing during a hurricane. Fill up the lake or close off the connection, people.)

River management is, however, extremely important, that's where I completely agree. I'd caution against pumping wetlands dry beside the levees for 2 reasons:

  1. the "sponge" effect, leading to land subsidence, hence greater levee seepage and increasing dam instability
  2. Raising the levees won't help when the rain hits hard. A river needs space. Allow space and allow flooding. That is, allow the river its surrounding wetlands, minimally at one side. That's the river's escape space when the water levels rise.
Don't build houses there.
by Nomad (Bjinse) on Tue Sep 6th, 2005 at 05:24:49 PM EST
[ Parent ]
  1. Hazard Evaluation. This may be stating the over-obvious: What's wrong with flooding when it's uninhabited country? Coast line defenses in the Netherlands is everywhere because it's so densely populated and 1/3 of the country is below sealevel. That's simply not the case for the USA. Look what's necessary to protect cities like New Orleans and Houston; figure the price tag on that amount of coast.

  2. Another advice: get those bloody villa's off the East Coast barrier islands right now. You just need one tsunami or major storm for yet another (financial) disaster to happen. They're called barrier islands for a reason; they're BARRIERS, they're not to build houses on.
by Nomad (Bjinse) on Tue Sep 6th, 2005 at 01:43:52 PM EST
d assumedthat the lake was part of the river system as it looks a bit like a huge "oc bow" type lake from the pictures.

My understanding of the hydrology of the river system is that it used to be a broad, very slow flowing river. When the river inundated the land that is now the lowest part of NO it allowed, as you say, the silt to precipitate out. That process was common to many major rivers and the Nile valley's productivity due to such flooding and depositing of nutrients built to country.

The main river at NO like most of its lower valley, is highly contrained by a system of levees and this does indeed increase the flow so main river silt is deposited way out to sea. Too far out to add to banks and swamps to build them up. NO also has canals and these alter the river's flow so that silt deposition can occur. With the river contrained in artificial banks, this reduces to total volume of water the system is able to hold. With nowhere to go but up storm surges make the tidal river overflow unless the levees are built higher.

If you compare maps of east London and NO  you will see both have large U bends where the rivers have meandered in the past. In London's case this formed the area of the main docks and, further back. wet reed beds. In those days, when the Thames had high water levels, it merely inundated the Isle of Dogs and took the shortest route. In NO that route is straight through the city.

Dutchman is right, the ultimate solution is not more and more constraints but allowing the river to manage itself naturally in areas where the costs of having floods are minimal. Just such a solution is proposed to protect the new developments in the Thames valley below the Barrier. As well as river walls, areas will be allowed to flood to absorb the excess water. Similar plans are already in place in East Anglia where the sea walls have been deliberately breached to allow the fields to revert to salt water marshes.  

by Londonbear on Tue Sep 6th, 2005 at 07:26:36 PM EST
[ Parent ]
Interesting post, thanks. I'm impressed with the Dutch foresight...

"Once in awhile we get shown the light, in the strangest of places, if we look at it right" - Hunter/Garcia
by whataboutbob on Tue Sep 6th, 2005 at 03:16:17 PM EST

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