How about other major cities that are built on rivers?
The city of Winnipeg, Manitoba (pop. ~650k) is built at the confluence of two rivers, the Red and the Assiniboine. Moreover, the nearby land is incredibly flat, so once a river overspills its banks it can spread quite a long way; and the Red River flows north, meaning that spring run-off can get “backed up” as it flows into regions that aren’t yet fully thawed. As a result, over the last 50 years a fairly complicated system of diversion channels and reservoirs has been built to mitigate the risk of floods. Chief among them is the Red River Floodway, which shunts floodwaters around the city; the Portage Diversion and the Shellmouth Reservoir help to moderate the effects of the Assiniboine.
The Seine as it flows through Paris is far below the level of the street – maybe a story or two. This should give you an idea.
It would have to be a hell of a flood to overflow that.
Your question is a little broad. Are you speaking in terms of an emergency action plan in case of flood, or a flood mitigation strategy such as MikeS mentioned?
While the level of the Seine does rise and fall (I remember that in March of 2001, the walkways of the Île de la cité close to the water level were flooded to about two inches, making it possible to seem like you were walking on water. I have a picture of a friend of mine doing this somewhere), under most cirucumstances, the “higher” man-made stone banks of the river prevent flooding.
However, at times, the Seine does overflow these higher banks, such as the flood of 1910. The wikipedia article, 1910 Great Flood of Paris - Wikipedia , has some pictures. Apparently, the highest of the aqcua alta was about twenty feet above normal. Keep in mind that the height of the high stone banks is artificial, like a sort of man-made hill, and that once the river floods over them, the water can spread to a wide area.
If I am not mistaken, the Seine is dammed well upstream to minimize the possibility of another flood, as well as to keep the river navigable in the summer because without the dams, in the summer, the flow of the Seine would reduce to a trickle. This site, http://www.grid.unep.ch/product/publication/freshwater_europe/seine.php , has more information about that.
And of course in London there is the Thames Barrier
Between ass, boin, and Cinnabon, that’s the worst word ever to want to have someone take serious.
In fact it could happen. The river not being very large, a major flood could overflow that. But more likely, other parts of Paris would be flooded first, through drains, covered tributary of the river, the huge tunnels and former limestone quarries system still existing below ground and so on.
And yes there are prevention measures, dams, reserve lakes and so on. However, it would probably be insufficient to completely avoid damages in the case of a centenial flood (like in 1910), and there has been worse floods than that in the past (If I’m not mistaken the worst occured during the 18th century), especially since the urban area is obviously much more extended than it was one century ago.
There are certainly contingency plans, but I’ve no clue about what they entail. The only related thing I read recently was specifically about the Louvre plan in case of flood, and I forgot what it was.
Anecdotically, when the water level rises, a statue of a zouave is traditionnally used (in the medias for instance) to depict the water level .
Is that meant to protect against rain-induced flooding, or just against storm surges coming in off the sea?
I don’t think any contingency plan against flooding will be restricted to a single city. but rather to an entire region as a whole. As an example, after the 1953 flooding in the Netherlands which cost the lives of 1700 people, an elaborate system of dikes and dams (the Delta Works) was constructed covering a large part of the Netherlands. The most recent installment of the Delta Works (Maeslantkering) was finished in 1997 and was built specifically to protect Rotterdam while still allowing ocean-going ships to reach the harbor. It’s quite awesome to behold, actually. More generally, along the rivers crossing through the Netherlands, there are areas called ‘uiterwaarden’ which are not built up but only used as grazing land, and which can be flooded to allow more water to pass through. (wikionly has a Dutch page on these uiterwaarden, but there’s some nice diagrams so you get an idea).
Storm surges coming in off the sea - that’s why it’s downstream of the city centre.
The Thames is tidal all the way through London, so rain-induced flooding would only be dangerous when combined with a storm surge or high tide.
While a “watershed approach” is often the best one, there are many areas where the river system is just too large to deal with on a regional basis, given the lack of funding.
Why would Ms. Hilton have any interest in planning for flooding in France?