Friday, May 13, 2011

Old Man River

So I've been half-following the story of the Mississippi flooding, and it reminded me of an article in the latest National Geographic (dead tree, no link) about Bangladesh. They breached a dike to reduce the level of the river, and the silt it deposited raised the level of the flooded area by five to six feet. I can imagine that the silt the Mississippi deposits will have an effect of the same sort. What this means for the cities, however, is that next time a flood happens, they will be, by comparison, on even lower ground. In addition to breaching the dikes, they should begin making plans for saving the city from the next flood now--before the river crests again. We won't do it, of course. Once the crisis is past it is forgotten.

1 Comments:

Blogger Yoel Natan said...

That level of silting won't happen in the spillway because the Mississippi gradient is greater than any Bangladeshi river, so the river doesn't slow enough or pool enough to drop its silt load, which load may not be as soupy in the first place:

Bangladesh: "Since 90 percent of Bangladesh is only about 10 meters (33 feet) above ... The rivers often silt up (become filled with soil) to form marshlands (soft, wet areas)."
www.nationsencyclopedia.com › Afghanistan to Comoros

10:59 PM  

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