Andrew Revkin, in the New York Times Dot Earth blog, writes about a collection of large urban streams being “daylighted,” i.e. unearthed from massive underground pipes they were routed into.
The article is very link-rich, go take a look. Here’s another take on a $384 million project in Seoul mentioned in Revkin’s article.
Near here, the River des Peres in St. Louis was routed underground in a huge project beginning in the 1930’s. Another article here. You could drive eighteen wheelers abreast through some of the conduits.
The flickr user “cicadashell” has some nice photos of the River des Peres here, the one above (used with permission) shows a section that was converted into a concrete trapezoid.
And, finally, “Misfit Stream” an interesting eco-blog about efforts to restore environmental values to the City of St. Louis.