Los Angeles is centered where it is partially because of the Los Angeles River, the city's original source of fresh water. Owing to local geography it had a tendency to meander and flood at unpredictable degrees, and so in an initiative that should come as no surprise in a place like southern California, the river was paved over and almost entirely transformed into a concrete-lined flood control channel. To me, it's just another reminder that we've been managing our environment at one scale or another for a long time - better in some ways than in others.
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