From a magazine that used to be really good - Scientific American:
California Dam Crisis Could Have Been Averted
By now we have all seen the spectacular images of volumes of water crashing down the Oroville Dam spillway in California and blasting upward into the air as they hit an enormous crater in the spillway floor, flooding down the adjacent hillside, threatening people in towns below. Those images reveal a big mistake: failure to update infrastructure to defend against climate change.
The menacing floodwaters last week forced the emergency evacuation of 188,000 residents. Yet the impending disaster came as no surprise to officials in Butte and Plumas counties. The rural counties, which surround Lake Oroville, had challenged the state’s environmental review of dam operations in a 2008 lawsuit, arguing the state "recklessly failed" to properly account for climate change in its long-term dam management plan.
The dam was built in the 1960s when temperatures were cooler and more precipitation was stored in a greater snowpack in the mountains of the Feather River watershed, which drains into Lake Oroville. Today warming temperatures are bringing more rain as well as melting the Sierra Nevada snowpack earlier in the spring. As the counties’ attorneys predicted, among the results is a rush of downhill water much faster than in the past. “We anticipated that this crisis might come about,” says Tony Rossmann, special counsel to Butte County.
So many logical flaws, so little time.
Warm weather does not necessarily bring more rain - warm air holds more water by volume than cool air so if it is warm, there is less chance of rainfall. The real cause was lack of maintenance and it looks like the concrete spillway was not built well to begin with. The dam was built in the 1960's when it was cooler - yes, so cool that the climate scientists were yammering about global cooling - the next ice age. Here is the rainfall data for Los Angeles dating back to 1877 - see for yourself. There are ten years or so of minimal rainfall and then a year or two of well above average. This is called climate and there is nothing unusual in this pattern - it is normal for the Los Angeles area.
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