The recent rains on the West Coast have caused many of the rivers there to flood, threatening many cities as well as cropland. Levees are being overtopped and mudslides and fallen trees are blocking roads through the region. You can read more about the impacts of the storm and view pictures of the conditions at SFGate.com here.
Wired.com noted that officials were opening weirs (gates) on levees in the Sacramento area to allow flood waters to flow into fields rather than flood vulnerable areas in cities. This is the first time it has been done in a decade as the area has been gripped in recent years by an extreme drought. You can read about how they manage the water flow at https://www.wired.com/2017/01/california-flooding-keep-cities-flooding/.
This is not the only time that serious flooding has been a problem in California. In fact, the Wired article notes: “All of these checks and balances are in place because California’s tendency to flood is almost as notorious as its habit of running dry. “Turns out, we have the most variable climate in nation for water,” says Marty Ralph, research meteorologist and director of the Scripps Institution’s Center for Western Weather and Water Extremes. “Year to year, we vary by 40 or even 50 percent from average.” Most eastern states only fluctuate by 10 percent either way.”
Scientific American published a recent article describing one of the worst floods in the history of California. In 1861 a massive flood that affect central and southern California occurred after 43 days of heavy rain. According to the article, “this disaster turned enormous regions of the state into inland seas for months, and took thousands of human lives. The costs were devastating: one quarter of California’s economy was destroyed, forcing the state into bankruptcy.”
