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Rudi Kiefer: Let’s learn from California’s mistakes
Rudi Kiefer
Among all the environmental disasters of the past few years, floods are clearly in the top position. For residents along the Feather and the Sacramento rivers in California, 2017 was a tense year because structural problems at Oroville Dam led to worries about catastrophic flooding.

On Feb. 2 last year, engineers observed that the spillway, which drains excess water from the dam, was breaking up. Cracks in the concrete bed led to slabs breaking off.

Similar to North Georgia, the soil in that area is soft clay. Just like the erosion gullies we see here on unprotected hill slopes, overflow from a month of heavy rain carved deep grooves. Finding more soft ground at the side of the spillway, it left its concrete bed and dug a new ravine.

As the main spillway came apart under the force of the overflow, operators tried to drain water over the emergency spillway, which has a concrete top lip (called a weir) but no hard liner.

Digging into the soft ground below the weir, the torrent began to make a path which had the potential of collapsing the channel. Local authorities saw the possibility of disastrous flooding, affecting in geographical order the cities of Oroville (population 15,000), Yuba (67,000) and up to 2.4 million people in Sacramento’s metropolitan area. After evacuation of nearly 200,000 residents in February, a race around the clock began to stabilize both spillways.

At 770 feet, Oroville is the tallest dam in the U.S., but the worry isn’t about the main structure. It’s about a breach of the emergency spillway.

A hole below the weir would quickly tear open to form a gigantic water jet, with flood waves racing down the Feather River and into the Sacramento.

Re-engineering during the past 11 months seems to be successful in stabilizing the two spillways. But this month, an independent investigation concluded that it wasn’t really a “natural” disaster that had been avoided. Faulty engineering was to blame for the poor layout of the main and emergency spillways.

On the administrative side, the California Department of Water Resources has been accused of poor oversight, internal feuds between its units and inexperienced engineers in charge of major structural designs. The U.S. Southeast, with its hundreds of lakes and dams, will do well to learn from this episode of political grandstanding vs. responsible environmental engineering.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.

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