USGS tries to come up with answers after San Jose flood

Thursday, February 23, 2017 07:08PM
The USGS has been conducting surveys of Coyote Creek after flooding ravaged a nearby neighborhood in San Jose as residents are asking why they didn't get more notice to evacuate.


SAN JOSE, Calif. - The USGS has been conducting surveys of Coyote Creek after flooding ravaged a nearby neighborhood in San Jose as residents are asking why they didn't get more notice to evacuate.

On Tuesday and Thursday, field crews collected stream-flow data at Coyote Creek to help safeguard lives in the future.

According to the agency this is by far the highest Coyote Creek has ever been since a gauge was installed in 1991. That means there was no good data for what happens when the creek gets this high, there were only educated guesses. Mathematical flood models exist, but there isn't enough data for them to be reliable when there's this much water in the creek.

Five years of drought conditions in California have reduced the creek's capacity because so much debris and plant life has accumulated in the creek bed. Normally, there are heavy flows every couple of years to wash that debris away, but with five years of accumulation, the creek was full of vegetation and held far less water than the models predicted.

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The USGS has gone out to take measurements before and after the creek hit its peak stage on Wednesday, which was about 18 feet. The previous record was 13 feet. At that level, they calculated there were about 8,400 cubic feet per second of water moving through the channel. That's a whole lot of water.

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The new measurements taken today and on Tuesday will allow the USGS to create new, more accurate flood models that are based on sound science and adequate data. With the data water managers will have a reliable way to predict what flooding will look like downstream with so much water in the creek.

"If we had this data a week ago, we might have known that the river was going to get as high as it was, and they might have made a different decision than was made," USGS Field Office Chief Anthony Guerriero told ABC7.

But, Patrick Ferraro, a former water board member who teaches civil engineering at San Jose State says a careful look at the flood maps should have given city leaders a clue. "I moved my chickens Sunday. I knew this was going to happen. So, yeah they could have ordered everyone to start evacuating, at least packing," he said.

The storm washed away a significant amount of the debris that was clogging the creek, meaning that within a week or so Coyote Creek will be back to its pre-drought capacity.
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