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How Experts Make Flood Predictions
IOWA CITY (CBS 2/ FOX 28)--You don’t have to be an expert to see that the levels of the Wapsipinicon River are a lot higher than normal.
But it does take some expertise to figure out when and where that river will reach its highest point.
“We’re keeping an eye on rain,” said Ricardo Mantilla, researcher at the Iowa Flood Center. “Every time a drop of rain falls in Iowa, we know how that drop of water is going to get out of here.”
The more rainfall, the higher the river, and the higher the chances a surrounding area will get flooded said Mantilla.
“The moment it lands we make a prediction of where that rainfall is going to be in the next seven days,” Mantilla said.
A colorful map helps them do that. Each square represents one of the 150 gauges which measures rainfall throughout the state.
“What we do is try to predict what’s going to happen in the future,” he said.
But the guys from US geological survey are a bit more hands on.
Manual sonar gauges are dropped to the bottom of rivers to see how high waters will rise.
“We use an acoustic signal, those bounce back off the sediment in the water, measures the Doppler shift and you get your total volume,” said USGS hydrologist Lance Gruhn.
But that’s not always easy-- cuts in funding give them fewer and fewer gauges to work with.
“We’re losing gauges by the year,” Mantilla said. “That just increases the uncertainty of what we can tell the public.”
So while their system works, it’s not foolproof.
“The more information you have the less you have to guess,” Mantilla said.