A gauge measuring the volume and level of the Turkey River at Spillville is so important to managing flooding in northeast Iowa that when Sean Snyder heard state funding was being cut, he convinced city and county officials to scrape up nearly $10,000 to keep the gauge running.
“I rely heavily on that Spillville gauge,” the Winneshiek County Emergency Management coordinator said.
In 2016, heavy rains caused the Turkey to crest at 20 feet — 11 feet over flood stage. “If it wasn’t for having that gauge in place, it would have meant downstream neighbors would not have had the warning they did,” Snyder said.
State and federal agencies have more than doubled the number of gauges and sensors on Iowa rivers, lakes and streams in the decade since the 2008 floods. The data coming from 530 devices allows for flood forecasting, inundation maps and even text or email alerts for Iowans in the path of rising water.
Building this network for flood prediction has involved many agencies, including the U.S. Geological Survey, Iowa Department of Natural Resources and the Iowa Flood Center, launched at the University of Iowa after the 2008 flood that devastated parts of Eastern Iowa.
“In 2008, I was frustrated that with my experience I couldn’t help,” said Witold Krajewski, a UI hydrologist whose specialty is in measuring, modeling and forecasting precipitation using remote sensing.
While they couldn’t stop the massive swell of water rushing down the Cedar and Iowa rivers in 2008, they could help agencies better prepare for, predict and monitor future flooding.
The Iowa Flood Center was created in 2009 with an initial $1.3 million from the state. One of the program’s early successes was developing an inexpensive water sensor that could be attached to bridges to measure water levels and immediately transmit the data back to the UI.
“They provide data in real time and we convey that to the public,” said Krajewski, Flood Center director.
The UI now has nearly 260 sensors across the state, supplementing gauges controlled by USGS and the U.S. Army Corps of Engineers.
The Flood Center pulls all the data into its Iowa Flood Information System, a user-friendly website that provides stream conditions, flood alerts and interactive inundation maps for 25 cities across the state.
The system has been used repeatedly when flood threats loom. Cedar Rapids officials also used the system when preparing for the September 2016 21.9-foot crest of the Cedar River, which the city fended off with temporary barriers and other efforts.
The USGS, which has operated some river gauges in Iowa for more than 100 years, now has backup gauges in key locations, such as Eighth Avenue in downtown Cedar Rapids, said Jon Nania, deputy director for Iowa.
“If one should fail, we can switch,” he said. “We know the importance of forecasting there.”
Because most USGS gauges provide river level and volume — as opposed to just the level from sensors — the National Weather Service can make river forecasts from those points. USGS staff also visit each gauge every six weeks to measure streamflow and make sure the device is operating properly, Nania said.
“Rivers, especially in Iowa, are very dynamic,” he said. “We go out to verify the relation still is the same.”
At the USGS WaterWatch website, users can click on a gauge site and request text or email alerts when the water reaches a chosen level. Snyder sets his Spillville alert for eight feet, but a typical homeowner might set it at 11 feet. If an alert sounds, the homeowner knows it’s time to get possessions out of the basement or consider sandbagging — actions that could prevent financial loss, Snyder said.
“It’s all part of the preparation.”
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