State, Federal Officials Discuss Derecho’s Impact
State and federal climate scientists are continung to study the Aug. 10 storm that extended across much of the Highway 30 corridor in Iowa, ripping down trees, flattening corn and tearing apart homes, barns and businesses.
The USDA Midwest Climate Hub, National Oceanic and Atmospheric Administration, Iowa Department of Agriculture and Land Stewardship and Iowa Department of Natural Resources convened a webinar on Sept. 3 to discuss the science and impacts of the unusual storm, known as a derecho. (The term was coined by a University of Iowa physics professor in the 19th century.)
The nearly 6 million acres of corn and soybeans that were damaged by the heavy winds and hail have received attention, in part because the flattened corn widely is visible, even from space.
But Justin Glisan, Iowa’s state climatologist, estimated 300,000 acres of specialty crops were also damaged including tomatoes and other fruits and vegetables.
“We saw lots of damage to specialty infrastructure and growing tunnels,” he said. Steel and aluminum structures covered with cloth are often used to start vegetable plants in the spring and some crops grow in them the whole season.
Glisan shared a photo from Eric and Ann Franzenburg’s Pheasant Run Farm in Benton County that showed a twisted structure with almost no sign of the cloth.
The canvas got torn off and then Glisan said it just acted like a sail, furthering damage to the rigging and the structural components of the tunnel.
“We see this within the swath of the derecho,” he said, "these specialty, smaller-scale farms very much impacted by the wind."
Trees grow prepared to sway and twist in the wind, but many took on much more than they could manage during the storm, said Emma Hanigan, urban forestry coordinator for the Iowa DNR. She said Iowa’s tree canopy was already declining before the storm and the widespread loss of branches and whole trees affected state parks, urban public lands and private properties.
Hanigan said Cedar Rapids estimates it lost up to 50 percent of the city’s trees, which could translate to $3 million annually in lost benefits from them.
Trees retain water and sequester carbon, their shade helps reduce utility bills and Hanigan said research shows they improve people’s health. But she says public trees have not always been evenly distributed in communities.
“We see that tree cover is strongly correlated with economics,” she said, “and we have opportunity to spread that canopy out to our community and provide more equity.”
She did caution that replanting should be done deliberately and with certain things in mind, including diverse native species, which will increase resilience as different trees will grow to various heights and have different types of branching. Also, pruning and other care, especially in the first decade of new trees’ growth, is very important, she said.
Derechos occur once or twice a year in this part of the Midwest, said Ray Wolf, of NOAA, but they aren’t usually as intense, as long-lasting or as far-reaching. For example, 10 to 20 minutes of intense winds with gusts approaching 100 miles per hour might be typical, while this storm sustained that intensity for nearly an hour in the Cedar Rapids area.
“This is likely to tally up as another billions dollar disaster,” he said, putting it on par, in that sense, with the 2019 flooding along the Mississippi and Missouri rivers.
The derecho took the lives of two Iowans and one person in Indiana.
“It’s rather amazing there weren’t more fatalities with an event of this extreme nature,” Wolf said.