How Des Moines boosted flood defense ahead of record rains
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Des Moines has 11 "stop logs" sites along its levee systems to help prevent flooding. Photo: Courtesy of the city of Des Moines
National Weather Service offices across the U.S. have issued a record number of flash flood warnings so far this year.
Why it matters: Although the Des Moines metro hasn't reached a historic number of warnings this year, the severity of recent storms has exceeded previous records, leaving many residents dealing with trail closures, road disruptions and flooded basements.
- Scientists who spoke to Axios say the events highlight the risk that climate change can worsen extreme rainstorms.
The latest: Storms that developed Sunday did not quickly move out of parts of Des Moines, bringing significant rain.
- The total at Des Moines International Airport was 2.77 inches, exceeding the previous July 20 record set in 1907 by more than a third of an inch.
- In total, Des Moines received over 4 inches of rain in the three days ending Sunday, WHO-13 reports.
The intrigue: DSM also recorded nearly 4 inches of rain on May 19, setting a one-day record for that month.
State of play: Flash flood warnings are issued when a flood is imminent or already occurring.
Zoom in: As of Sunday, Des Moines has experienced 13 flash flood warnings this year, well below many previous years.
- The record (120) was set in 2008, the year the Birdland Levee breached, damaging hundreds of homes.
- Since then, over $150 million has been invested in rebuilding or upgrading the area's levees and stormwater systems.
Zoom out: NWS offices issued 3,160 flash flood warnings nationwide this year through last Wednesday, according to a tracker at Iowa State University's Iowa Environmental Mesonet.
- That's the most for that period in any year since tracking began in 1986.
Worthy of your time: Over the past decade, the city of DSM has also installed dozens of "swing gates" or "stop logs" along its levee system to quickly boost flood protection. A recent video demonstrates how they work.
The big picture: Warmer air holds more water. As our planet gets hotter, storms are becoming more intense and dropping more rain.
- Topography, geology and drought can also worsen flooding.
- For every 1 degree of warming, the air can hold 4% more moisture, according to Climate Central, a nonprofit climate research group.
What's next: Some of Des Moines' levee improvements will continue for at least three more years.