Kemper Arena. The West Bottoms. Parts of the Country Club Plaza. Swope Park. Large swaths around the Blue River and Indian Creek. Nearly 2,100 homes across the city.
That’s just a glimpse of what a 500-year flood would be like if it happened in Kansas City, according to floodplain maps.
Events like the flooding after Hurricane Harvey in Houston are unprecedented.
But could it happen here?
“A 500-year event is almost unimaginable,” said Stephen Bean, emergency operations coordinator for Kansas City.
“It’s not conceivable to have 50 inches of rain here because it takes a hurricane or tropical storm feeding off the ocean to create that event. We’re not going to see that kind of flooding here. We’re also not flat as a pancake, which is part of what’s going on in Houston. Here we have valleys and watersheds, so it’s somewhat predictable for us where the water will flow.”
If Kansas City were to have a major 500-year flood event, it would look very different.
So what is a 500-year flood?
“The best way to describe a 500-year flood is that it’s a flood that has a .2 percent chance of occurring in any given year,” said Bob Franke, a senior civil engineer at the Federal Emergency Management Agency in Kansas City. “It’s not every 500 years. It could be once every 10 years.”
Any waterway has the potential for a 500-year flood, and some waterways in an area could have that level of flooding while others nearby do not, depending on the topography of the area and any infrastructure.
Smaller waterways tend to be more prone to flash flooding, while water levels in rivers rise more slowly and fall slowly, Franke said.
The flood of 1951 was a flood of record, Franke said, and river-based floods like that one have the potential to damage a larger area.
“Would we ever expect to see a 50-inch rainfall here? I don’t think so,” Franke said. “Ten inches in 24 hours? Yes, that starts to get us into what is classified as a 500-year rainfall event, but that doesn’t necessarily lead to a 500-year flood.”
To better understand which areas are more prone to flooding, the federal government began creating maps of special flood hazard areas in 1971.
Properties with federally backed mortgages within those designated areas are required to have flood insurance through the National Flood Insurance Program. The Kansas City floodplain maps were updated earlier this year. According to the Kansas City water department, there are nearly 2,100 addresses in the floodplain locally.
History of floods
To help prepare for future disasters, emergency management personnel look to the past.
And Kansas City isn’t a stranger to big floods.
In 1951, up to 36 people died across the Kansas River Basin in what’s called The Great Flood. At least five of those deaths were in the Kansas City area, and damage from the flood reached what today would be billions of dollars.
In 1993, the Missouri River flooded because of heavy rains over wide parts of the Midwest that just kept coming.
There have been flash floods, like the historic 1977 Plaza flood that killed 25 people from Leawood to Independence and caused millions in damage, most of it in the Country Club Plaza. Recent record rains also have led to flash flooding, submerged businesses and water rescues.
But as these events have unfolded, local governments and the U.S. Army Corps of Engineers have worked to mitigate future flooding.
Levees along the Missouri River should be able to withstand a 500-year flood, said John Grothaus, chief of the planning section for the Kansas City District of the U.S. Army Corps of Engineers, which manages 500 miles of river from Nebraska to the confluence of the Mississippi River.
On the Kansas River, while there are lakes and a levee system in place, a 500-year flood could do some damage, he said.
The levee system on that river is not high enough, so the Corps has been authorized to start a project to raise those levees by five feet. Design for the project began this year and will continue in 2018, but there isn’t yet a clear completion date since the project is largely dependent on federal and local funds.
In addition to the larger rivers, the Corps has completed and is working on projects along smaller waterways in the Kansas City area.
A 1998 flood along Brush Creek led to more projects to alleviate flooding there. In June, federal funding was announced to complete work along Turkey Creek, which includes channel widening, tunnel modifications and relocating bridges, primarily along Interstate 35 and Southwest Boulevard in Kansas City and Kansas City, Kan.
Engineers at Kansas City Hall and the U.S. Army Corps of Engineers have talked informally about a feasibility study to search for an Indian Creek fix.
In a major flood, emergency officials would deploy to the emergency operations center near Woodland and Independence avenues.
Workers there monitor 31 screens of satellite weather information and data from 160 sensors around the metro to gauge rain and river levels.
“It’s everything you’d expect to see at a mission control for NASA,” said Bean, the city’s emergency operations coordinator.
Officials would begin notifying people in areas that are at risk, telling them to prepare to evacuate or to evacuate, depending on the conditions.
“It’s all a matter of how much lead time you have,” Bean said.
If water breaches the levees around Kansas City, emergency personnel would begin to stage resources and start moving boats and rescue equipment. They’d also have barricade crews ready to go to block certain areas from public access.
The city also has a number of potential shelters across the area, Bean said, and they would give people direction on which ones were available.
“We’ve identified sites and have agreements with school districts, churches and other facilities around the metro. We take what we have,” he said.
It can take up to 72 hours for large shelters and outside emergency response teams to be completely in place after a major event, Bean said. Because of the extended time, he urges people to have enough food, medicine and emergency supplies like radios and flashlights ready.
“Everybody needs to look at these disasters, natural and man-made, and ask, ‘What would I do?’ They need to understand in Kansas City what our threats are... and not wait until the warnings go off. If there’s flash flooding, how do I get out of where I am? Where are the streams and creeks and rivers around me?
“I don’t want people to be scared, just be prepared. That’s how you feel safe.”