JOHNSTON — Ten years after historic floodwaters swept through Cedar Rapids and a day after the city received $117 million to protect against future flooding, a University of Iowa hydrologist warned against fighting the last war against high water.
“I think that there’s a trap that we often put ourselves in that we plan for the largest historical event that happened and we think that nothing bigger can happen and then it happens,” Witold Krajewski, director of the UI Flood Center, said Friday.
Noting that more than half of Iowa counties have had at least nine presidential disaster declarations since 1988 and 14 of those have had between 13 and 17, Krajewski said flooding may be a larger problem than people think.
“We’ve got problems here,” said Krajewski, who joined Cedar Rapids City Ccouncil member Tyler Olson on Iowa Public Television’s Iowa Press. Their discussion can be seen tonight at 7:30 p.m. and noon Sunday on IPTV, at 8:30 a.m. Saturday on IPTV World and online at www.IPTV.org.
Iowans may think of flooding as an unusual event, but it’s happening every two or three years, he said, which suggests the state and local governments are not taking adequate measures to protect against flood.
Also, Krajewski said, as temperature and humidity slowly rise, the conditions favorable for precipitation increase. In Iowa, he added, flooding is mostly the result of rainfall over the state and upriver from Iowa.
Cedar Rapids is taking the flood threat seriously, said Olson, who was a state legislators in 2008 when the city sustained more than $5 billion in damage.
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Over the next 10 to 15 years, he said, the city will spend about $750 million — including the $117 million announced by the Army Corps of Engineers Thursday — on flood protection including a series of earthen levees, removable flood walls, permanent flood walls, including some integrated into the structures built along the Cedar River through the downtown area.
Olson and Krajewski agreed that having up-to-date information, such as flood plain maps, and protecting critical infrastructure such as water and power supplies are essential to protecting communities against flood damage.
In many communities Krajewski said, development regulations are based on the idea of the 1 percent annual chance of a 100-year flood. However, over 30 years — the length of a typical home mortgage — the probability of such a flood is 26 percent.
Critical infrastructure, he added, should be protected to an even lower probability of a major flood event.
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