Willing to take the Risk?

Today's print column, a follow-up to Sunday's column.

The Army Corps of Engineers' assessment of Cedar Rapids' future flood risk has a gap.

“The official government policy has been pretty strongly stated that there is climate change occurring,” said Dennis Hamilton, chief of the Corps' project management branch. “But there isn't necessarily any complete agreement on how to deal with that for the purposes of river flooding.

“As it stands today, we're basically continuing to use the methodology developed in the mid-'70s. It basically assumes there isn't really any change in climate,” he said.

The Corps contends that Cedar Rapids' risk for catastrophic flooding is minimal, so the agency recommends more limited flood protection than city leaders want. But there's also the possibility that 2008 flood's ferocity is reflective of an altered climate. “If anything, the heavy rain events will be increasing,” said Gene Takle, a professor of meteorology at Iowa State. “It's a wake-up call.”

Takle says the biggest impacts here have been increased humidity and rainfall. Annual rainfall has steadily climbed in Iowa since the '50s, with the sharpest increase in Eastern Iowa. Since midcentury, Cedar Rapids has seen a fivefold increase in the number days with more than 1.25 inches of rainfall, or about what the ground can absorb.

Iowa now experiences more heavy rainfall events in the summer, Takle said, when weather patterns tend to spawn storms that move from northwest to southeast. That's the same directional orientation as most of our river basins, meaning a storm system has the potential to unload all or much of its water on a single watershed.

The Corps just completed a study of the Des Moines River and found that what was once considered a 100-year flood is now much more likely. A Cedar/Iowa River basin study is under way.

So we clearly need the whole enchilada flood projection system? Maybe. Takle also wrote in a report to the Legislature this month that some climate models expect the Midwest to dry out. But those models also may not have a good handle on the impact of climate changes.

Still, it would be irresponsible for local leaders to witness 2008's destruction and look at data collected by Takle and others and not pursue funding for a comprehensive protection system. No system can provide zero risk. But whatever the climatic causes, the ingredients for future flooding, perhaps severe flooding, appear to exist.

Maybe you don't want a 20-year sales tax, but residents of this town need to figure out how much risk they can live with.

Comments: (319) 398-8452; todd.dorman@sourcemedia.net