As of Wednesday, the Midwest was getting another dose of deeply unwelcome rain to add to its current surfeit. While Missouri braces itself for yet more trouble, Iowa has at least been able to start its cleanup. One thing is certain, however: this isn't going to be the last flood the region experiences, nor will it be the worst. Mother Nature isn't that kind.
According to Richard Mertens' article in the Christian Science Monitor, "Why Floods Are Getting Worse" we haven't seen the last of this kind of flooding. We keep building in floodplains (mostly because it's cheap and partly because it's pretty), we erect levees to protect areas from floods but these can exacerbate flooding elsewhere, and we make sure that our fields drain quickly, which increases the speed at which runoff hits the waterways. We've also paved over a bunch of ground for roads and parking lots and subdivisions, converting it from a material that can absorb excess water into terrain that acts like a water speedway. The problem (as I understand it) isn't just the sheer quantity of rain, it's that we've removed a lot of natural safety-valves (such as wetlands and natural floodplains), which has the effect of funneling the rainfall into the rivers and streams far more rapidly than ever before. If the pressure can't be released upstream, then the problem moves downstream, with predictable results.
Because I was living in Iowa City during the 1993 floods, I've been watching the news coverage of the flooding in Iowa with great attention. The U.S. Geological Service maintains an excellent page listing a cornicopea of information about the Iowa floods, including information on stream gauges, precipitation forecasts, and links to satellite imagery-and kudos to the USGS personnel who kept the stream gauges up and working in difficult conditions. For a wider view what's happening with our water, check out the USGS's Real-Time Water Data for the Nation page.
It seems fairly clear to me that we need to change both the way we plan for floods and how we mitigate their effects. In the wake of Hurricane Katrina, the New York Times ran an excellent article ("In Europe, High-Tech Flood Control, With Nature's Help") discussing the various approaches either being used or under development around the world to deal with flooding.
Sensors installed along streams and rivers and instrumentation on levees and bridges can provide data to help shape our responses. However, I suspect the best approach combines technology with the water control tricks the planet has been using for millennia.