A compilation by the National Science Foundation of more than 8 million hydrologic measurements and construction histories in the Mississippi/Missouri River system, showed that flood levels rose in some cases more than 10 feet where dikes and levees were built, even as river flows in other areas remained the same. That data confirms warnings of those who say navigational structures built to channel rivers actually increase flood risk by restricting their flow in the wrong places.
In the St. Louis district, the U.S. Army Corps of Engineers this year began deploying new weirs and wing dikes that critics warned would increase flood risk for the area. In a paper this March, local professors said building those structures in the Mississippi would worsen a growing problem and is akin to pointing loaded cannons at St. Louis and East St. Louis. The implication is that those "cannons" would go off during the next big flood.
As flood waters inundated parts of Missouri this spring with unprecedented river levels, St. Louis and East St. Louis survived the onslaught, probably because of dozens of levee breaks upstream that reduced the water's volume. Upstream levee breaks may have inadvertently saved the St. Louis area and could hold clues for future river management.
Upstream solutions may be key to flood management as predictions of a warmer climate, less snow and more rain make new and better approaches a necessity.
Bob Freitag spent three decades working for the Federal Emergency Management Agency and now teaches University of Washington students how to design communities to withstand floods. Freitag and other forward-thinking people urge progressive mitigation strategies that create natural storage areas to alleviate flood effects on population centers, and in time, lower flood control costs.
Broadening flood control strategies could include natural solutions, such as rehydrating upper watersheds with trees to create natural sponges so there's less runoff; using natural anchors in upper reaches of rivers to slow the flows; and broadening levee systems in upper watersheds to reduce the river's energy before it reaches major population centers.
The Army Corps of Engineers has a big job ahead. Providing it gets the money it needs from Congress, the corps must inventory thousands of levees nationwide, assess their stability and fix those most in danger of failure.
The corps should invite input from outside scientists to help develop sound strategies nationwide on how communities can live with flooding. A growing body of evidence shows there are better ways to handle flooding than the traditional ones. With aging levees and a warming climate, it's time to consider new, progressive ideas in river engineering.
