The Illusion of Flood Control
Scientific American Download time: May 20 2011 9:09 AM ET
My hometown lies on a sandbar, squarely in the floodplain of the Upper Mississippi River. Winona (Minnesota) benefited from its position along the river, rapidly growing to wealth as a steamboat port and lumber town. The second railroad bridge across the Mississippi was built there, and in 1900, Winona had more millionaires per capita than any other town in the country. In the last hundred years, the lumber industry in Winona has declined, but my town is still a major port on the Upper Mississippi and the river is the lifeblood of the community.
But the same river that gave so much to my hometown also wrought destruction on Winona. From its founding in the 1850's through the 1960's, parts of Winona were repeatedly inundated by spring floods of the Mississippi River. Record flooding occurred in April 1965, and disaster in Winona was averted only by frantic sandbagging and the mysterious blow-out of a railroad dike a few miles downstream that released floodwaters into a wildlife refuge.…