The research examined the long-term flood risk, probabilities of levee failures and resulting economic losses along the Mississippi River, but the science applies to levee systems worldwide.
"Every time an inch is added to the top of a levee, flood risk is moving from the location behind that levee, to other locations, opposite bank, upstream, downstream, and even to some residents within that levee system itself,” says Nicholas Pinter, lead author with the UC Davis Department of Earth and Planetary Sciences.
Pinter says levees built around the Natomas neighborhood in Sacramento were ill-advised.
“It was built for the purpose of encouraging construction, billions of dollars of construction. Most floodplain managers would say this is something that should not be done," says Pinter. "The profits are accrued by the developers. There is an increase to the local tax base, but the long-term risk is born by the residents and taxpayers statewide and nationwide.”
Pinter says levees are appropriate when they’re built to protect pre-existing, high-value, concentrated development – like downtown Sacramento. The study was published in the journal Environmental Science and Policy.