Research & Commentary: Levees and Flood Mitigation

Published May 2, 2012

For more than a century, the United States has attempted to control water almost entirely with levees and other “structural” means. During that time the cost of flood damage has more than tripled in inflation-adjusted terms. Some critics of current flood control policies argue many states should move away from a heavy reliance on levees.

Levees are an important part of any flood mitigation program, and in many areas levees do need to be repaired. However, building and improving them cannot solve all flooding problems. Quite often, building levees to protect one area can make flooding worse in another. In many places, leaving flood plains in their natural state (or something close to it) can do more to protect inland residents than any amount of levee construction.

Most recently a variety of issues related to the imperfect protection that levees provide have come to the forefront. Many groups have brought up concerns over “residual risk”—risk that remains for properties behind levees. In general, environmental and free-market groups believe such risk should be identified and incorporated into insurance rates, while developers and many local communities argue ignoring the risk will best serve economic development interests. Some communities—East St. Louis, Illinois, most prominently—have had to confront problems stemming from “decertified” levees that still stand but do not provide as much protection as once believed.

With flood management systems nearing the end of their useful lives across the country, a closer look at the role of levees and their continued use in flood preparation is required. Although levees and dams will always be a part of the equation in managing flood waters, they cannot continue to be the primary focus.

The following articles examine the role of levees in flood management.

Should Metro East’s Economy Be Sacrificed For Lack Of A Collaborative Procedure? A Story Of Levees, Floods, FEMA, And Frustration
Arin Greenwood writes in Out of the Storm News about how the people of Metro East, Illinois are fighting FEMA’s decision to de-accredit their levees. Is there anything to their fight that the free marketers and the environmentalists would agree with? It turns out there is. 

Levees: The Double-Edged Sword
The Association of State Floodplain Managers examines the use of levees in current flood mitigation efforts and suggests how levees should be used, primarily as a last resort, in the future. 

The NFIP and Levees: FAQ
In this FAQ, the Federal Emergency Management Agency explains its role in the levee certification process and the importance of examining levees in determining an area’s flood risk. 

Flood Risk Perception in Lands “Protected” by 100-year Levees
Jessica Ludy and G. Matt Kondolf surveyed residents of a recently constructed subdivision in Stockton, California to assess their awareness of their risk of flooding. They found that despite the levels of education and income, residents did not understand the risks. The survey was conducted in response to an unusual situation in the Sacramento-San Joaquin Delta of California, where lands below sea level are not considered “floodplain” and are open to residential and commercial development because they are “protected” by levees. 

Estimating Potential Reduction Flood Benefits of Restored Wetlands
Kenneth Potter of the University of Wisconsin examines wetland restoration and whether restoring wetlands is an effective tool in flood mitigation. While agreeing with the concept, Potter contends current methods of measuring are unable to adequately determine the effectiveness of the restored wetlands. 

Mandatory Flood Insurance Purchase in Remapped Residual Risk Areas behind Levee
In this report to Congress, Rawle O. King of the Congressional Research Service examines mandatory flood insurance purchase requirements in remapped flood-risk areas. 

Levees—Taking the Long View
Patricia Skinner of the Risk Institute writes in the 2006 Risk Management Yearbook suggesting levees will provide better protection if we change the way we regulate and insure development in the areas protected by them. 

Moral Hazard in Action: Who Insures Against Floods and Why?
Writing for Consumers’ Research, John Hood explains how the National Flood Insurance Program can skew the perception of flood risk and thus induce homeowners to build in flood-prone areas, with disastrous results. 

Midwest Flooding Disaster: Rethinking Federal Flood Insurance
In another report to Congress, Rawle O. King of the Congressional Research Service reexamines federal flood insurance after the 2008 Midwest floods. He includes a discussion of levee failure and suggests several changes in levee policies.