Rising to the Challenge

For people whose business is to worry about flooding, there's no debate the Federal Emergency Management Agency (FEMA) needs to keep its flood maps current. But as Congress discusses the future of the National Flood Insurance Program (NFIP), not everyone agrees on the best way to modernize those maps or pay for the effort.

Congress created the NFIP in 1968 to reduce disaster assistance costs after floods by providing insurance on properties that are at high risk of flooding, so fewer owners will need government aid. The program also helps state and local governments manage floodplains so fewer properties are constructed in the way of rising waters. To support those two goals, FEMA works with state and local governments across the U.S. to map floodplains.

FEMA's Floodplain Insurance Rate Maps (FIRMs) indicate Special Flood Hazard Areas (SFHAs) - terrain where, in any given year, the chance that a stream will inundate the land is 1 percent or more. Anyone seeking a federally insured mortgage on a property in an SFHA must have flood insurance, which the NFIP subsidizes.

Insurance agents and lenders use FIRMs to determine which properties require the insurance. State and local governments use them in development planning and flood mitigation programs. Unfortunately in a community with ongoing development, the job of mapping the floodplain is never done.

"As farm fields and forests are turned into rooftops and parking lots, it destroys trees," said Larry Larson, executive director of the Association of State Floodplain Managers (ASFM) in Madison, Wis., adding that with fewer roots to drink up the water, more water runs into the nearest stream. "The flood level of that stream may go up significantly. As it does, the boundary of the 100-year floodplain expands to embrace more properties."

Homeowners continuously complain that their maps are obsolete, said David Maune, senior project manager for remote sensing at Dewberry, a Fairfax, Va. planning, design and program management firm whose expertise includes geographic information.

"I think something like 25 to 30 percent of flood claims are from people outside the special flood hazard areas," Maune added.

This creates a problem because many of these people don't carry flood insurance since, according to the FIRMs, they don't need it.

Funding Running Out
For a long time, FEMA had only $50 million per year to produce and update flood maps, Larson said. In 2003, Congress boosted that budget to $200 million a year, but only for the five-year period ending in 2008.

"Unless some additional authorization and appropriation is provided, FEMA will drop back to that $50 million a year," Larson cautioned, "and once again our maps will quickly become outdated."

A bill introduced in the U.S. House of Representatives in March proposed raising that funding to $400 million per year for fiscal 2008 through 2013. The Flood Insurance Reform and Modernization Act of 2007 directs FEMA to establish an ongoing program to review, update and maintain the FIRMs.

Among other items, it also requires FEMA to raise the NFIP's insurance coverage limits; phase out insurance subsidies for vacation homes, second homes and nonresidential properties; and submit annual financial reports on the NFIP.

Although FEMA ultimately is responsible for keeping flood maps current, state and local governments, working with private-sector partners, do the bulk of the work and share the costs with the federal government, Larson said.

When engineers study updating the FIRMs, hydrology and hydraulics receive significant attention. The first asks, "If X inches of rain fall, what volume of water will that add to the local stream?" The second asks, "When you add that volume of water, how high will the stream rise?"

A third factor is land elevation, or topography. Topography matters because, for example, if a house stands atop a knoll that puts it 10