An aerial view of homes in Westhampton, New York with...

An aerial view of homes in Westhampton, New York with flooded lawns from the high tide in Shinnecock Bay caused by superstorm Sandy on Oct. 30, 2012. Credit: Newsday/Doug Kuntz

Flooding, the costliest and most common disaster in the United States, leaves no part of the country untouched: from nor'easters along the coast of Maine, to king tides in Florida, to overflowing rivers in Nebraska, to mudslides in California. After a "bomb cyclone" swamped the Midwest recently, the National Oceanic and Atmospheric Administration warned that this spring might be "an unprecedented flood season," putting 200 million Americans at risk. Images of entire cities underwater, boats floating down interstates and bridges washed away capture the public's attention. Despite the frequency of floods, dangerous myths persist, shaping how we prepare and respond to them. Here are five.

Myth No. 1: Floods are "natural" disasters.

Flood disasters are inevitably referred to as "natural." See, for example, this headline from the Atlantic, about the 2016 flooding in Louisiana: "America Is Ignoring Another Natural Disaster Near the Gulf." Or from the Los Angeles Times in 2017: "Harvey is likely to be the second-most costly natural disaster in U.S. history." And this month, Gov. Pete Ricketts called the flooding in Nebraska "the most widespread natural disaster in our state's history."

But disasters are created by the interaction of a hazard and our communities. It may be natural for heavy rainfall or snowmelt to cause rivers to overflow their banks, but the actual destruction that results - damaged infrastructure, destroyed homes, ruined crops, washed-away topsoil - is a result of human behavior. Human activities destroy natural flood protection and put more people in harm's way. When forests are cut down and bayous paved over to make way for development, it exacerbates a community's overall flood risk.

And our efforts to prevent flooding can actually worsen it: Analyses by geologists at the University of California at Davis found that new levees along the Mississippi River made floods more frequent and more severe - spurring the construction of even more protective levees, and leading to a "hydrologic spiral."

Myth No. 2: Homeowner's insurance covers flood damage.

Finding out your homeowner's insurance doesn't cover floods is an unwelcome surprise when you're standing in the middle of your inundated living room. After Hurricane Sandy, some New Yorkers discovered that their homeowner's insurance would not pay for flood damage: "They're covering five shingles and a piece of gutter, and that's it," one told a Reuter reporter. Similarly, after flooding hit Iowa in 2018, an employee with the state's insurance regulator told the Des Moines Register that he'd been fielding calls from residents with homeowner's insurance who had not realized it didn't cover sewer backups. "Now that they have reached out to their insurance company, they're finding no coverage was afforded for that," he said.

After Hurricane Irma, Robert W. Klein, a professor at Georgia State University, told the Atlanta Journal-Constitution: "A lot of people just don't know their homeowners won't cover them for flood. Howard Mills, a former New York insurance commissioner,said in the Wall Street Journal: "Even financially literate people do not understand that the standard homeowners policy does not cover flood."

Nearly all home insurance policies exclude floods. When widespread flooding nationwide in the early 1900s overwhelmed private insurance agencies, they stopped offering flood coverage. In 1968, in an effort to fill the gap, Congress created the National Flood Insurance Program (NFIP). It is now the primary source of flood coverage for the United States, with more than5 million policies issued in 2018. This covers only a fraction of people who might need it. In Southeast Texas, which has relatively high rates of NFIP enrollment, 80 percent of residents were uninsured during Hurricane Harvey.

Myth No. 3: A "100-year flood" is a historic, once-in-a-century disaster.

Describing floods in terms of "100-year," "500-year" and "1,000-year" often makes people think the disaster was the most severe to occur in that time frame - as encapsulated by President Trump's tweet calling Harvey a "once in 500 year flood!" He's not alone. When researchers from the University of California at Berkeley surveyed residents in Stockton, Calif., about their perceived flood risk, they found that although 34 percent claimed familiarity with the term "100-year flood," only 2.6 percent defined it correctly. The most common responses were some variation of "A major flood comes every 100 years - it's a worst-case scenario'' and ''According to history, every 100 years or so, major flooding has occurred in the area and through documented history, they can predict or hypothesize on what to expect and plan accordingly and hopefully correct."

In fact, the metric communicates the flood risk of a given area: A home in a 100-year flood plain has a 1 percent chance of flooding in a given year. In 2018, Ellicott City, Md., experienced its second 1,000-year flood in two years, and with Harvey, Houston faced its third 500-year flood in three years.

That risk constantly changes, because of factors such as the natural movement of rivers, the development of new parcels of land, and climate change's influence on rainfall, snowmelt, storm surges and sea level. "Because of all the uncertainty, a flood that has a 1 percent annual risk of happening has a high water mark that is best described as a range, not a single maximum point," according to FiveThirtyEight.

Myth No. 4: Looting is common after floods.

Perhaps one of the most persistent myths about flooding is that people often use the crisis as an opportunity to steal from empty homes and businesses. Former New Jersey governor Chris Christie told CNN to expect lawlessness during Hurricane Harvey: "Looting is going to come next . . . the bad elements that exist in every society and every state will try to take advantage of it." As Hurricane Florence made landfall in North Carolina, a local news outlet claimed that "looting is as common when hurricanes strike as high winds and flooding."

This myth partly stems from a misunderstanding of what "looting" means. There is a clear distinction between ransacking a jewelry store and taking emergency medical supplies from a pharmacy, and some reports of looting mistakenly describe the latter. "That's not looting; that's survival mode," a military official who oversaw the response to Hurricane Katrina told The Washington Post.

Decades of research has found that looting after disasters is extremely rare. In a study of 100 such events, Disaster Research Center experts found many stories and rumors about looting, but very few verified cases. Instead, people engage in pro-social behavior: They act rationally, even generously, to help one another.

This myth has dangerous consequences: It can deter people from evacuating their homes. In interviews with researchers, residents who refused to leave before Hurricane Andrew in 1992 and Hurricane Bonnie in 1998 cited the desire to protect their property as a reason.

Myth No. 5: Floods discourage people from building in risky areas.

A consultant in Florida who advises property owners on flood risks told Rolling Stone that "property buyers are getting smarter. They are moving to higher elevations, one foot at a time." In an interview with Yale Environment 360, marine scientist Orrin Pilkey predicted that "sinking prices will cause a dramatic reduction in new beachfront development nationwide." Commentator Ben Shapiro summed up attitudes held by many when he said, of sea-level rise: "You think people aren't just going to sell their homes and move?"

But our current approach to emergency management actually encourages people to rebuild rather than move. The Natural Resources Defense Council says that for every $100 the Federal Emergency Management Agency has spent to rebuild flooded homes, it has allocated only $1.72 to move people and buy out their properties. And residents aren't just staying put: People are moving to flood-prone areas. An analysis by the magazine Governing found that the population growth within 100-year floodplains was faster than in areas outside flood zones. And a report by Climate Central and Zillow found that in New Jersey, about 2,700 new homes, worth an estimated $2.6 billion rose in the flood-risk zone in 2009, "most likely driven by reconstruction following Sandy." This upward trend also held true in nine other coastal states: Construction growth in flood-risk zones outstripped growth in safer areas.

Samantha Montano is a visiting assistant professor in the Department of Emergency Management at North Dakota State University. She wrote this piece for The Washington Post.

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