“People generally do a lousy job of acting on information, particularly statistical information,” said Rob Moore, a senior policy analyst who studies flooding at the Natural Resources Defense Council. He said there’s a difference between buying a home that has a 1 percent chance of flooding each year vs. knowing a home has flooded three times in the past five years. Nicholas Pinter, a professor and director of the University of California at Davis Center for Watershed Sciences, says in addition to the well-known bureaucratic delays that come with updating FEMA’s flood maps, they only tell people whether they’re in or out of a flood zone, rather than showing the risk gradients.

Currently, she said, the nation has a patchwork of disclosure laws in different states that often don’t take into account future flood risks. FEMA’s flood maps are often outdated and incomplete, she said, and many states don’t require property owners to disclose the flood history information to prospective buyers. “This is not a consumer-friendly world we are talking about,” she said. The real estate industry, for example, hasn’t always welcomed increased flood disclosures, due to concerns that they could slow sales or cut property prices.

For example, to determine changes to storm surge flooding over time, the model incorporates an MIT analysis of 50,000 synthetic hurricanes. And to find the historical flood risk for a specific property, the First Street re-created the extent of flooding from 50 historical river and storm surge events to find homes that flooded from a specific storm.