Delaware Public Media

Delaware builds more houses in coastal risk zones than in safer areas, report says

Aug 16, 2019

Despite years of warnings about the dangers of rising seas to its low-lying coast, Delaware is building homes in places that are vulnerable to higher seas and storm surge more than twice as fast as it is in safer areas, a new report says.


The national report from the research group Climate Central and the real estate company Zillow updates its estimates from less than a year ago by using more precise measurements of exactly which properties are in areas that are expected to be flooded in 30 years’ time.

In Delaware, the number of recently built homes at risk of flooding from a typical once-a-year storm was revised up to 962 from 771 in the last report in November 2018, based on projected sea-level rise by 2050. That means the First State has coastal property worth $638 million in those areas, up from $526 million in the earlier report.

Coastal property is being built in Delaware at 2.6 times the rate that is in safer areas, giving the state the fourth-highest rate of construction in so-called risk zones between 2009 and 2017.

“Across the United States, coastal communities have recently built tens of thousands of houses in areas at risk of future flooding driven by sea-level rise from climate change,” the report said. “That has put homeowners, renters and investors in danger of steep personal and financial losses in the years ahead.”

Even though the public is becoming more aware of sea-level rise and climate change, and despite the devastation caused to the Northeast by Hurricane Sandy in 2012, coastal development has continued unabated, some of it taking the form of post-Sandy reconstruction, the report said.

In a third of the country’s coastal states, the rate at which new homes are being added in risk zones exceeds the rate in areas that are not exposed to coastal flooding.

By many measures, Delaware’s coastal property is among the most exposed in the nation, the report said.

The state has the fifth-highest number of properties that would be flooded by 2050 based on predictions for the kind of storm that only occurs once every 10 years, the report said. By that measure, Sussex County has the third-biggest number of exposed properties of any county in the country: 1,233 worth a combined $855 million.

The projections are based in part on global sea-level forecasts by the UN’s International Panel on Climate Change, and different scenarios for cuts in global carbon emissions. If the world’s 197 nations make the moderate carbon cuts agreed at the Paris climate talks in 2016, then 2,241 new Delaware properties would be in the risk zone during a 10-year storm, the report said. But if carbon emissions go unchecked, that number would rise to 2,825.

By 2050, it won’t make much difference to the number of exposed homes whether the world makes deep carbon cuts or none at all, but by the end of the century, those choices will have a big effect on the number properties that will be underwater, the report said.

In Delaware, where official state forecasts anticipate sea levels will rise 1.3 feet by 2050, advocates for curbs on coastal development call for more education for county and local officials on the consequences of allowing construction in flood zones.

Danielle Swallow, a coastal hazards specialist with Delaware Sea Grant, said the local experience mirrors the national picture presented by the Climate Central/Zillow report.

“In my experience, there’s an under-developed sense of risk, and how one mitigates risk,” said Swallow, a co-founder of RASCL, a nonprofit that helps coastal communities plan for sea-level rise and climate change.

She said the increasing coastal construction partly reflects a complacency based on the fact that Delaware hasn’t recently suffered the full impact of a major storm like Sandy which devastated many shore communities in neighboring New Jersey.

But it also shows a need for more education for county and local officials on the consequences of allowing risk-zone development, she said.

Swallow rejected arguments by some local officials that requiring sufficient “freeboard” – the height of the bottom of a house above ground level – removes the risk of flooding.

Even if flood waters don’t enter elevated properties, they may still be cut off and lose their services during storms, she said.

“Some people think that just because they elevate a house, their risk goes to zero,” she said. “But they don’t take into account whether the roads leading to that house and into the neighborhood are accessible in a flood or a storm, whether their utilities are operable, or whether their car is going to float away. There are many aspects of community resiliency that don’t get factored in.”

Don Bain, a senior adviser to Climate Central, said simply elevating a building doesn’t remove buildings from future flood zones, or cushion their occupants from the consequences. He recalled a New Jersey family who sank their life savings into elevating their restaurant above the anticipated flood level, only to realize that their customers may not be able to reach during a flood.

And a coastal hospital built to avoid flooding isn’t going to succeed if doctors and patients can’t get there through flooded streets, he said.

In Delaware, Swallow declined to identify specific examples of new developments that have been built in harm’s way but said there’s plenty of evidence along the Delaware coast.

“If you look up and down the coast, you’re going to see subdivisions going up, often touting waterfront views and water amenities,” she said.

County and local planning authorities base their approval of such properties on FEMA flood maps that don’t include projections for sea-level rise, she said.

“They don’t include future conditions in land-use planning and master planning,” she said. “Right now, our flood zones, as defined by FEMA, are based on historical storm records but we know that our climate is changing, seas are rising, and storms are getting bigger and more frequent.

“If you build a subdivision, don’t build it to today’s standards, build it for the conditions in 30 years from now,” she said.

Delaware Nature Society also called for planning decisions to be based on anticipated future conditions, not current circumstances.

Laura Miller, a spokeswoman for the environmental group, urged municipalities to create climate action plans that identify specific local risks and propose ways of mitigating them.

Wilmington, a community that already suffers from flooding in some low-lying areas, offers a model for sustainable planning by having already met a 2020 goal for cutting greenhouse gases, increasing the energy efficiency of city buildings, and curbing stormwater runoff by reducing the amount of impervious surface, Miller said.

She urged other communities to implement such measures, warning of dire consequences for those that fail to do so.

“Delaying action on climate change will make our state more likely to lose income from economically productive areas due to property damage caused by flooding and disruption of commerce, and will cost more to repair flood-damaged areas than it would to protect them early on,” she said.