Flooding, sea-level rise could impact real estate value

For all its charm and beauty, Delaware was dealt a double whammy with its geology: not only is the First State bordered by a rising sea, the landmass is also slowly settling downward into the ocean. That’s why sea-level rise rates in the state are expected to double over the next century.

Delaware has already been studying the impact of a higher ocean level for years — not just for long-term effects, but for increased local flooding.

Now, that risk has shot back into the spotlight, with a new scientific report that suggests 24,703 Delaware homes worth $1.3 billion are at risk of inundation. That means the land would be completely underwater — though not necessarily the three-story house atop of that land — which generally means all practical access to the house is gone as well.

Using Zillow real estate data, the Union of Concerned Scientists considered three scenarios (high-, intermediate- and low-impact) over the next 82 years (through the year 2100).

Today, they suggest that 507 properties are already at risk.

According to those scenarios, at the intermediate risk level, Bethany Beach, South Bethany Beach and Fenwick Island alone would have a combined 13,000 properties at risk of chronic flooding in 2045.

“The results for Delaware are quite sobering,” the UCSUSA announced. “The analysis finds that without additional measures to adapt to rising seas, by 2045, nearly 6,000 of today’s residential properties, currently home to more than 7,000 people, are at risk of chronic inundation. The total number of at-risk residential properties jumps to roughly 24,000 — home to about 31,000 people — by 2100.”

That’s the highest risk scenario, which would impact $269 million worth of residential properties. That number jumps to $1.30 billion by the year 2100.

The study suggests the affected property is worth $4.6 million in annual property taxes (or up to $24 million in 2100).

Real estate is just one piece of the pie. Those figures don’t include rental or real estate transfer taxes; jobs that derive from real estate, hospitality or tourism; food and jobs derived from farming (if fields are inundated); public infrastructure; emergency services; or even mental health for the people forced to leave or adapt to a changing landscape.

Interestingly, it isn’t just the million-dollar beach houses at risk.

“In Delaware, nearly all (more than 98 percent) of the chronic inundation risk within the next 30 years is borne by residents of homes valued below the state median property value,” the UCSUSA stated. “Some of the most exposed places are also home to a large percentage of elderly residents, who may have more of their wealth tied to their property and could be more heavily affected by the erosion of the property tax base that funds community-wide services.”

They used data from multiple sources, including Zillow, NOAA and the 2014 National Climate Assessment. Those numbers aren’t perfect. The group used ocean-facing tidal gauges, which doesn’t include the impact of Delaware’s unique coastal features, including bays, inlets, wetlands and even bulkheads. They also didn’t assume any growth in population, nor any preventive measures communities might take.

The problem also doesn’t occur in a vacuum. The study included 22 states (plus D.C.). At the most, Delaware’s potential loss is less than 2 percent of the national’s total (and, often, it’s less than 1 percent). California and Florida lead the pack. Combined, half the time, those two states carry at least 20 percent of the total impact, and even 70 to 94 percent in a few categories.

Nationwide totals range from 138,394 to 2.39 million properties, in various scenarios. It would directly impact at least 272,628 people, and up to 4.7 million.

The most dramatic nationwide totals for lost market value —$912 billion or $499 billion in the high or intermediate risk scenarios, respectively — don’t even include the jobs lost if businesses, schools or nursing homes go (physically) underwater. Even if the maximum of 4.7 million people aren’t displaced, there still could be half a million people affected in the low-risk scenario.

Nearby, Maryland’s risk is 8,381 to 68,183 properties in various scenarios, with market values ranging from $1.9 billion to $21 billion and populations of 13,800 to 105,000 people impacted.

With the stakes that high, the group has encouraged adherence to international climate and energy agreements: “If nations adhere to the primary goal of the Paris Agreement — capping warming to below 2 degrees Celsius — and there is limited loss of land-based ice, about 74 percent of Delaware’s at-risk homes would avoid chronic flooding by the end of the century, thus safeguarding the vast majority of property values and annual property tax revenue,” the UCSUSA stated.

The full reports and data sets are online at www.ucsusa.org/underwater.


Delaware already 

having the conversation


Many Delaware officials are likely aware of the state’s vulnerability to the sea, although this study specifically highlights the risk to real estate.

Already, Route 1 closes near the Indian River Inlet when the ocean or bay floods the highway. Coastal towns suffer flooding during just mild storms and high tides. Nor’easters and hurricanes shred the coastline and flood along much of the state’s eastern reaches, along the Atlantic Ocean and Delaware Bay.

Based on 2007 maps, Delaware’s Sea Level Rise Advisory Committee estimated that between 8 and 11 percent of Delaware’s landmass would be inundated with water by the year 2100, which contains up to 5 percent of the state’s housing stock.

Sussex County’s 6 to 9 percent of land inundated would equal 3 to 14 percent of its housing stock. And with a basis of the 2007 maps, that doesn’t include the past decade of housing growth.

Delaware’s Sea Level Rise Advisory Committee was established by executive order in 2010 to identify what inundation (water on normally dry land) could do to the state. With that information, every state agency was directed to brainstorm adaptations for climate change, from heavier rain to longer droughts.

They used the three identified sea-level rise scenarios, of 0.5, 1.0 and 1.5 meters by the year 2100. (Based on more recent studies, scientists may update the numbers to 0.52, 0.99 and 1.53 meters, or roughly 1.7, 3.25 and 5 feet.)

The public can view the Delaware Coastal Programs online map viewer for a look at what sea-level rise and inundation could do to their neighborhoods, at www.dnrec.delaware.gov/pages/slrmaps.aspx.

By Laura Walter
Staff Reporter