In Virginia Beach, the largest city by population in the Commonwealth of Virginia, the sea is rising about twice as fast as the global average. Since the 1960s, according to planning documents, the level has risen by about a foot, and the city already loses about $12 million a year due to damages from urban flooding. The rate of sea-level rise is in the top ten percent of cities in the United States, and officials are planning for an additional 1.5 feet of sea-level rise within the next 20-40 years, and up to 3 feet in the next 50-70 years.
But despite the city’s location on the Atlantic coast, Deputy City Manager Tom Leahy, says it’s the inland waterways — the Lynnhaven River estuary system, Back Bay, and Albemarle Sound, among others — that cause most of the challenges. The city is mostly flat, with a lot of land subsidence and high groundwater. Strong winds can be as problematic as storm surges.
“It’s just not as simple as, ‘Okay, here’s how high the ocean’s gonna be — let’s build a barrier,’” Leahy says.
Last week, the Virginia Beach city council received a draft of a Comprehensive Sea Level Rise/Recurrent Flooding policy report, in the works since 2015, that lays out a range of strategies for mitigating the consequences of rising seas. Without action, according to a presentation from Dewberry, the firm contracted to compile the report, annual losses could rise to $271 million with an additional three feet of sea level rise — about 23 times greater than current annual losses.
The draft report also identifies seven “focus areas for adaptation,” and lists dozens of recommended actions: Updating land-use plans, expanding education efforts, updating vulnerability assessments for critical infrastructure and transportation routes, retrofitting or relocating existing assets, issuing bonds to invest in resilience projects, creating guidelines for developers to assess flood risk, and increasing incentives to build in “Strategic Growth Areas” located away from the most flood-prone parts of the city.
The recommendations are ranked by priority levels. Not all of the policies will be implemented, Leahy says.
“We don’t just slap the report down and then say, ‘Okay, adopt this,’” Leahy says. “We’ve got to discuss it with council and discuss it with stakeholders and work our way through … This is where the results are starting to be put forth to show the public and show our council and start getting feedback on what the council and the public wants to do — and is willing to do — with respect to sea-level rise and coastal flooding.”
The city has already begun incorporating sea-level rise concerns into its infrastructure upgrades, Leahy says, rerouting roads and modifying bridges based on the latest projections. It also rebuilds between five and ten of its 400-some sanitary sewer pump stations a year, and has started relocating or raising some of them to keep them from being compromised by higher waters.
The report also recommends preserving existing tree canopy to help manage floodwaters in the city. Since December, a team of researchers in Virginia Tech’s Department of Forest Resources and Environmental Conservation has been working on a study, with support from Dewberry, that will monitor how much water is captured, stored, and removed by forest ecosystems in the city.
“We know from studies in many different geographies that forests reduce runoff,” says Brian van Eerden, director of the Virginia Pinelands Program at The Nature Conservancy, which commissioned the study alongside the city of Virginia Beach, Lynnhaven River NOW, and the Virginia Department of Forestry. “What we don’t know, and what the study is going to determine, is the magnitude of the flood-risk reduction that the forest cover in Virginia Beach is contributing now.”
Forests include wetland features that capture excess water, says Daniel McLaughlin, an assistant professor of ecohydrology at Virginia Tech, who is leading the study. And trees help remove water from the soil and surface back into the atmosphere through a process called “evapotranspiration.”
Researchers are planning to gather existing topographic and soil data and develop a model to estimate the total water storage and removal capacity of forests in Virginia Beach. That information can then be used by the city to prioritize forest conservation in areas that provide the greatest flood-mitigation benefits. (The researchers hope to create a tool and an interface that can be used with similar existing datasets in other cities, McLaughlin says.)
The draft policy report compiled by Dewberry also recommends that the city expand its programs to voluntarily acquire private property in strategic areas, including undeveloped parcels in wetland areas and floodplains. The Virginia Tech study could also help the city prioritize which properties to try to protect.
Leahy notes that the costs associated with implementing all the recommendations in the draft report run into the billions. But the report also makes clear that the cost of intervention is much lower than the losses would be if the city were to do nothing.
“This flooding issue is not something that’s going to be resolved tomorrow,” Leahy says. “It’s a fifty-year issue, and the key to solving fifty-year problems is to just get moving and never stop and never go back.”