Ordinary policies achieve extraordinary climate adaptation
Consistently implementing zoning, permitting, and building regulations, all commonplace municipal tools, helped most New Jersey towns avoid floodplain development.
New Jersey is one of the most flood-prone U.S. states, and climate change is increasing the hazard by raising sea levels and supercharging severe storms like Hurricane Sandy. The state also faces pressure to develop new housing and infrastructure, often in low-lying inland and coastal areas that are the most vulnerable to flooding.
Despite this pressure, a recent analysis of new floodplain development found that 85% of New Jersey towns built relatively little in floodplains over the past 2 decades. Towns achieved this by applying routine land use management tools consistently over time, a slow but steady approach to climate adaptation.
"It's the 'eat your veggies' story," said study coauthor A. R. Siders, a climate adaptation researcher at the University of Delaware. To stay healthy, "for most people, the answer is 'eat your veggies, go to the gym.' For most towns, it's 'just use your zoning codes, use your regular local powers,'" she said.
Exceeding Expectations
The most effective way to avoid flood damage to homes and infrastructure is to avoid building in a floodplain. But as housing needs and industry growth increase development pressures around the United States, some communities might see floodplain development as their only option to meet demand.
Instead, recent research has shown that most U.S. communities limit floodplain development more than expected given how much developable land they have in a floodplain. Even some communities that sit mostly or entirely within floodplains built most of their new structures on non-flood-prone land
The researchers behind the nationwide study wanted to explore why communities avoided excessive floodplain development and how they did it. The team homed in on New Jersey, a state with both high flood risk and high development pressure that nonetheless did very well at avoiding floodplain development from 2001 to 2019.
Focusing on one state enabled the team to dive into the municipal ordinances and regulations that might have influenced development at the subcounty scale. They also interviewed local stakeholders and officials in four townships to get first-person accounts of what worked and what didn't for each location, as well as the capacity of each local government to implement change.
Four distinct flood development patterns emerged: rural river avoidance, exemplified by Lumberton Township; suburban coastal avoidance, exemplified by Aberdeen; wealthy waterfront development, exemplified by Weehawken; and multiple priorities with mixed outcomes, exemplified by Woodbridge.
In each of these case studies, the local government's capacity to govern (i.e., its funding, staff size, and mandate) could not fully explain how the townships avoided floodplain development.
"If a town has a zoning code but they don't enforce it…then just having it on the books isn't enough," Siders said.
What's more, several local officials told the researchers that introducing new plans, legal innovations, or politically motivated strategies could significantly set back a community's progress and lead to more floodplain development.
What did work? Local officials emphasized that commonplace regulations, implemented consistently over time, worked best. Two state officials described Lumberton and Aberdeen as "not doing anything special" or "not above and beyond," yet both townships built far less housing and infrastructure than expected in at-risk areas given their share of land in floodplains.
No single plan, regulation, policy, or program worked effectively for every community, as each township has specific needs and challenges. But a tailored combination of existing policies on zoning, land acquisition, buffer zones, permitting, and building codes-"a few good tools," officials described-implemented consistently over several years was often effective at reducing floodplain development.
The takeaway, Siders said, is that although floodplain development is still happening, it's not happening as much as you'd expect. "And it's possible to just do better, not with some crazy, Herculean efforts, but with, at least in most places, moderate increases in implementation," she said.
The analysis was published in Oxford Open Climate Change.
Adapting to the "New Norm"
"New Jersey is one of the most densely populated states in the nation," said Lisa Auermuller of Rutgers University in New Jersey, who researches coastal transformation. It's also one of the first states projected to develop all of its developable land, she added. Auermuller, who was not involved with the new research, said that "the findings match my own knowledge and observations" in that most New Jersey towns have strict floodplain regulations and work to avoid developing in those areas.
"Coastal flooding comes in many shapes and sizes," Auermuller added, from tide-driven nuisance flooding to storm surge to sea level rise. "The communities in coastal New Jersey have started to appreciate all these different types of flooding."
"Some of these findings match what we've observed in our buyout work," wrote Nick Angarone, New Jersey's chief climate resilience officer, and Courtney Wald-Wittkop, buyout program manager for New Jersey's Blue Acres program, in a joint statement provided to Eos. Blue Acres helps New Jersey residents with flood preparedness and recovery, including by buying properties that repeatedly experience flooding to encourage homeowners to move to lower-risk areas.
In the township of Woodbridge, for example, a zoning change "discouraged significant investments into an area identified for managed retreat," Angarone and Wald-Wittkop wrote. The change created open space in a neighborhood that had frequently flooded and helped residents relocate.
However, they cautioned that the floodplain maps the researchers used, which were defined by the Federal Emergency Management Agency (FEMA), don't give a complete picture of the state's flood hazard. Those maps don't account for the state's stormwater management challenges or updated subsidence calculations, they wrote, and therefore underestimate flood risk.
"Adapting to flooding being part of life is the 'new norm' in coastal New Jersey."
This study focused mainly on local ordinances and policies as drivers of development management, but Angarone and Wald-Wittkop also pointed to New Jersey's wetland preservation efforts. "State level efforts like these have influenced local decision making and contributed to reducing development in floodplains."
Siders and her colleagues acknowledged that their analysis considered only new development, not redevelopment such as tearing down older structures to build new ones in the same place. Many coastal suburban towns avoided new floodplain development but allowed redevelopment.
Though this may decrease the damage risk thanks to updated building and construction practices (e.g., higher base elevation, vents, or permeable construction materials), it keeps people and capital in areas that are facing increasing flood risk. Future analysis could assess redevelopment in flood-prone regions, too.
"Post-Sandy, coastal New Jersey does look different, but it is not because there is now less development in coastal floodplain," Auermuller said. "The rebuilt homes are higher but larger, and the coastal real estate is still at high demand and even higher prices. Adapting to flooding being part of life is the 'new norm' in coastal New Jersey."