East Portland with neighborhoods along I-205, pictured here, emerged as the city's multi-hazard hotspot. A Portland State study found that high-risk areas are marked by lower median incomes, lower education levels and higher racial diversity. (PC: City of Portland Flickr)
When it comes to compounding natural hazards like landslides, wildfires, flooding and extreme heat, where you live makes all the difference. New research from Portland State University underscores this disproportionate reality, finding that in Portland, the areas most vulnerable to multiple climate hazards are historically underinvested neighborhoods marked by lower median incomes, lower education levels and higher racial diversity.
The study — led by Justin Huber, a doctoral student in the Earth, Environment & Society program, and Heejun Chang, a professor of geography — mapped where hazards are most likely to hit across Portland and how those risks align with factors like income, education, tree cover, wetlands and access to critical services.
By examining social, ecological and technological variables, the researchers sought to better understand how natural hazards interact with the complex dynamics of urban systems.
"We're not just people experiencing natural hazards, but we're in a system that interacts with the natural hazards and the things we do also influence the potential for those hazards," Huber said. "If we cut down a bunch of trees, that may increase the likelihood of landslides but decrease the likelihood of forest fires."
Looking at individual hazards, flood and heat risks were more common in flat East Portland, while wildfire and landslide risks were more concentrated in the hilly terrain of West Portland.
When these threats overlap, though, East Portland emerges as the city's multi-hazard hotspot, with neighborhoods along I-205 scoring among the highest for all four hazard risks. These areas are home to a higher proportion of non-white residents, lower median incomes and lower educational attainment, according to the study. The inverse is often true of Central and West Portland, where overall hazard exposure is much lower.
Map showing census block groups (left) and census tracts (right) in Portland facing the highest risk from three or more hazards.
The high-risk areas are the same areas that have dealt with chronic underinvestment, the researchers said. Most of East Portland near present-day I-205 was labeled "definitely declining" — the second lowest rating — on the 1938 Home Owners' Loan Corporation maps that institutionalized redlining. In recent decades, as historically redlined but lower-risk neighborhoods in North/Northeast Portland underwent redevelopment, rising housing costs forced residents out to the more hazard-prone neighborhoods of East Portland.
"It's important to see how people move when these other two things — ecological and technological variables — change," Huber said. "You don't want to inadvertently cause people to move."
Key findings from the study include:
- Roughly 5% of Portland residents live in neighborhoods facing the highest risk from three or more hazards.
- Compared with the citywide average, those 18 census block groups — neighborhood-level areas typically home to 600 to 3,000 residents each — have lower median incomes, lower educational attainment, fewer wetlands and longer distances to hospitals.
- Areas with overlapping high hazard potential saw their median income grow the slowest over a 10-year period. They also had lower than average percent of residents with at least a bachelor's degree and higher than average percent of residents with a disability.
"Even though the city is trying to do some equity work, we have a long way to go," Chang said. "These hazard hotspots are the areas where the city can do better in creating more green and blue spaces and invest in infrastructure to make them more resilient to future hazards."
The researchers say the study can be replicated in other cities facing similar hazards from climate change and land development — not only for city managers to be better informed, but for residents living in those high-risk areas to be educated and empowered to advocate for better environmental infrastructure.
Accounting for overlapping hazards can dramatically improve emergency planning, the researchers said. For example, cities could use multi-hazard maps to better position evacuation routes and ensure critical infrastructure like hospitals is built in lower-risk areas so they can remain operational during a disaster.
Natural features can also serve as buffers. Expanding wetlands, or blue spaces, for example, helps absorb floodwaters, cools surrounding areas and blocks fires from moving across the landscape. Chang pointed to the Foster Floodplain Natural Area in Portland's Lents neighborhood, completed in 2012, as a good example of the city buying property from more than 60 homeowners to let Johnson Creek safely overflow and store floodwaters.
"Those are the kinds of efforts that this study can inform," Chang said.
The findings were published in the journal Natural Hazards. Funding for the study came from the National Science Foundation research traineeship at PSU focusing on the causes, consequences of and community responses to cascading natural hazards.