New model adds human reactions to flood risk assessment

Researchers at North Carolina State University have created a land change model that simulates the interactions between urban growth, increased flooding, and how humans adapt in response. The new model could provide a more realistic risk assessment for urban planners, natural resource managers and other local government stakeholders.

“Traditional risk assessment typically involves overlaying flood layers – areas likely to be flooded – onto existing development or population distribution to identify areas and communities at risk,” explains Georgina Sanchez, a researcher at NC State’s Center for Geospatial Analytics and corresponding author of the work. “Yet this approach only provides a partial picture.

“Planners and residents are increasingly aware of the growing flood risks linked to climate change and are prepared to respond and adapt where they can,” says Sanchez. “It is crucial that models take into account our collective adaptation efforts, such as raising buildings or moving away from high-risk areas. Our model provides deeper insights, helping us understand adaptive capacities and identify resource-constrained communities – essentially characterizing the geography of impact and response.

The model, FUTURES 3.0 (FUTure Urban-Regional Environment Simulation), is an open source and scalable model that includes three components of flood risk: exposure, which refers to urban development patterns; risk, which includes increased flooding due to climate change; and the vulnerability, or adaptive response of people living in the area. The model integrates climate data as well as demographic, socio-economic and flood damage data.

The researchers used the greater Charleston (SC) metropolitan area as a test case. Charleston is a rapidly developing urban area located in a low-lying region bordered by the Atlantic Ocean and numerous rivers.

By comparing territorial change projections for 2035 and 2050 with a 2020 baseline and under various policy intervention and response scenarios, they considered possible demographic and population changes and identified the scenarios resulting in the least exposure to future flooding, as well as locations where the risk of flooding remained highest. across the landscape.

“The study highlights the importance of integrating human adaptive response to demographic changes and urban expansion for accurate exposure and risk assessment,” Sanchez said. “Not all residents or communities will have the means or capacity to put protective measures in place. Visualizing potential what-if scenarios helps us determine where and when impact occurs and understand who is affected and how.

The researchers’ next steps are to engage with communities to discuss potential interventions. They are also expanding their studies regionally.

“Through scenario-based modeling,” says Sanchez, “we explore questions such as: how will communities respond to damage, who has the means to adapt, and what challenges face those with resources limited to protect themselves?

“In addition, these scenarios allow us to visualize the long-term consequences of our current development choices,” continues Sánchez. “If we anticipate that in 30 years a newly developed community may be faced with the decision to opt out, why not think about protecting that area now?

The work appears in Scientific reports and is supported by the U.S. Geological Survey Southeast Climate Adaptation Science Center, the National Science Foundation’s Smart and Connected Communities Program, and the U.S. Department of Agriculture’s Intramural Research Program, National Institute of Food and Agriculture, McIntire-Stennis. The FUTURES open source software is accessible via the GitHub repository (https://github.com/ncsu-landscape-dynamics/GRASS_FUTURES) with the identifier doi:10.5281/zenodo.6607097.

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Note to editors: A summary follows.

“Spatially interactive modeling of land change identifies location-specific adaptations most likely to reduce future flood risk”

DO I: 10.1038/s41598-023-46195-9

Authors: Georgina M. Sanchez, Anna Petrasova, Megan M. Skrip, Elyssa L. Collins, Margaret A. Lawrimore, John B. Vogler, Jelena Vukomanovic, Helena Mitasova, Ross K. Meentemeyer, North Carolina State University; Adam Terando, North Carolina State University and US Geological Survey
Published: November 1, 2023 in Scientific reports

Abstract:
The impacts of sea level rise will last for centuries; therefore, flood risk modeling must move from identifying locations at risk to assessing how people can best cope. We present the first spatially interactive (i.e. what happens in one place affects another) land change model (FUTURES 3.0) that can probabilistically predict urban growth while simulating human migration and other responses to flooding, essentially describing the geography of impact and response. Accounting for human migration has reduced the total area of ​​developed land exposed to flooding by 2050 by 5 to 24 percent, depending on the area at risk of flooding (annual probability from 50 to 0.2 percent). . We simulated various “what if” scenarios and found that managed withdrawal was the only intervention with predicted exposure lower than baseline conditions. In the business-as-usual scenario, existing and future developments must either be protected or abandoned to cope with future flooding. Our open framework can be applied across different regions and advances local-to-regional efforts to assess potential risks and tradeoffs.