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1. Recognizing flood exposure inequities across flood frequencies

   https://doi.org/10.1016/j.ancene.2023.100371  

   Selsor, Haley; Bledsoe, Brian P.; Lammers, Roderick (June 2023, Anthropocene)

   Urban flooding is a growing threat due to land use and climate change. Vulnerable populations tend to have greater exposure to flooding as a result of historical societal and institutional processes. Most flood vulnerability studies focus on a single large flood, neglecting the impact of small, frequent floods. Therefore, there is a need to investigate inequitable flood exposure across a range of event magnitudes and frequencies. To explore this question, we develop a novel score of inequitable flood risk by defining risk as a function of frequency, exposure, and vulnerability. This analysis combines high-resolution, parcel-scale compounded fluvial and pluvial flood data with census data at the census block group scale. We focus on six census tracts within Athens-Clarke County, Georgia that are highly developed with diverse populations. We define vulnerable populations as non-Hispanic Black, Hispanic, and households under the poverty level and use dasymetric mapping techniques to calculate the over-representation of these populations in flood zones. Inequitable risks at each census tract (approximately neighborhood scale) were estimated for multiple (e.g., 5-, 10-, 20-, 50-, and 100-year) flood return periods. Results show that the relatively greatest flood risk inequities occur for the 10-year flood and not at the largest event. We also found that the size of inequity is dynamic, depending on the flood magnitude. Therefore, addressing a range of events including smaller, more frequent floods can increase equity and reveal opportunities that may be missed if only one event is considered. 

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2. Framing the Problem of Flood Risk and Flood Management in Metropolitan Los Angeles

   https://doi.org/10.1175/WCAS-D-22-0013.1  

   Ulibarri, Nicola; Valencia-Uribe, Claudia; Sanders, Brett F.; Schubert, Jochen; Matthew, Richard; Forman, Fonna; Allaire, Maura; Brady, David (January 2023, Weather, Climate, and Society)

   Abstract This paper develops the concept of flood problem framing to understand decision-makers’ priorities in flood risk management in the Los Angeles Metropolitan Region in California (LA Metro). Problem frames shape an individual’s preferences for particular management strategies and their future behaviors. While flooding is a complex, multifaceted problem, with multiple causes and multiple impacts, a decision-maker is most likely to manage only those dimensions of flooding about which they are aware or concerned. To evaluate flood decision-makers’ primary concerns related to flood exposure, vulnerability, and management in the LA Metro, we draw on focus groups with flood control districts, city planners, nonprofit organizations, and other flood-related decision-makers. We identify numerous concerns, including concerns about specific types of floods (e.g., fluvial vs pluvial) and impacts to diverse infrastructure and communities. Our analyses demonstrate that flood concerns aggregate into three problem frames: one concerned with large fluvial floods exacerbated by climate change and their housing, economic, and infrastructure impacts; one concerned with pluvial nuisance flooding, pollution, and historic underinvestment in communities; and one concerned with coastal and fluvial flooding’s ecosystem impacts. While each individual typically articulated concerns that overlapped with only one problem frame, each problem frame was discussed by numerous organization types, suggesting low barriers to cross-organizational coordination in flood planning and response. This paper also advances our understanding of flood risk perception in a region that does not face frequent large floods. Significance StatementThis paper investigates the primary concerns that planners, flood managers, and other decision-makers have about flooding in Southern California. This is important because the way that decision-makers understand flooding shapes the way that they will plan for and respond to flood events. We find that some decision-makers are primarily concerned with large floods affecting large swaths of infrastructure and housing; others are concerned with frequent, small floods that mobilize pollution in low-income areas; and others are concerned with protecting coastal ecosystems during sea level rise. Our results also highlight key priorities for research and practice, including the need for flexible and accessible flood data and education about how to evacuate. 

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3. Spatiotemporal implications of flooding on relocation risk in rural and urban coastal municipalities

   https://doi.org/10.1016/j.landusepol.2023.106754  

   Bukvic, A.; Mitchell, A.; Shao, Y.; Irish, J.L. (September 2023, Land Use Policy)

   The research on coastal hazards predicts substantial adverse impacts of chronic and episodic flooding on populated coastal areas. Despite the growing evidence about anticipated flood risks, many coastal communities are still not adapting. The observed disconnect between science on physical impacts and adaptation decisionmaking in part reflects stakeholders’ inability to envision the implications of these impacts on socioeconomic systems and the built environment in their jurisdictions. This inertia is particularly apparent in the discourse on flood-driven displacement and relocation. There is a lack of knowledge about direct and indirect flood impacts on community attributes and services that contribute to relocation decision-making. This study holistically evaluates the flood exposure on municipal features vital for socioeconomic stability, livelihoods, and quality of life across spatiotemporal scales. As such, it uses a more nuanced approach to relocation risk assessment than those solely focused on direct inundation impacts. It measures flood exposure of land use, land cover, and sociocultural and economic dimensions that are important drivers of relocation in selected rural and urban areas. The approach uses a 50-year floodplain to delineate populated coastal locations exposed to 2% Annual Exceedance Probability (AEP) storm surge projections adjusted for 2030, 2060, and 2090 sea level rise (SLR) scenarios. It then evaluates the potential impacts of this flood exposure on different types of land uses and critical socioeconomic assets in rural (Dorchester and Talbot Counties, Maryland, USA) and urban (Cities of Hampton, Norfolk, Portsmouth, and Virginia Beach, Virginia, USA) settings. The results show that some urban land uses, such as open space, military and mixed-use, and rural residential and commercial areas, might experience significantly more flooding. There are also notable differences in the baseline flood exposure and the anticipated rate and acceleration in the future among selected communities with significant implications for relocation planning. 

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4. Reconceptualizing urban flood modeling: Toward intersectional and equitable urban flood risk planning

   https://doi.org/10.1016/j.scs.2025.106578  

   Scolio, Madeline; Amur, Achira; Olson, Emma; Smith, Virginia; Wadzuk, Bridget; Homet, Kate; Devlin, Eric; Kremer, Peleg (July 2025, Sustainable Cities and Society)

   Urban flooding, fueled by climate change and rapid urbanization, presents significant challenges for cities around the world. In the United States, this is of particular concern as we see older cities reaching their maximum development density, and newer cities developing to the edge of their boundaries. The dynamic nature of cities and the people that live in them complicate urban flood risk modeling. This paper highlights the need to reconceptualize urban flooding from a spatially and temporally intersectional perspective by analyzing the patterns of socio-economic and bio-physical data across eight US cities to illustrate how spatial flood risk is driven by place-specific factors. Here, we demonstrate the need for a holistic understanding of flood risk, which acknowledges both the deep histories and uncertain futures specific to each city to promote urban flood resilience and environmental justice. Legacies of racialized development continue to influence the spatial heterogeneity of urban flood risk. Thus, centering the ways past injustice has shaped the environment is critical to highlighting inequities in who and where is at increased risk of flooding. The varying impacts of climate change on flooding in different cities, as well as the actions city governments have taken in response to flood events, inform risk and should be included in modeling efforts. There are many challenges in incorporating new temporal dynamics into flood risk modeling, such as data availability, creating a necessity for a greater understanding of flood impact. This is required not only to fully comprehend the impacts of flooding but also to identify appropriate, necessary, and community-sensitive flood interventions as well as to optimize the impact of adaptive measures. Considering historical and future drivers of risk, intersectional flood risk models are required to promote more equitable and effective resilience efforts. This approach will allow urban flood planners and engineers to gain a deeper understanding of how to promote climate resilience while overcoming the reinforcement of discriminatory development and management patterns. 

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5. Effect of Compound Flooding on Performance of Earthen Levees

   https://doi.org/10.1061/9780784482797.069  

   Jasim, Firas H.; Vahedifard, Farshid; Alborzi, Aneseh; Moftakhari, Hamed; AghaKouchak, Amir (February 2020, Geo-Congress 2020: Engineering, Monitoring, and Management of Geotechnical Infrastructure, Geotechnical Special Publication No. 316)

   null (Ed.)

   Earthen levees protecting coastal regions can be exposed to compound flooding induced by multiple drivers such as coastal water level, river discharge, and precipitation. However, the majority of flood hazard analyses consider only one flood driver at a time. This study numerically investigates the performance of an earthen levee in Sherman Island, Sacramento, CA, under compound flooding induced by fluvial and pluvial flooding. A finite element model is built for fully coupled 3D stress-flow simulations of the levee. The finite element model is then used to simulate the hydro-mechanical response of the levee under different flood scenarios. Fluvial flood hydrographs for different scenarios are obtained using a bivariate extreme analysis of peak river discharge and peak ocean level while accounting for the significance of correlation between these two variables. Pluvial flooding is characterized using intensity-duration-frequency (IDF) curves of extreme precipitations for the study area. The fluvial and pluvial flood patterns for different recurrence intervals are used in the finite element model to simulate the hydro-mechanical response of the levee. Results show that considering compound flooding leads to 8.7% and 18.6% reduction in the factor of safety for 2 and 50-year recurrence intervals, respectively. 

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