Flooding is a natural hazard that touches nearly all facets of the globe and is expected to become more frequent and intensified due to climate and land-use change. However, flooding does not impact all individuals equally. Therefore, understanding how flooding impacts distribute across populations of different socioeconomic and demographic backgrounds is vital. One approach to reducing flood risk on people is using indicators, such as social vulnerability indices and flood exposure metrics, to inform decision-making for flood risk management. However, such indicators can face the scale and zonal effect produced by the Modifiable Areal Unit Problem (MAUP). This study investigates how the U.S. Census block group, tract, and county scale selection impacts social vulnerability and flood exposure outcomes within coastal Virginia, USA. Here we show how (1) scale selection can obstruct our understanding of drivers of vulnerability, (2) increasingly aggregated scales significantly undercount highly vulnerable populations, and (3) hotspot clusters of social vulnerability and flood exposure can identify variable priority areas for current and future flood risk reduction. Study results present considerations about using such indicators, given the real-life consequences that can occur due to the MAUP. The results of this work warrant understanding the implications of scale selection on research methodological approaches and what this means for practitioners and policymakers that utilize such information to help guide flood mitigation strategies.
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This content will become publicly available on June 1, 2024
Recognizing flood exposure inequities across flood frequencies
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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- Award ID(s):
- 2115293
- NSF-PAR ID:
- 10486971
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Anthropocene
- Volume:
- 42
- Issue:
- C
- ISSN:
- 2213-3054
- Page Range / eLocation ID:
- 100371
- Subject(s) / Keyword(s):
- ["Flood risk equity","Urban flood hazard","Social vulnerability","Environmental justice"]
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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