Spatial Characteristics of Urban Flooding from 2010-2017 through Citizen Science in Portland, OR

Authors

Katelyn Michelson - Portland State University, Heejun Chang - Portland State University

Body

Pluvial flooding is caused by intense rainfall events that overwhelm drainage systems and do not allow excess water to be absorbed by soils or water infrastructure. This type of flooding occurs frequently in urban systems and leads to public inconveniences and infrastructure deterioration. This study aims to examine the vulnerability of pluvial flooding in Portland, OR (2010-2017) by incorporating an interdisciplinary framework that examines the physical and socioeconomic vulnerability of flooding through citizen-reported flooding data. We use a spatially dense network of 5-minute interval rainfall measurement to examine 3-day storm events associated with flooding reports to correlate storm size with the frequency of reports. Results indicated that most citizens generated reports at 1 inch or less of rainfall, and were clustered in regions with high population density. Additionally, we identified the hot spots of pluvial flooding over space, and characterized the sociodemographic and building characteristics of hot spots by performing a spatial regression analysis using census tract level data. Results suggested that flooding reports were not clustered in regions with high sociodemographic vulnerability. Furthermore, communities of color and residents without a Bachelor’s degree were negatively correlated to flooding reports, while renters and residents with a median household income below 80% were positively associated with flooding reports. This research identified where pluvial flooding occurs across Portland, and how city planning can better address the biophysical and socioeconomic characteristics associated with pluvial flooding.
Keywords:urban flooding, participatory GIS, natural hazards vulnerability, voluntary geographic information

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