Urban Flood Risk and Green Infrastructure: Who is exposed to risk and receive benefits?: A case study of three US cities

Authors: Arun Pallathadka*, Portland State University, Jason Sauer, Arizona State University, Heejun Chang, Portland State University, Nancy Grimm, Arizona State University
Topics: Water Resources and Hydrology, Urban and Regional Planning, Hazards and Vulnerability
Keywords: Green Infrastructure, Pluvial Flood Risk, Urban Flooding
Session Type: Virtual Paper
Day: 4/7/2021
Start / End Time: 11:10 AM / 12:25 PM
Room: Virtual 6
Presentation File: No File Uploaded


Pluvial flooding is a serious hazard in Inland U.S. cities, as it is globally. Several flood mitigation techniques exist, one of which is Urban Green Infrastructure (GI), which is designed to store storm runoff or facilitate infiltration. This research explores the relationship between pluvial flooding and GI in three inland cities - Atlanta, Phoenix, and Portland - and further analyzes the underlying ethnic and racial minorities’ composition in the census block groups (CBG) of urban pluvial flood zones. Using data from high-resolution Digital Elevation Model (DEM), we derived blue spots for each CBG expressed in % area. We related it to the density of urban GI in each CBG, and created four classifications: i) Managed (High Blue spots, High GI), ii) Prepared (High GI, Low Blue spots), iii) Vulnerable (High Blue spots, Low GI), and iv) Least Concern (Low Blue spots, Low GI). Then, using the 2010 & 2018 American Community Survey (ACS) and historical GI data, we analyzed the temporal aspect of the size and distribution of ethnic and racial minorities as well as the urban GI in CBGs. Results shed light on social equity from an urban planning context. In Phoenix and Portland, GI is distributed in an equitable manner. GI is not distributed equitably in Atlanta, and that its relative absence in communities of racial and ethnic minorities increases their risk of exposure to pluvial flooding. The results reinforce the need for environmental justice in planning urban flood mitigation strategies.

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