Dead and Buried: The potential impact of stream and wetland destruction on flood risk in historically redlined neighborhoods

Keywords: Redlining, Detroit, Flood Risk, Stream Burial, Wetland Burial
Abstract Type: Poster Abstract

Abstract

The United States government sponsored the Home Owners Loan Corporation (HOLC) in the 1930s to assess and grade urban neighborhoods based on perceived financial risk. The grades were influenced by the presence of minority racial groups, immigrants, and residents with lower socioeconomic statuses and, even though the practice was eventually outlawed, the impact on low income and underrepresented minorities is still prevalent today. This study is designed around several questions about the environmental legacy of HOLC in Metro Detroit, MI (USA): (1) Is flood risk disproportionately affected in areas graded as “hazardous” by the HOLC? and (2) Is flood risk higher in areas where streams and wetlands were buried / removed? Flood risk data, acquired from First Street Foundation’s Flood Factor dataset, was summarized by HOLC grade, and buried streams and wetlands were digitized from historical maps and also aggregated by HOLC grade. The results show flood risk is higher in C and D graded neighborhoods, compared to A and B. Regardless of HOLC grade, neighborhoods in close proximity to the Detroit River and Lake St. Claire have 10 times higher flood risk than inland neighborhoods. Interestingly, B-graded neighborhoods exhibit minimal impact from buried rivers and wetlands, but that risk increases substantially if there is a history of stream or wetland burial within a neighborhood. Flood risk is disproportionately distributed, caused in part by outlawed, racist housing policies. Understanding where risk is highest can help identify optimum locations for adaptation measures to minimize flood damage in these neighborhoods.