Socially Vulnerable People and Stormwater infrastructure: A Geospatial Exploration of the Equitable Distribution of Gray and Green Stormwater Infrastructure in Washington D.C.

Abstract

Abstract Historically, hazard literature has used social vulnerability to describe how social stratification, based on race, income, education, gender, and other factors, differentially affects the risks and impacts that a given community experiences in a disaster event. Disaster literature also indicates that racially or socially marginalized communities often live in environments that have inadequate protective measures in place against disasters. Recent studies exploring green stormwater infrastructure (GSI) distribution from the perspective of environmental justice show that a high distribution of GSI, which can mitigate the impacts of flooding, significantly correlates with better-resourced communities. However, those studies do not show whether marginalized communities with less access to protective GSI are socially vulnerable or whether the vulnerable communities are relatively excluded from the flood mitigation benefits of stormwater infrastructure, linking the distribution of infrastructure only to specific socio-economic factors. Expanding the Pressure and Release (PAR) model of hazards and social vulnerability, this study explores the relationship between community social vulnerability and grey and green stormwater infrastructure distribution in Washington, D.C. by analyzing the correlation between social vulnerability indices, landscape and urbanization factors, and stormwater infrastructure capacity. The analysis reveals that both grey and green infrastructure capacity has statistically significant negative correlations with population density, imperviousness rate, and social vulnerability, suggesting that grey and green infrastructure is not equitably distributed throughout the city and that the areas of DC housing communities most vulnerable to disaster are those least served by DC’s grey and green infrastructure. Our findings show that the infrastructure separation from planning could raise an equity issue in terms of flooding and give support to the role of infrastructure as a mechanism that deepens social vulnerability. These findings require a broader role of planning that includes urban infrastructure elements and more collaborative works with engineers.