Flood Vulnerability Implications of an “Unmanaged” Relocation of Property Buyout Participants: Case of Harris County, TX

• In Event: Informing Disaster Risk Management: Analyses of Forecasting, Short-term Displacement, Public Disaster Assistance, and Long-term Relocation

Abstract

The increasing frequency and severity of flood events have heightened interest in local disaster adaptation strategies. Among these, managed retreat has become a critical approach for reducing flood risks in low-lying coastal areas, particularly where structural protection alone cannot prevent repeated losses. In the United States, retreat is typically implemented through government-led property acquisitions, or "buyouts," primarily funded by federal programs such as the Hazard Mitigation Grant Program (HMGP), the Flood Mitigation Assistance (FMA) program, and Community Development Block Grants (CDBG). 

Buyouts are voluntary; eligible homeowners can sell their properties at pre-disaster market value to a local public agency. Once acquired, the properties are demolished, and the land is preserved as open space in perpetuity. These programs offer significant social and ecological benefits, including reduced exposure to future flooding and the creation of environmental amenities and ecosystem services. However, limited oversight of where participants relocate may result in an unintended redistribution of risk. This "unmanaged" relocation, especially amid expanding floodplains due to changing precipitation patterns and seal level rise (SLR), can inadvertently create new areas of vulnerability, undermining the goal of long-term community resilience.

In this study, we examine buyout-induced relocations in Harris County, Texas, between 2010 and 2020. By tracking participants’ relocation, we compare origin and destination locations in terms of current social and flood hazard vulnerability, as well as the projected floodplain exposure considering future spatial patterns of floodplains under the 100-year, and 500-year storms, and subsequent changes in parcel-level average annualized losses (AAL). Our analysis of over 2,000 buyouts reveals that while buyout participants typically move to block groups with similar levels of social vulnerability, the destination locations generally are outside of current floodplains. However, under future floodplain projections, we identify emerging hotspots where high flood risk intersects with high social vulnerability and create high risks for properties. These findings underscore a critical gap in current buyout strategies: reliance on static floodplain maps risks reinforcing vulnerability under future storm patterns. Effective long-term risk management should be forward-looking to integrate future conditions and promote more managed relocation to prevent the shifting high-risk hotspots.

Author

• Meri Davlasheridze, Texas A&M University
  Presenting Author