Human-Stream Corridor Interactions and Flood Resilience

Abstract

Flood damages in the United States continue to increase despite large investments to control stormwater. The rate at which flood damages are increasing significantly outpaces precipitation trends leaving societal trends largely to blame. Population growth and development within flood vulnerable areas such as floodplains and coastal regions is a large driver of the rising cost of floods. Not only does building in risky areas increase the likelihood of damage, but it also displaces and fragments natural habitats such as wetlands that provide flood attenuation as an ecosystem service. Efforts to mitigate flood damage have historically favored resistance based strategies. However the damages avoided through the use of flood control infrastructure (FCI) are often offset by their tendency to attract development into the stream corridor and increase downstream flood risk. The outcome of resistance based strategies to flooding, some have argued, has resulted in a loss of flood resilience. Despite such knowledge there have been no studies that have examined how these human-stream corridor interactions effect flood risk systematically. This study addresses this by using cross sectional regression models to isolate the influence of natural habitat modifications, FCI, and open space preservation on insured flood loss from 2006-2010 within the stream corridors of 273 developed watersheds along the Gulf of Mexico. Results indicate that stream hardening and the fragmentation of natural habitat significantly increase flood damage within the stream corridor, whereas efforts to preserve open space translate into significant savings in terms of damages avoided. These findings support the treatment of stream corridors as complex socio-ecological systems consisting of dynamic human-environment interactions. Instead of attempting to eliminate flood disturbances with costly resistance based infrastructure, cities should instead focus on flood resilience that leverages existing ecological systems and non-structural, avoidance based mitigation approaches to prevent flood damage.