Modeling the Dynamics of Extreme Natural Hazard Habitation for Improved Disaster Project Analysis

Most extreme natural hazard mitigation projects are analyzed using monetary indices, thereby not fully accounting for social benefits. Rigorous modeling and quantification of nonmonetary social impacts are needed to effectively estimate project benefits. In the case of habitation this requires modeling the infrastructure systems that provide critical products and services. This study proposes and demonstrates a system dynamics-based model to quantify the habitation-related impacts of mitigation projects by simulating the availability of habitable residential units based on the performance of critical internal infrastructure systems (CIIS). The model was applied to the Halls Bayou watershed in Houston, Texas, under various storm scenarios, with and without a planned mitigation project. Simulation results show that, in the case study, wastewater treatment outages primarily drive initial habitation loss, while residential shelter availability governs recovery duration and habitation loss scale. In a 500-year storm scenario, the mitigation project decreased total habitation loss scale by 100,320 residence-days (18%) and shortened recovery duration by 14 days (9%). The model structure helps explain these results. This dynamic modeling approach and model offer a new tool for disaster planning and management by facilitating the incorporation of social impacts into mitigation project analyses.