From Places to People: Human-centric Characterization of Life Activity Flood Exposure for Intra- and Inter-city Analysis

Abstract

A human-centric perspective on flood exposure assessment of flood-hazard vulnerability transcends the conventional focus on spatial exposure by quantifying the effect of daily human activities in flood-prone areas. Using a novel index to quantify the time individuals spend in flood-prone areas, this method characterizes latent flood exposure. Calculations rely on millions of fine-resolution location-based data points collected anonymously from smartphones of opted-in users. A comparative analysis of multiple U.S. metropolitan cities based on latent flood exposure with similar extents of spatial flood risk reveals significant spatial disparities in LAFE. A bimodal distribution in life activity flood exposure index values in 18 coastal metropolitan areas reveals flood exposure disparities. The inter-city analysis results also uncovers the role of urban forms and structures in shaping LAFE, revealing how spatial clustering of flood hazards and distance-decay characteristic of human visitation can exacerbate flood exposure. Our findings provide a novel and more human-centric approach to characterizing and quantifying flood exposure by shifting focus from places to people. The life activity flood exposure captures the extent to which a population’s daily life activities would be disrupted due to flooding and could capture the socio-economic aspects of flood exposure (such as loss of access to critical facilities and work) more objectively than the existing approaches. The findings provide interdisciplinary researchers and practitioners across urban sciences, flood risk management, emergency response with novel human-centric measure and insights to better examine flood exposure and risk.