A New Approach to Household Flood Resilience Assessment using the Recovery-Damage Ratio (RDR) Index

Flood resilience is the ability of a system to withstand and efficiently recover from flood damage. Although resilience has become central to disaster research, most household-level flood assessments remain focused on estimating immediate damage, offering limited understanding of post-flood recovery dynamics. To address this gap, this study develops a new approach that extends conventional flood damage assessment toward resilience, capturing variations in household recovery trajectories across different resilience properties. The novelty of this research lies in the formulation of a new index that quantifies the dynamic nature of post-flood recovery relative to the damage incurred. We achieve this by coupling empirical flood damage curves with a time-dependent Recovery–Damage Ratio (RDR) index, creating the flood resilience curve. As a proof of concept, we utilized survey data from Marikina City, Philippines, and set the longitudinal information of income, post-flood financial aid, and house type as surrogate indicators of the four properties of resilience, namely robustness, redundancy, rapidity, and resources. This analysis reveals disparities in recovery speed associated with income class and external assistance. This also uncovers a paradox that while structural robustness dictates initial damage, low-flood depth households may delay repairs, whereas highly inundated households rapidly mobilize reconstruction. Furthermore, the comparison of paired flood events shows a shift in household resilience after experiencing severe flooding, consistent with localized flood adaptation and preemptive actions. Ultimately, this approach offers a reproducible framework to quantify post-flood recovery through the lens of interdependent resilience properties.