Public Warning and Outreach to Reduce Pre-Evacuation Delay in Mountain Flash Flooding: Evidence from Liulimiao Town in Beijing

Abstract

Flash floods compress decision time, making warning quality and outreach central to timely evacuation. Building on the revised Protective Action Decision Model (PADM), we distinguish two sources of delay: information frictions in warnings (clarity, credibility, actionability, and verification burden) and action frictions tied to preparedness, capability, and constraints. We then model evacuation initiation with a discrete-time event-history approach. We analyze a post-disaster survey of 197 households in Liulimiao Town, Beijing, following the late-July 2025 “25·7” flash-flood event. Departures are front-loaded, with 42.6% occurring within 15 minutes, yet 20.8% extend beyond 120 minutes. Latent class analysis identifies three friction profiles with distinct departure trajectories. Model-based standardization indicates that improving warning actionability and strengthening household mobilization readiness, defined by preparedness, route knowledge, and self-efficacy, especially in combination, are associated with earlier departures and substantially lower tail-delay risk.