Typhoon rainfall can trigger urban waterlogging within hours, but hydrodynamic modelling is impractical for rapid screening. For Typhoon Haikui (2311) across Guangdong, Guangxi, and Hainan, we integrated half-hourly Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) Final Run V07 precipitation, LandScan population exposure (E), and an impervious-surface factor (I) derived from the China Land Cover Dataset into a Typhoon Rainfall Risk Index (TRRI). Rainfall hazard (H) combines event-total rainfall, rainfall duration, and maximum 3 h rainfall. Hazard clustered along the Guangdong coast, where maximum event-total and 24 h rainfall reached 529.7 and 272.8 mm, respectively. TRRI high-risk zones occupied 12.45% of the three-province land area. Defined by the largest weighted component, H-, E-, and I-dominated cells accounted for 60.5%, 33.4%, and 6.1% of the high-risk class. Of 22 reported waterlogging locations in the event-focused domain, 19 fell in high-risk zones; the 86.36% hit rate versus a 26.09% background area yielded an enrichment ratio of 3.31 (p < 0.001). In a descriptive full-domain check, all 49 distinct locations were medium or high. Relative to  alone, TRRI reclassified 20.59% of land upward and 20.64% downward, while 58.77% remained unchanged. TRRI supports rapid event-scale screening and risk prioritization for targeted disaster-prevention decision-making.
 

urban waterlogging; typhoon rainfall; rapid assessment; population exposure; impervious surface; TRRI; Typhoon Haikui