ABSTRACT
In September 2024, Nepal experienced an unprecedented flood event that severely damaged the Banepa–Bardibas (BP Highway, NH13), a critical east–west corridor running along the Roshi and Sunkoshi River. This paper presents a diagnostic assessment of the event based on field survey, drone imagery, and hydro-meteorological analysis. Damages were classified into geotechnical, hydraulic, and structural failures, linked to a 773-year year extreme rainfall, slope saturation, sediment-laden flows, and design vulnerabilities. The study identifies how traditional design standards and reactive maintenance approaches fall short under intensifying climate extremes. Key lessons include the need for climate-adjusted design thresholds, alignment planning based on river morphology, sediment-informed hydraulic design, and proactive monitoring. These insights inform broader strategies for enhancing the resilience of river-corridor highways in mountainous regions. The BP Highway serves as a critical case for embedding climate logic into national infrastructure planning.
