ABSTRACT
This study investigates the September 26 to 28, 2024, extreme rainfall in Central Nepal and its role in triggering widespread slope failures. Twenty-five meteorological stations across Nepal recorded unprecedented 24-hour totals, some exceeding return periods of over 5,000 years. The event followed a saturated monsoon season, with cumulative rainfall of 1,880 mm, the second highest in last 24 years. Field surveys documented shallow landslides, debris flows, and embankment failures along major infrastructure corridors such as the BP Highway and Kanti Lokpath, mainly on saturated cut and fill slopes. Long-term rainfall variability from 2000 to 2024 within and around the Kathmandu Valley was also analyzed to provide historical context. Findings highlight the limitations of current slope design under extreme rainfall and recommend integrating rainfall statistics into slope engineering, strengthening early warning systems, and developing a centralized rainfall–landslide database.
