Record Rainfall Triggers Devastating Flash Floods in Nepal

Starting on September 28, Nepal experienced the most intense rainfall in over half a century, leading to catastrophic flash floods and landslides in the Kathmandu Valley and nearby districts. The country received 20% of its annual rainfall over two days. On the back of the recent monsoon season, soil was already saturated and thus unable to absorb this extreme precipitation. Meteorologists from Nepal’s Department of Hydrology and Meteorology (DHM) confirmed record-breaking rainfall across multiple stations in the capital, marking the highest levels recorded in 54 years. The floods have caused significant damage to infrastructure, with at least 322 homes and 16 bridges destroyed across Nepal. 

The disaster has claimed at least 236 lives thus far, with many more missing, and caused landslides and riverine floods across more than 50 districts. Local branches of the Red Cross, along with government and multilateral agencies, are working together on rescue and relief operations. The Nepal Red Cross Society activated an early action protocol on September 30 to assist nearly 5,500 vulnerable residents by providing evacuation support, hygiene kits, and health awareness campaigns

The exceptionally intense rainfall was made more extreme by a low-pressure system in the Bay of Bengal, combined with the unusually northern position of the monsoon trough. The low-pressure system in the Bay of Bengal and a northward-shifted monsoon highlights how climate change is affecting weather patterns. Warmer air, caused by global warming, holds more moisture, leading to more intense rainfall during monsoons.  

The Himalayas, similar to the polar regions and the rest of the cryosphere, are warming faster than the planetary average. As part of this rapid warming, the thawing of local permafrost is destabilizing surrounding mountains, making the soil significantly more vulnerable to erosion and weather impacts, such as the recent extreme rains. These effects may be stronger this year due to the historic snow “drought” experienced throughout much of the Hindu Kush Himalaya during the 2023-2024 winter. Many communities in Nepal, including Kathmandu, are built in the valleys of glaciers, enabling people to capitalize on snow and glacial runoff for irrigation, food security and other economic needs; making the communities even more vulnerable to flooding events. 

This extreme weather event aligns with the Intergovernmental Panel on Climate Change’s (IPCC) predictions that Nepal will experience more intense rainfall as a result of climate change. It underscores the urgent need for international efforts in accelerating the phase out of fossil fuels and the need for international funding to help vulnerable countries adapt to these evolving climate challenges.

Featured image: Precipitation over Kathmandu, Nepal on 28th September 2024, Ventusky

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