Himalayan Nallahs emerging as silent killers in monsoon disasters: SANPRP

By A Representative 

When Jahlma Nallah starts roaring, “we cannot sleep,” said 80-year-old Devi Singhji of Himachal Pradesh last October. His fears came true this monsoon, as the Himalayan rivulet once again flooded catastrophically, blocking the Chenab and adding to the devastation across the region.

The 2025 monsoon has been relentless in Jammu and Kashmir, Himachal Pradesh, and Uttarakhand. According to the Himachal Pradesh State Disaster Management Agency, at least 310 people have died in rain-related incidents this season. Ten more perished during the Manimahesh Yatra in Chamba, while over 100 lives were lost in Jammu and Kashmir during the Chasoti and Vaishno Devi pilgrimages. Landslides in Ramban in April and August claimed additional victims. In Uttarakhand, the Dharali, Yamuna, and Char Dham Yatra disasters together left more than 100 dead. With the India Meteorological Department warning of further heavy rainfall in September, the situation remains dire.

While rainfall, river flooding, and landslides dominate the headlines, rivulets locally called nallahs have played a critical but less understood role in intensifying the destruction. These glacier-fed streams—such as Pagal Nallah, Jahlma Nallah, and Karpat Nallah in Himachal, Chasoti Nallah in Jammu, and Kheerganga Rivulet in Uttarakhand—turn into ferocious torrents during the monsoon, carrying debris, boulders, and even avalanche waters downstream. Their proximity to human settlements makes them uniquely dangerous. “Several nallahs in the Himalayas are called ‘Pagal’ (mad one) or even ‘Khooni’ (killer) for a reason,” the South Asia Network on Dams, Rivers and People (SANPRP) noted.

Encroachments and unplanned construction have further narrowed and redirected their natural courses, especially in towns like Bhuntar, Shimla, Kullu, and Mandi. The situation is particularly hazardous at muhanas—the confluences of nallahs and rivers—where fertile land has attracted settlements and farms. Flashfloods here deposit massive debris, as seen in Dharali, Chasoti, Lippa, and Pagal Nallah. Such debris-laden nallahs, when merging with major rivers, can even trigger landslides and bank failures on the opposite shore.

The advocacy group has called for urgent measures. “It is unthinkable that after repeated tragedies, there are no rain gauges, flood gauges, or alarm systems for these sites,” said Parineeta Dandekar of SANPRP, who prepared the note based on field visits, interviews, and scientific studies. Climate scientist Dr. Roxy Matthew Koll of the Indian Institute of Tropical Meteorology stressed the need for “a dense automatic rain-gauge network with telemetry, river-water-level sensors, cameras, and community sirens at hot spots.”

Longer-term strategies must also include lowering water levels of dangerous glacial lakes, strict zoning along nallah banks, site-specific studies, and independent assessments before major infrastructure is approved. Local knowledge is equally vital. MLA Anuradha Rana from Lahaul and Spiti told SANPRP that while “Pagla Nalla in Darcha floods after rain, Jahlma Nalla in Lindur floods after intense sun and heat”—showing the varied triggers behind these disasters.

Communities, too, have been raising alarms for years. “Farmers, teachers, pastoralists, and women have a wealth of information about their landscape and the way it is changing. These insights need to form the foundation of any adaptation mechanism,” the SANPRP note emphasized.

As the Himalayas face repeated monsoon tragedies, the group warns that identifying and managing vulnerable nallahs must be treated as an urgent priority—before more lives are lost.