Geohydrological disasters in the Himalaya are highly active and intense, and their frequency and magnitude are increasing. Major disasters include cloudburst- and glacier-burst–triggered debris flows, flash floods, landslides, and mass movements. Rugged and precipitous terrain, extreme meteorological events, high runoff, and human-induced activities further accentuate the intensity of these disasters. High volumes and velocities of debris and floodwaters, active tectonics, narrow valleys, and the high fragility of the landscape are the major drivers of these events. The construction of unplanned roads, large-scale hydropower projects, illegal mining along riverbanks, deforestation, and unplanned settlements in river valleys and on steep slopes accelerate the adverse impacts of geohydrological disasters. These incidents disrupt local economies and livelihoods and degrade the environment and forests. Early warning systems, nature-based solutions, risk management strategies, and community involvement in disaster risk reduction and preparedness can significantly mitigate the impacts of such disasters.

Dharali is a village and service centre, providing services (accommodation and food items) to the pilgrims/tourists and the population of rural areas, located on the left bank of the Bhagirathi River in Rajgarhi block of Uttarkashi district, along National Highway (NH) 108, which connects Haridwar city with the Gangotri highland pilgrimage. The Ksheer Ganga, also known as Kheer Gad, originates from the Shrikanth Glacier in the High Himalaya. It is a perennial stream that flows for nearly 10 km through steep slopes before joining the River Bhagirathi at the Dharali service centre. In its source region, there is a group of Saat Tals (seven lakes), all of which are glacier-fed. The Ksheer Ganga flows between elevations of 2,500 m and 6,000 m, with numerous perennial tributaries, all fed by glaciers. Land use within the catchment area varies from forests (including stony and grassland areas) to snow-covered regions, agricultural land, and built-up areas.

On August 9, 2025, at 1:50 PM, a massive debris flow struck the Dharali service centre. The debris volume exceeded 30 m in height and moved at high speed. Based on videos circulating on social media, the event lasted approximately 34 minutes—from the moment the debris entered the service centre until it was completely buried. The debris consisted of a mixture of large boulders, pebbles, gravels, and water. Approximately 13.4 ha of land, representing 8.12% of the total village area, was buried under debris. Rescue operations were severely hampered, as helicopter services were grounded due to adverse weather conditions. Continuous rainfall for more than two days had already raised the Bhagirathi River above danger levels, intensifying panic among survivors of the disaster. The average debris depth in the village now measures 10–15 feet. According to a report by the SDRF, nearly 1.4 million tonnes of debris have spread across 16 ha of land, transforming the Dharali service centre into a barren, stony desert.

The main drivers of the devastating debris flow in Dharali were multiple. However, some important drivers included the formation of landslide-dammed lakes, GLOFs, and a cloudburst event above 4,000 m on the upper slope of the Dharali service centre. This area is characterised by steep and precipitous slopes, a narrow valley, an extensive settlement area at the mouth of the Ksheer Ganga, and the presence of hotels and homestays located on the old river course and a debris fan. The area is highly fragile, consisting of loose earthen materials such as soil, gravel, pebbles, and boulders.

The debris flow was massive, and its velocity extremely high, causing it to split into two channels. One branch diverted into the old stream course, where dense settlements—including hotels, restaurants, and homestays—had been established. This violent stream completely washed away the settlements, while apple orchards were destroyed and swept into the Bhagirathi River. The second branch, flowing to the right, inundated additional settlements and deposited a vast volume of debris, forming an extensive debris fan. The volume and force of the flow were so great that it obliterated everything in its path, including reinforced cement embankment structures.

More than 56 hotels, restaurants, and homestays were buried under debris. The Kalp Kedar temple, believed to have been built by the Pandavas, was also completely submerged. Approximately 800 meters of road, including a bridge, was destroyed and buried beneath the debris. Dharali village has a population of 505 people. On the day of the calamity, a festival was being celebrated at the Sameshwar Dev temple, located on the opposite side of the Bhagirathi River. Many villagers from Dharali had gathered there, which inadvertently saved their lives. However, a considerable number of tourists and pilgrims were staying in the hotels and homestays within the village at the time. In addition, employees, labourers, and domestic animals were trapped and buried. Since records and registers of guests were also lost under the debris, the exact toll remains unknown. At Telgad, a debris flow of nearly 15 feet in depth buried an army base camp and the helipad. A total of 21 army personnel were swept away; of these, 10 were rescued, while 11 lost their lives and were buried under the debris. The debris flow also created an artificial lake on the Bhagirathi River, as the river’s flow was obstructed near Harshil.  

Natural hazards are a very common phenomenon in the Himalayan region and have been occurring since time immemorial. However, the conversion of these hazards into disasters is mainly due to anthropogenic activities. The Dharali calamity occurred largely because of the construction of settlements – houses and hotels – very close to the Ksheer Ganga. When a huge amount of debris flowed downstream, the entire settlement area was buried. Therefore, it is suggested that, in the future, during the rehabilitation process of Dharali village, landscape vulnerability should be carefully considered, particularly in terms of the proximity of settlements to streams and steep slopes. This should serve as an example for other rural and urban settlement areas. The entire region of the Upper Bhagirathi Valley has been declared an eco-sensitive zone; therefore, precautionary measures should be taken before undertaking any infrastructural development activities.