Recent flash floods and mudslides in Uttarkashi district, Uttarakhand, caused four fatalities and damage to buildings and infrastructure. The event occurred despite the absence of a cloudburst, a common trigger in the region. Continuous heavy rainfall combined with the district’s rugged topography led to the disaster. About the geographical and climatic factors is essential to grasp the causes and risks of such events in Uttarkashi.
Geographical Features of Uttarkashi
Uttarkashi lies in the upper Himalayas with elevations from 800 to 6,900 metres above sea level. It contains glaciers and perennial rivers including the sources of the Ganga and Yamuna near Gangotri and Yamunotri. The terrain is sharply undulating with high ridges, narrow valleys, and deep gorges. The land slopes steeply towards the southwest, sometimes dropping by 800 metres in valleys. This rugged landscape influences water flow and sediment movement.
Rainfall Patterns and Climate
The district receives an average annual rainfall of 1,289 mm, mostly during the southwest monsoon from June to September. July is the wettest month with about 312 mm of rain. Monsoon currents penetrate valleys deeply due to the southern Himalayan slope. Thunderstorms are common in the hills. Historical data shows rainfall can vary widely, with 1969 recording 2,436 mm, nearly double the average.
Causes of Flash Floods and Mudslides
Heavy rainfall over several days saturated the soil and glaciers, increasing vulnerability. The topography with loose moraine and minimal vegetation allows rain and melting snow to trigger landslides and debris flows. These materials rush into rivers, gaining force and causing flash floods downstream. Layers of ancient mudslides also make the land unstable, so even moderate rainfall or minor earthquakes can cause disasters.
Definition and Absence of Cloudburst
A cloudburst is defined by the India Meteorological Department as rainfall exceeding 100 mm in one hour over a 10 km by 10 km area. On the day of the incident, Uttarkashi recorded only 2.7 mm in 24 hours by 8:30 am and no hourly rainfall met the cloudburst threshold. Thus, the flash floods were caused by prolonged rainfall and terrain factors, not by a cloudburst.
Impact of Climate Change
Rising temperatures have accelerated glacier melting and increased rainfall intensity in the Himalayas. This adds stress to the already fragile landscape of Uttarkashi. Continuous rain and rapid deglaciation destabilise slopes and increase the frequency of landslides and floods. Climate change thus magnifies natural hazards in the region.
Challenges in Disaster Management
The steep and inaccessible terrain complicates rescue and relief operations. Limited vegetation and loose soil reduce natural barriers against landslides. Monitoring rainfall and glacier changes is critical but difficult due to terrain and weather variability. Building resilient infrastructure and early warning systems remain priorities for reducing future risks.
Questions for UPSC:
- Critically discuss the impact of Himalayan topography on natural disasters such as landslides and flash floods.
- Examine the role of climate change in altering monsoon patterns and its effects on the Himalayan ecosystem.
- Analyse the challenges faced in disaster management in mountainous regions and suggest sustainable mitigation strategies.
- Estimate the socio-economic consequences of recurrent flash floods in Uttarakhand and how they influence regional development policies.
