The Himalayan region is facing an unprecedented threat from rapidly expanding glacial lakes, with Uttarakhand emerging as one of the most vulnerable states to catastrophic Glacial Lake Outburst Floods (GLOFs). A groundbreaking scientific study has raised serious concerns about Bhilangana Lake, whose dramatic expansion could trigger devastating floods affecting thousands of people and critical infrastructure.
From Non-Existent to Exponential Growth
Researchers have uncovered the alarming transformation of Bhilangana Lake through detailed analysis spanning decades. The lake did not exist in 1968, beginning its formation around 1980 with relatively slow growth until the turn of the century. However, the situation changed dramatically after 2001.
After 2001, the expansion became exponential, stated Pawan Patidar, senior research fellow at Wadia Institute of Himalayan Geology and lead author of the study. The research attributes this rapid growth to accelerated glacier thinning and retreat, with the parent glacier losing 0.7 km² of area since the mid-1990s and experiencing thinning rates of up to 0.7 metres per year.
Devastating Flood Scenarios Revealed
The study employed sophisticated hydrodynamic simulations to model worst-case scenarios, presenting disturbing results that should concern every downstream community. A sudden moraine-dam breach could discharge up to 3,645 cubic metres of water per second, with flow velocities exceeding 30 m/s in upper reaches.
The floodwave would inundate 6.8 km² of valley floor, reaching the first settlement of Deokhri within just 1.2 hours. Residents of Deokhri could experience water depths of 11 metres, while communities at Ghuttu and Ghansali, along with the Bhilangana hydropower stations, could face flood depths above 8-10 metres.
The study specifically highlighted the vulnerability of roads, bridges and power infrastructure directly in the inundation path, raising concerns about both human safety and economic stability in the region.
Climate Change Driving the Crisis
Rising temperatures have been identified as the primary driver behind the lake's rapid expansion. The data reveals an annual warming trend of 0.028°C per year in mean temperature, with maximum and minimum temperatures rising even faster at 0.052°C and 0.050°C per year respectively.
Warming is most pronounced between July and August, the prime melt months, with the zero-degree isotherm climbing higher to reach above 6,400-7,300 metres in summer. Climate projections suggest even more alarming scenarios, with temperatures potentially rising by 8-11°C by 2100 in the region.
The study also mapped multiple over-deepened zones in the basin that may evolve into future lakes, further increasing long-term hazard potential for the Himalayan region.
Urgent Call for Action
Researchers emphasize the critical need for immediate measures to address the growing threat. The study calls for early-warning systems, continuous monitoring and detailed hazard assessments, particularly crucial given that the Bhilangana valley hosts several hydropower projects essential to Uttarakhand's energy supply.
The research, published in the journal 'Hydrological Processes,' was conducted by a collaborative team from Wadia Institute of Himalayan Geology, National Geophysical Research Institute Hyderabad, Jawaharlal Nehru University, IIT Madras, National Institute of Hydrology Roorkee and other institutions, funded by the central government's department of science and technology.
As climate change continues to reshape the Himalayan landscape, the study serves as a stark warning about the urgent need to protect vulnerable communities and infrastructure from the growing threat of glacial lake outburst floods.
