Fourth Khangri Glacier expedition achieves key breakthroughs in Arunachal

The fourth Khangri Glacier scientific expedition has achieved major scientific milestones, including the first-ever reconnaissance of the high-risk Dharkha Tso glacial lake and the discovery of aquatic life at a depth of 20 metres in Rani Lake, in Arunachal Pradesh’s Tawang district.

The week-long expedition, conducted from November 8 to 14, is a joint flagship initiative of the Centre for Earth Sciences and Himalayan Studies (CESHS) here, and the National Centre for Polar and Ocean Research (NCPOR) under the Union Ministry of Earth Sciences.

CESHS Director Tana Tage said the mission aims to deepen scientific understanding of glacier dynamics, climate change impacts and water resource sustainability in the Eastern Himalayas.

Since its launch in 2023, the expedition series has focused on long-term glacier monitoring to build robust datasets critical for cryospheric and hydrological research.

Led by senior glaciologist Dr Parmanand Sharma and coordinated by Nyelam Sunil, the 2025 team comprised 11 scientists and engineers from CESHS, NCPOR Goa, Nagaland University and North East Regional Institute of Science and Technology (NERIST) near here.

Despite heavy snowfall preventing access to the glacier for summer mass balance measurements, the team successfully carried out high-resolution aerial surveys of the Khangri Glacier and the Rani Lake using advanced drone platforms equipped with precision sensors, Tage said.

A significant breakthrough came from an unmanned sonar-based bathymetric survey of Rani Lake, which revealed aquatic life at 20 metres, an important finding in a high-altitude glacial environment, he said.

Researchers also retrieved critical summer-season data from the automatic weather station (AWS) and automatic water level recorder (AWRL) installed earlier on the glacier. Additionally, they completed 24-hour stream discharge assessments downstream of Khangri Glacier to analyse meltwater behaviour and hydrological variations.

A landmark achievement of this year’s expedition was the first scientific scaling and reconnaissance of Dharkha Tso, one of the 29 GLOF-susceptible lakes identified by NDMA in Arunachal Pradesh.

Dharkha Tso, located at 16,145 ft in Mirathang Valley, has no direct access route and required an arduous ascent of 3.8 km.

The team trekked through more than 3 feet of snow across a 700-metre stretch, navigating low oxygen levels, steep ridges, slippery trails and hazardous gorges. Despite the conditions, the scientists reached the lake and completed aerial drone mapping along with water and sediment sampling for detailed GLOF hazard assessment, Tage added.

CESHS said the successful completion of the fourth expedition marks a significant step forward in India’s scientific efforts to study glacier health, meltwater contribution, hydrometeorological patterns and glacial lake outburst flood (GLOF) risks in the Eastern Himalayas.