Gangotri Glacier is located in Uttarkashi District, Uttarakhand, India in a region bordering China. This glacier, one of the primary sources of the Ganges, is one of the largest in the Himalayas with an estimated volume of over 27 cubic kilometers. The glacier is about 30 kilometres (19 miles) long and 2 to 4 km (1 to 2 mi) wide. Around the glacier are the peaks of the Gangotri Group, including several peaks notable for extremely challenging climbing routes, such as Shivling, Thalay Sagar, Meru, and Bhagirathi III. It flows roughly northwest, originating in a cirque below Chaukhamba, the highest peak of the group.
The terminus of the Gangotri Glacier is said to resemble a cow’s mouth, and the place is called Gomukh or Gaumukh. Gomukh, which is about 19 km (11.8 mi) from the town of Gangotri, is the precise source of the Bhagirathi river, an important tributary of the Ganges. Gomukh is situated near the base of Shivling; in between lies the Tapovan meadow.
The Gangotri glacier is a traditional Hindu pilgrimage site. Devout Hindus consider bathing in the icy waters near Gangotri town to be a holy ritual, and many made the trek to Gomukh, with a few continuing on to Tapovan. One needs to trek from Gangotri till Gaumukh, passing Devgadh, Chirbhasa, Bhojwasa en route. Currently accommodation is available only at Bhojwasa, although forest check posts are present at both Chirbhasa and Bhowasa. The 2013 North Indian Floods destroyed much of this trail, and access is now a little difficult beyond Chirbhasa due to trail deterioration and a 2 km wide rockfall site.
NASA, in conjunction with Scientists from United States Geological Survey (USGS) and the National Snow and Ice Data Center (NSIDC), is developing a global inventory of all the world’s glaciers to help researchers track each glacier’s history. According to them, the Gangotri glacier, currently 30.2 km long and between 0.5 and 2.5 km wide, is one of the largest in the Himalayas. This glacier has been constantly receding since measurements began in 1780. Data for 61 years (1936–96) show that the total recession of Gangotri glacier is 1147 m, with the average rate of 19 m per year. However, over the last 25 years of the 20th century it has retreated more than 850 meters (34 meters per year), and 76 meters between 1996 and 1999 (25 meters per year).