River Bhagirathi, one of the biggest tributaries of Ganga, originates from Trans-Himalayan region of Nelang-Jadhong-Pulumsumdu (Jahnavi-Jadganga sub-watershed) and Greater-Himalayan regions of Gangotri-Gaumukh (upper most Bhagirathi sub-watershed), Jalandhrigad (originating from 19650 ft high peak of Lamkhaga and 17330 ft high pass of same name on Himanchal border), Pilangad (originating from Shahastratal situated at 15300 ft) and Khatling glacier area (upper most Bhilangana sub-watershed). The Trans-Himalayan region of Nelang-Jadhong-Pulumsumdu, the home of the endangered Bhotia tribe called JAD, is bordered by high pass of Thagla (19127 ft), Tsang Chokla (19345 ft), Mulingla (18600 ft) and Sarup Choti (20040 ft) on the north by Greater Himalayan peaks on Mana (22298) ft), Srikailas (22742 ft), Matri (22060 ft) and Kalidhang (19640 ft) on the south. Glaciers of Srikailas, Surji Bamak, Nilapani and Lambigad are located in this region. It comprises of Trans-Himalayan tributaries of Bhagirathi River called Jadhandgad, Jahnavigad, Jadganga and Managad. The Gangotri-Gaumukh region of Greater Himalayan (inner Trans-Himalaya) is located on the south of Trans-Himalyan region and on its eastern & southern boundary are located the high Himalayan peaks of Satopanth (23420 ft), Chaukhamba (23190 ft), Kharchakund (21695 ft), Jogin (21200 ft) Jaunli (21760 ft), Gangotri-group (21680 ft) and Rudugaira (19090 ft). Glaciers called Chaurangi, Gangotri, Ratavan, Kirti, Bhrigupant and Kedarganga etc are located in this area. The famous Hindu temple of holly Gangotri, along with snout of Gangotri glacier called Gaumukh and Tapasthali of Raja Bhagirath, i.e. Bhagritath-Shila & Tapasthali of Parvati, i.e. Gaurikund also situate there. Jahnavi is supposed to be the river where the Ashram of Saint Jahnu was located, who imponded Ganga in his Kamandal as the Pauranic scriptures say. Jalandharigad joins Bhagirathi at Harsi. Glaciers of Karanpani and Ratna Bamak are located in its catchment on the south of which is located 19270 ft high pass of Dumdharkhandi. Pilangad joins Bhagirathi at village Malla and its catchment is situated between 18754 ft high peak of Dropadi-Ka-Danda on the north and 13300 ft high Bugyal of Kyarki & 12523 ft high Bugyal of Kushkalyan on the south. The biggest tributary of Bhagirathi called Bhilangana having its confluence at the dam site of Tehri, originates from Khatling glacier. Khatling area is situated exactly south of the Gangotri-Gaumukh region and west of valley of Kedarnth and is surrounded by 21760 ft high peak of Jaunli on the west and Chauki-patangriyan Dhar range on the reast besides the peaks of Kedarkanta, Bhartekanta, Sphatikling, Jogin and Gangotri group on the north.
The geographical area of the region is approximately 4.7 lakh ha which is much more than half of the total area of the basin (62%). All the glaciers and peaks covered by perennial snow are situated in this region. Greater Himalayan region receive heavy snow fall during winter and rainfall during summer. As such this area is susceptible to avalanches and land-slides. But the Trans-Himalayan area receives much less snow or rainfall and as such is dry and arid. In both the areas grow bushes or grass only, that too in patches. The region is very thinly populated but immigrating herdsmen use this region for extensive grazing and pilgrims visit shrines like Gangotri in large number during summer. Since 1960s the area became vulnerable to foreign aggression and for national defence needs security forces had to be deployed in the region all the year-round. This has increased fuel requirement, especially during winter resulting in greater pressure on the forest for firewood. The project of Maneribhali Stage-1 is commissioned and Stage-2 is in progress in this region. Few projects such as Lanka, Bhatwari etc have been approved recently.
