Context: Recently, Subansiri Lower Dam project on the Assam-Arunachal border (at Gerukamukh in Assam’s Dhemaji district) was hit by a landslide during pre-monsoon rain in the region.
The Subansiri river
- The Subansiri river has its origin in Tibet and it is an antecedent river.
- It enters India near the town of Taksing (Arunachal Pradesh) and flows east and southeast through Miri Hills, then south to the Assam Valley at Dulangmukh in Dhemaji district, where it joins the Brahmaputra River at Jamurighat in Lakhimpur district.
- Small tributaries of the Subansiri include Rangandi, Dikrong and Kamala.
- The Subansiri lends its name to two districts in Arunachal Pradesh: Upper Subansiri and Lower Subansiri.
- The high topographic variation makes this river a potential zone for harnessing it for hydropower. The districts situated on the bank of the Subansiri River are flood prone during monsoon season.
- The Subansiri River is the largest tributary of Brahmaputra River.
The Brahmaputra river
- The Brahmaputra has its origin in the Chemayungdung glacier of the Kailash range near the Mansarovar Lake. From here, it traverses eastward longitudinally in a dry and flat region of southern Tibet, where it is known as the Tsangpo.
- The Rango Tsangpo is the major right-bank tributary of this river in Tibet. It emerges as a turbulent and dynamic river after carving out a deep gorge in the Central Himalayas near Namcha Barwa.
- The river emerges from the foothills under the name of Siang or Dihang.
- It enters India west of Sadiya town in Arunachal Pradesh. Flowing southwest, it receives its main left bank tributaries, viz., Dibang or Sikang and Lohit; thereafter, it is known as the Brahmaputra.
- The Brahmaputra receives numerous tributaries in its long journey through the Assam valley. Its major left bank tributaries are the Burhi Dihing and Dhansari whereas the important right bank tributaries are the Subansiri, Kameng, Manas and Sankosh.
- The Brahmaputra enters Bangladesh near Dhubri and flows southward.
- In Bangladesh, the Tista joins it on its right bank from where the river is known as the Jamuna. It finally merges with the river Padma, which falls in the Bay of Bengal. The Brahmaputra is well-known for floods, channel shifting and bank erosion.