Sun Kosi

The Sunkoshi, also spelt Sunkosi, is a river of Nepal that is part of the Koshi or Saptkoshi River system in Nepal. Sunkoshi has two source streams, one that arises within Nepal in Choukati, and the other more significant stream that flows in from Nyalam County in the Tibet region of China. (See especially Figure 1). The latter is called Bhote Koshi in Nepal and Matsang Tsangpo in Tibet. Due to the significant flows from Bhote Koshi, the Sun Koshi river basin is often regarded as a trans-border river basin.

River course

The Sunkoshi's headwaters are located in the Zhangzangbo Glacier in Tibet.Mool, P. K.; Joshi, S. P.; Bajracharya, S. R. (2001). Glacial Lake Outburst Floods and Damage in the Country. Pages 121–136 in: Inventory of Glaciers, Glacial Lakes and Glacial Lake Outburst Floods: Monitoring and Early Warning Systems in the Hindu Kush-Himalayan Region, Nepal. International Centre for Integrated Mountain Development, Kathmandu. Both Sunkoshi and Bhotekoshi river courses together form one basin that covers an area of about .

The Indravati meets the Sunkoshi at Dolaghat, up to where it is followed by the Arniko Rajmarg. From there, the Sunkoshi flows eastwards through the valley formed between the Mahabharat Range and the Himalayas. Tamakosi, Likhu, Dudhkosi, Arun and Tamor are its left tributaries and Indravati is the right tributary.

The average annual flow is 2.2 x 10¹⁰ m³. The average sediment load is 5.4 x 10⁷ m³.

The Tamur and the Arun rivers join the Sunkoshi at Tribenighat to form the Saptkoshi, which flows through the Chatra Gorge across the Mahabharat Range on to the Gangetic plain.Sharma, U. P. (1996). Ecology of the Koshi river in Nepal-India (north Bihar): a typical river ecosystem. In: Jha, P. K., Ghimire, G. P. S., Karmacharya, S. B., Baral, S. R., Lacoul, P. (eds.) Environment and biodiversity in the context of South Asia. Proceedings of the Regional Conference on Environment and Biodiversity, 7–9 March 1994, Kathmandu. Ecological Society, Kathmandu. Pp 92–99.
There are few more smaller tributaries of the Sunkoshi such as Rosi Khola, Junga Khola, and Sapsu Khola.

Names and etymology

ne, सुनकोशी

In Nepali language, the word "sun" means gold and golden; and the word "kosi" means river.

Koshi River system

The Koshi River drains eastern Nepal. It is also known as Saptkoshi River because of the seven rivers joining in east-central Nepal to form this river. The main rivers forming the Koshi River system are Sunkoshi, Indravati, Tamba Koshi, Bhote Koshi, Dudh Kosi, Arun and Tamur Rivers. The Saptkoshi River flows through the Chatra Gorge in a southerly direction into northern Bihar and joins the Ganges.

The Sunkoshi contributes about 44% of the total water of the Saptakoshi, the Arun 37% and the Tamur 19%.

Infrastructures

*Sunkosi–Kamala multipurpose project: The Sunkoshi has a 90% reliable flow of . It was proposed to divert the water from a small weir across the river near Kurule through a tunnel and a 61.4 MW associated power house to the Kamala River, flowing through central Nepal. Some of water would be transferred to the Kamala River for the purposes of irrigation and further generation of power.

Hazards

In July 1981, a sudden ice avalanche caused a Glacial Lake Outburst Flood in the moraine-dammed Zhangzangbu-Cho Lake in the headwaters of the Poiqu in Tibet. The ensuing debris flow destroyed bridges, and sections of both the Arniko and the Nepal–China highways.

On 2 August 2014, a landslide at Jure blocked the river downstream from Barabise and created a large lake that submerged a hydropower station. This huge rockslide of approximately blocked the Sunkoshi River upstream of Jure village. This landslide killed approximately 155 people, destroyed approximately 120 houses completely and 37 partially. The area has been declared a flood crisis zone, and local communities are evacuated. Power supply was interrupted, and the Arniko Highway blocked.

Water sports

The Sunkoshi is used for both rafting and intermediate kayaking. It has grade III-IV rapids. The most common put in point of a Sunkoshi river trip is Dolaghat, at an elevation of and it ends at the Chatra Gorge at , a distance of around .

The first successful descent of the Sunkoshi was made in late September 1970 by Daniel C. Taylor, Terry Bech, Cheri Bremer-Kamp, and Carl Schiffler. They entered the river at Dolaghat and exited at the Nepal-India border. Their expedition took four days. Prior to this successful trip, there are four known unsuccessful attempts to descend the river, and one unsuccessful attempt to ascend the river in a jet boat under the leadership of Edmund Hillary.Taylor, D. C. "Yeti: An Ecology of a Mystery." New Delhi: Oxford University Press, pp. 119-130.

Notes

References

External links

Sun Kosi River
OpenStreetMap, retrieved 19 December 2021.

Bhote Kosi River
(Upper Sun Kosi), OpenStreetMap, retrieved 19 December 2021.

Arun River
OpenStreetMap, retrieved 19 December 2021.

Sapta Kosi River
OpenStreetMap, retrieved 19 December 2021.

{{Kosi basin

Rivers of the Province No. 1
Rivers of Tibet
International rivers of Asia