The Teesta River originates from Teesta Khangtse Glacier, west of Pahunri (or Teesta Kangse) glacier above 5,400m (17,700ft), and flows southward through gorges and rapids in the Sikkim Himalaya.
After this point, Teesta River changes its course southwards flowing into West Bengal and some more tributaries like Relli River, Riyang River, Geil Khola etc joins. Than the river hits the plains at Sevoke, 22km (14mi) northeast of Siliguri, where it is spanned by the Coronation Bridge and Sevoke Railway Bridge linking the northeast states to the rest of India. After crossing Sevoke, the river is fed by some small tributaries like Chel Khola, Neora Khola, Leesh Khola etc, and then reaches Gajoldoba where there is Teesta Barrage. The river then flows through Jalpaiguri, where Jalpaiguri Teesta Bridge links Northeastern States. The river flows further down through Mekhliganj and Haldibari in Cooch Behar district, where it is spanned by Joyee Setu, the longest roadway bridge of West Bengal with length 3.8 kilometres.
Through its course, the Teesta River has carved out ravines and gorges in Sikkim meandering through the hills with the hill station of Kalimpong lying just off the river and the city of Siliguri at the foothills of Himalaya. Variegated vegetation can be seen along this route. At lower elevations, tropicaldeciduous trees and shrubs cover the surrounding hills; alpine vegetation is seen at the upper altitudes. The river is flanked by white sand which is used by the construction industry in the region. Large boulders in and around the waters make it ideal for rafting.
During the monsoon, Teesta River distends its banks, both in size and turbulence. Landslides in this region often dam up parts of the river in this season. It has also caused severe flooding, multiple times during monsoon in Bangladesh.
Changes in course of rivers
James Rennell's 1776 map shows an earlier flow of the Teesta meeting the Ganges in three channels before a devastating flood in 1787 changed its course.
In the past, the Teesta flowed south from Jalpaiguri in three channels: the Punarbhaba, Atrai and Karatoya Rivers. The Teesta changed course as a result of the flooding of 1787, turning southeast to become part of the Brahmaputra.
Hydroelectric projects and barrages
Hydel project on the Dikchu, a tributary of Teesta
The Teesta Barrage is a major irrigation project in Bangladesh, in Lalmonirhat District. Construction started 1979 and was completed in 1997–98.
India has an estimated total hydroelectric power potential of 84GW at 60% load factor. Of this, Sikkim's potential share is 2.9%, or about 4.29GW.
The successfully completed major projects and dams of Teesta River System are as follows:
Teesta III Dam: Output - 1200MW Dam Location - Chungthang, Mangan district, Sikkim. Powerhouse Location - Singhik, Mangan district, Sikkim. Constructed by - Teesta Urja Limited. On 4 October 2023, heavy rains caused a glacial lake outburst flood. The flood reached the Teesta III Dam at midnight, before its gates could be opened, destroying the dam in minutes.
Gati Hydropower Project: A 110MW Gati Hydropower Project lies on River Rangpo, a tributary of River Teesta. Location - Between the town of Rorathang and Rongli of Pakyong District in Sikkim Constructed by - Gati Hydropower Limited.
Dikchu River Hydroelectric Power Project: Output: 96MW on Dikchu River, tributary of River Teesta, Location - Dikchu, Gangtok district, Sikkim. Constructed by- Sneha Kinetic Power Projects Pvt. Ltd.
Madhya Bharat Power Corporation Limited: on Ranikhola, a tributary of Teesta, Output: 96MW Dam location- Ranipool, Gangtok district, Sikkim. Powerhouse Location- Kumrek, Pakyong district, Sikkim.
The other three completed projects are significantly smaller and minor—Lower Lagyap, Upper Rongni Chhu and Mayang Chhu projects.
Water sharing challenge
Disputes over the appropriate allocation and development of the water resources of the river have remained a subject of conflict between India and Bangladesh for almost 35 years, with several bilateral agreements and rounds of talks failing to produce results.
Negotiations have been going on since 1983. In 1983, a temporary arrangement was reached: Bangladesh would receive 36%, India 39% while, and the remainder would remain unallocated. Both countries signed a water sharing treaty in 1996 which would look into water sharing between the two countries in general following the Ganges water dispute. The water sharing remains a challenge.
In recent developments, Bangladesh's interim government water advisor, Syeda Rizwana Hasan, told news agency PTI (Press Trust of India) on September 1, 2024, that both upper and lower riparian countries must follow international water-sharing principles. If a treaty remains out of reach, it could mark a significant shift in India-Bangladesh relations if diplomacy fails.
Seismic concerns
Teesta River area is in the seismically active Zone-V and has experienced micro-seismic activity. According to India's Ministry of Environment & Forests, the Teesta River dam projects have been approved with the requirement that they adopt suitable seismic coefficient in the design for the dam, tunnel, surge shaft and power house. The projects are cascaded over the length of the river, do not store large amounts water, have small reservoirs, and therefore the projects are expected to have very low risk from the reservoir induced seismicity in the area.
Climate and tectonics
The Teesta River has preserved good imprints of climatic and tectonics along its valleys and catchments. The interrelationship between climate, erosion, deposition and tectonic activities is not properly understood to date. These are being studied.
123Mullick, M. R. A.; Babel, M. S. & Perret, S. R. (2011). "Discharge-based economic valuation of irrigation water: Evidence from the Teesta River, Bangladesh". Irrigation and Drainage. 60 (4): 481−492. Bibcode:2011IrrDr..60..481M. doi:10.1002/ird.597.
↑"Teesta-V D01535". India Water Resources Information System. National Remote Sensing Centre. Government of India. Archived from the original on 18 October 2014. Retrieved 15 June 2014.
↑Mukul, Malay (2000). "The geometry and kinematics of the Main Boundary Thrust and related neotectonics in the Darjiling Himalayan fold-and-thrust belt, West Bengal, India". Journal of Structural Geology. 22 (9): 1261–1283. Bibcode:2000JSG....22.1261M. doi:10.1016/S0191-8141(00)00032-8.
↑Mukul, Malay; Jaiswal, M.; Singhvi, A. K. (November 2007). "Timing of recent out-of-sequence active deformation in the frontal Himalayan wedge: Insights from the Darjiling sub-Himalaya, India". Geology. 35 (11). The Geological Society of America: 999–1002. Bibcode:2007Geo....35..999M. doi:10.1130/G23869A.1.
External links
Wikimedia Commons has media related to Teesta River.
Mesbah-us-Saleheen (2012), "Tista River", in Sirajul Islam and Ahmed A. Jamal (ed.), Banglapedia: National Encyclopedia of Bangladesh (Seconded.), Asiatic Society of Bangladesh