The Teesta River originates fromTeesta Khangtse Glacier, west ofPahunri (or Teesta Kangse) glacier above 5,400 m (17,700 ft), and flows southward through gorges and rapids in theSikkim Himalaya.[3]
After this point, Teesta River changes its course southwards flowing into West Bengal and some more tributaries likeRelli River, Riyang River, Geil Khola etc joins. Than the river hits the plains atSevoke, 22 km (14 mi) northeast ofSiliguri, where it is spanned by theCoronation Bridge andSevoke Railway Bridge linking the northeast states to the rest ofIndia. After crossing Sevoke, the river is fed by some small tributaries like Chel Khola, Neora Khola, Leesh Khola etc, and then reachesGajoldoba where there is Teesta Barrage. The river then flows throughJalpaiguri, where Jalpaiguri Teesta Bridge links Northeastern States. The river flows further down throughMekhliganj andHaldibari inCooch Behar district, where it is spanned byJoyee Setu, the longest roadway bridge of West Bengal with length 3.8 kilometres.
Through its course, the Teesta River has carved outravines andgorges in Sikkim meandering through the hills with thehill 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 forrafting.
During themonsoon, 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.[6][7]
James Rennell's 1776 map shows an earlier flow of the Teesta meeting theGanges in three channels before a devastating flood in 1787 changed its course
In the past, the Teesta flowed south from Jalpaiguri in three channels: thePunarbhaba,Atrai andKaratoya Rivers. The Teesta changed course as a result of the flooding of 1787, turning southeast to become part of theBrahmaputra.[8]
Hydel project on the Dikchu, a tributary of Teesta
The Teesta Barrage is a major irrigation project in Bangladesh, inLalmonirhat District. Construction started 1979 and was completed in 1997–98.[9]
India has an estimated total hydroelectric power potential of 84 GW at 60% load factor. Of this, Sikkim's potential share is 2.9%, or about 4.29 GW.[10]
The successfully completed major projects and dams of Teesta River System are as follows:
Dikchu River Hydroelectric Power Project: Output: 96 MW on Dikchu River, tributary of River Teesta, Location -Dikchu,Gangtok district,Sikkim. Constructed by- Sneha Kinetic Power Projects Pvt. Ltd.[23][24]
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.[26][27][28]
Negotiations have been going on since 1983.[29][30][31] In 1983, a temporary arrangement was reached: Bangladesh would receive 36%, India 39% while, and the remainder would remain unallocated.[30] Both countries signed a water sharing treaty in 1996 which would look into water sharing between the two countries in general following theGanges water dispute.[30] The water sharing remains a challenge.[30]
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.[32]
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.[10]
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.[3][33][34]
^abcMullick, 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.doi:10.1002/ird.597.
^abMeetei, L. I.; Pattanayak, S. K.; Bhaskar, A.; Pandit, M. K.; Tandon, S. K. (2007). "Climatic imprints in Quaternary valley fill deposits of the middle Teesta valley, Sikkim Himalaya".Quaternary International.159 (1):32–46.Bibcode:2007QuInt.159...32M.doi:10.1016/j.quaint.2006.08.018.
^Chaudhuri, Samita; Chaudhuri, Utpal (2015).And the Teesta Flows... Niyogi Books. p. 188.ISBN978-93-83098-70-5.
^"Teesta-V D01535".India Water Resources Information System. National Remote Sensing Centre. Government of India. Archived fromthe original on 18 October 2014. Retrieved15 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.
Mesbah-us-Saleheen (2012),"Tista River", in Sirajul Islam and Ahmed A. Jamal (ed.),Banglapedia: National Encyclopedia of Bangladesh (Second ed.),Asiatic Society of Bangladesh
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