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. Here the river completes its journey in India and enters Bangladesh in Dahagram, Rangpur Division. The river descends towards Barakhata, where there is Teesta Barrage of Bangladesh. Further it reaches Rangpur and Lalmonirhat town in Lalmonirhat District and Nilphamari District. After crossing Tepamadhupur Bazaar, Nagrakura Bazaar, Sundarganj and Bozra Bazaar, river Teesta joins Brahmaputra River at Haripur Port near Gaibandha, Phulchhari Upazila in Kurigram District of Bangladesh. Geography 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, tropical deciduous 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 enthusiasts. Between Rangpo town and the railway bridge (popularly called Lohapul or iron bridge) on it as it enters the plains at Sevoke, the Teesta flows with a very strong current, ideal for white river rafting. Towns like Teesta Bazaar and Melli have facilities for group rafting. Though the river looks innocuous, the underlying current is very strong. In 1915, G.P. Robertson, the then Municipal Engineer of Darjeeling, drowned after losing control of the boat in the turbulence while surveying the river. The boat struck a partially hidden boulder and was sucked in by a whirlpool, leaving no trace of the occupants. 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 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 India has an estimated total hydroelectric power potential of 84 GW at 60% load factor. Of this, Sikkim's potential share is