Lingza - Ministry of Power

35
Preliminary Feasibility Report
Lingza HE Project (3 x 40 MW)
The river Teesta is one of the main Himalayan Rivers, which originates in the glaciers of
Sikkim at an elevation of over 8500m above mean sea level. It is being snow fed by the
glaciers Zemu, Changame Khanpu, Talung etc. It is an international river, which flows
through the states of Sikkim and West Bengal in Indian Territory and then to Bangladesh.
The river rises in mountainous terrain and is formed mainly by the union of two hill
streams Lachen Chu and Lachung Chu at Chunthang in North Sikkim. The river upto this
reach generally flows in a very steep gradient and the slope of the Teesta river upto the
confluence of Lachen chu and Lachung chu is about 1 in 20. After the confluence of
Lachen chu and Lachung chu at Chungthang the river gradually increases in width and
takes a wide loop flowing down to Singhik dropping in elevation from EL 1550 m to EL
750 m. It is here after traversing about 20 Km that the river confluences with Tolung
Chu.
The area has a rugged terrain with the surrounding peaks reaching a maximum elevation
of approximately 4000m. The nallah joins Teesta river almost perpendicularly. The
terrain hosts a rich growth of vegetation. In general the river flows in southeasterly
direction. Numerous valleys are seen in the area, which are occupied by cultivated
terraces. Few high level terraces have been observed in this area especially in vicinity of
Lingza and Kayem village.
5.2.1 Cascade Development In Teesta Basin
The river Teesta has tremendous potential for development of hydro power, as the river
descends from an elevation of about 3600m to about 300m over a distance of about 175
Km. According to the preliminary reconnaissance survey by Central water and power
Commission in 1974, the river could be harnessed under a cascade development for
hydro power generation. The cascade development proposed at that stage consisted of
power generation in six stages on river Teesta. Out of these schemes, NHPC had
submitted a DPR for Teesta H.E project, Stage-III in 1990. The diversion structure for
Teesta-III was proposed to be constructed at Chungthang, which lies downstream of the