Teesta - Ministry of Power

5.2.3 Temperature And Humidity
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Preliminary Feasibility Report
Teesta (I) HE Project (4 x 80 MW)
The climate in the region is fairly humid and moist. The abrupt variation in altitude is
chiefly responsible for abrupt changes in the climatic conditions and aided by the
complex orography, the area experiences frequent rainfall of varying intensity and
duration. The maximum and minimum temperature varies from 39 0 C in summer to 6 0
C in winter and the relative humidity varies from 80% to 100%. Temperature and
relative humidity observations are being made in the basin at Dikchu site where
Teesta-V H.E project is being constructed by NHPC and at TLDP-III and TLDP-IV
sites, as a part of cascade development on Teesta river. The monthly maximum,
minimum temperatutre and relative humidity at Dikchu from Jan 1998 to Dec 2001 is
enclosed as Annexure-5.1 and annual maximum and minimum temperature from
1998 to 2001 is given in Table 5.1.
Month
& Year
Table 5.1
Temperature And Humidity Data At Dikchu
Maximum
Temp o C
Minimum
Temp o C
Max. Relative
Humidity %
Min. Relative
Humidity %
1998 38.0 7.0 99.0 89.0
1999 39.0 6.0 99.0 90.0
2000 39.0 7.0 97.0 85.0
2001 31.0 11.0 97.0 90.0
Overall 39.0 6.0 99.0 85.0
5.2.4 Precipitation Characterstics
In the Teesta basin the southwest monsoon normally sets in the third week of May and
withdraws in the second week of October. The major portion of the catchment being
hilly and the river flowing in steep gradient, heavy rains in the upper and middle
catchments has an immediate effect of rendering the plains to flash floods.