Brahamaputra Basin

Brahamaputra Basin
Figure 2. Monthly average temperature (1969-2004)
1.3.3 Trends and variability
Trends have been generated based on area weighted average and regression analysis techniques.
Figure 2 shows the variability of annual average rainfall of Brahmaputra basin over the last 34 years
(1971-2004). The general rainfall trend in the basin shows that rainfall pattern in the basin
decreasing. But the changing trend is not drastic. In 1974, the Brahmaputra upper sub basin
experiences maximum 4947.54 mm rainfall which is followed by 4051.94 mm rainfall in 1985. The
Brahmaputra upper sub basin accounts least rainfall of 1776.57 mm in the year 1989. The maximum
fall in the temperature observed in the Brahmaputra lower sub basin with 1720.65 mm in the year
1992.
Figure 3. Trend of annual average rainfall (1971-2004)
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