GUWAHATI, June 16 � Even as the Union Government mulls over a response to Chinese plans to divert or dam the Brahmaputra, some experts are raising concerns over a range of issues, which include a depletion of ground water in the entire valley of the river.
It is feared that if the Brahmaputra is diverted or further dammed in its course in Tibet, both the lean and peak season flow will be affected in the downstream, which would cascade into depletion of the ground water reserves in the valley that spreads over Assam.
A senior geologist in the Gauhati University, who preferred not to be named, said, "Any major diversion of the Brahmaputra in Tibet will have definite consequences for Assam, its ground water supply and thus on scores of people who depend on it. Ground water replenishment would be adversely affected if the base level of the river is to go down," he said.
For a largely agricultural State like Assam, the lowering of ground water would bring ruin to scores of agricultural communities who rely on wells, tube wells or bore wells.
The geologist, who is well acquainted with the geologic formation of the Brahmaputra Valley, said that every summer the aquifers in its valley are recharged by the river. In winters, aquifers release water which flow into the Brahmaputra.
The ground water utilization in Assam at present is less than 20 per cent, but as population increases and ground water diminishes a new set of problems is likely to arise.
Moreover, decrease in flow, he reasoned, would result in reduction in flushing efficiency and increase in more sediment deposition in the riverbed. More siltation and loss of cropland can be expected in such circumstances.
Significantly, he added that diversion of the Brahmaputra, or more dams in its upper courses reducing the volume of water will be a challenge to several hydro power projects planned on the Siang (precursor of the Brahmaputra) and its tributaries in Arunachal Predesh.
"Yes, power projects will have a problem as the peak and mean flow of the river starts to recede. At Pasighat the lean season flow is around 2,000 Cusec, while the peak season flow is around 20,000 Cusec. It is already a big range," he noted.
According to him, the State Government or Union Government must take some steps to understand the prevailing situation. He recommended the use of digital data loggers at Pasighat, Dibrugarh, Tezpur, Guwahati and Jogighopa to extract vital information about the river's flow.
Another need is to measure the bed form morphology of the Brahmaputra using high resolution satellite data from satellites like Cartosat 1 covering both the lean and the peak season periods.