Dam frenzy fails to notice environmental concerns
M Rajshekhar, Economic Times, May 5, 2013
NEW DELHI: Housed in the ministry of environment and forests is a
quasi-independent body whose job it is to scrutinise every hydel project
for environmental damage. In its six years, the hydel environmental
assessment committee (EAC) has evaluated 262 hydropower plants and
irrigation projects, according to a February 2013 study by the South
Asia Network on Dams, Rivers and People (SANDRP), a Delhi-based anti-dam
organisation. It hasn't rejected a single one.
The prospect of a similar rate of clearance in Arunachal is alarming
researchers, who say projects are being cleared on a case-by-case basis,
without fully understanding the possible cumulative environmental
fallout of such a large build-up.
Take what will happen to the Lohit, which flows out of Arunachal and
into the Brahmaputra, when the Lower Demwe Hydro Electric Project on it
switches on. According to the project's environmental impact assessment
(EIA) report, the Lohit's flow is around 463 cubic metres per second
(cumecs) in winter, 832 cumecs in summer and 2,050 in the rains. (A
three cumecs flow is akin to a Tata Nano passing you every second.)
This will change once the dam comes up. For up to 20 hours a day, says
the report, the dam will trap the river, releasing just 35 cumecs of
water. The remaining will be released to spin the turbines only when
demand for electricity rises in the evening. At that time, the river's
flow will expand to 1,729 cumecs. As the reservoir empties out, the
river will again shrink to 35 cumecs.
This is palpably new. River flows ebb and rise over months. "But now,
what was an annual variation will now be a daily variation," says MD
Madhusudan, a biologist with Mysore-based Nature Conservation
Foundation. And this is from just one dam; each of the eight tributaries
emptying into the Brahmaputra has multiple dams coming up.
To gauge their combined impact, rifle through the EIA report for the
Jaypee Group's Lower Siang Project. If water from the three terminal
dams on the Lohit, Subansiri and the Siang rivers reaches the
floodplains at the same time, the Brahmaputra's height will fluctuate
daily by 2-3 metres as far as 65 km downstream. This unpredictability of
flow will affect fishing communities and those farming in the
There are other concerns. Multiple dams are coming up on each river.
Take the Lohit, where the distance between six dams is 1 km, 9.5 km, 1.8
km, 3.8 km and 1.8 km, respectively. There are no authoritative studies
on what such clustering portends for a river or how they will behave
during a quake.
This part of the country is rocked by one earthquake over 8 on the
Richter scale once every 100 years or so. "The largest quake in this
area was 8.7. Now, there will be a series of cascading dams, each with a
small reservoir, on each river," says Chandan Mahanta, a professor
teaching environmental engineering and engineering geology at IIT
Guwahati. "These are things people have not seen. We need more simulation."
"The issues surrounding these dams are very different from those
relating to dams in the plains," adds Dulal Goswami, a former member of
the hydel EAC. "There, the main issues are relocation, rehabilitation
and inundation. Here, the issues are seismicity, landslides and
flashfloods. " In a paper published in Science magazine this January, R
Edward Grumbine, a professor at China's Kunming Institute of Botany, and
Maharaj K Pandit, a professor at Delhi University's Centre for
Interdisciplinary Studies of Mountain and Hill Environment, estimate
that India is planning to build 292 dams across the Himalayas.
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