Unit 3.7 – Impact of DAMS on Environment and People
Environmental
Impacts of Dams
The environmental consequences of large
dams are numerous and varied, and includes direct impacts to the biological,
chemical and physical properties of rivers and riparian (or
"stream-side") environments.
1. The
dam wall itself blocks fish migrations, which in some cases and with some
species completely separate spawning habitats from rearing habitats.
2. The
dam also traps sediments, which are critical for maintaining physical processes
and habitats downstream of the dam (include the maintenance of productive deltas,
barrier islands, fertile floodplains and coastal wetlands).
3. Another
significant and obvious impact is the transformation upstream of the dam from a
free-flowing river ecosystem to an artificial slack-water reservoir habitat.
Changes in temperature, chemical composition, dissolved oxygen levels and the
physical properties of a reservoir are often not suitable to the aquatic plants
and animals that evolved with a given river system. Indeed, reservoirs often
host non-native and invasive species (e.g. snails, algae, predatory fish) that
further undermine the river's natural communities of plants and animals.
4. The
alteration of a river's flow and sediment transport downstream of a dam often
causes the greatest sustained environmental impacts. Life in and around a river
evolves and is conditioned on the timing and quantities of river flow. Disrupted and altered water flows can be as
severe as completely de-watering river reaches and the life they contain. Yet even subtle changes in the quantity and
timing of water flows impact aquatic and riparian life, which can unravel the
ecological web of a river system.
5. A
dam also holds back sediments that would naturally replenish downstream
ecosystems. When a river is deprived of its sediment load, it seeks to recapture
it by eroding the downstream river bed and banks (which can undermine bridges
and other riverbank structures, as well as riverside woodlands). Riverbeds
downstream of dams are typically eroded by several meters within the decade of
first closing a dam; the damage can extend for tens or even hundreds of
kilometers below a dam.
6. Riverbed
deepening (or "incising") will also lower groundwater tables along a
river, lowering the water table accessible to plant roots (and to human
communities drawing water from wells) .
Altering the riverbed also reduces habitat for fish that spawn in river
bottoms, and for invertebrates.
In aggregate, dammed rivers have also
impacted processes in the broader biosphere.
Most reservoirs, especially those in the tropics, are significant
contributors to greenhouse gas emissions (a recent study pegged global
greenhouse gas emissions from reservoirs on par with that of the aviation
industry, about 4% of human-caused GHG emissions).
Recent studies on the Congo River have
demonstrated that the sediment and nutrient flow from the Congo drives
biological processes far into the Atlantic Ocean, including serving as a carbon
sink for atmospheric greenhouse gases.
Large dams have led to the extinction of
many fish and other aquatic species, the disappearance of birds in floodplains,
huge losses of forest, wetland and farmland, erosion of coastal deltas, and
many other severe environmental impacts.
(source: https://www.internationalrivers.org/)
Human
Impacts of Dams
Large dams have forced some 40-80
million people from their lands in the past six decades, according to the World
Commission on Dams. Indigenous, tribal, and peasant communities have been
particularly hard hit. These legions of dam refugees have, in the great
majority of cases, been economically, culturally and psychologically
devastated.
Those displaced by reservoirs are only
the most visible victims of large dams. Millions more have lost land and homes
to the canals, irrigation schemes, roads, power lines and industrial
developments that accompany dams. Many more have lost access to clean water,
food sources and other natural resources in the dammed area. Millions have
suffered from the diseases that dams and large irrigation projects in the
tropics bring. And those living downstream of dams have suffered from the
hydrological changes dams bring to rivers and ecosystems; an estimated 400-800
million people--roughly 10% of humanity--fall into this category of
dam-affected people.
In response to the massive human rights
problems and environmental impacts of large dams, affected people and
supporting local and international organizations have joined together to fight
for change in how and whether dams are planned, designed and built. This
movement includes thousands of environmental, human rights, and social activist
groups around the world. International dam-affected people’s meetings in
Brazil, Thailand and Mexico in recent years have brought together dam-affected
peoples and their allies to network and strategize, and call for better
planning of water- and energy-supply projects. And every year, groups from
around the world show their solidarity with those dispossessed by dams on the
International Day of Action for Rivers, a global event to raise awareness about
the impacts of dams and the values of free-flowing rivers.
(source: https://www.internationalrivers.org/)
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The
8 Mega Dams of North East States of India
The sister states of North East India are considered as the
future powerhouse of India. North east India is a slice of paradise, untouched
and yet to explore, Due to the abundantly of natural resources and deep river valley’s these are considered
as one of the best suited projects for
mega dams. Some of the big dams of
north east Indian states are list as follows.
Ranganadi
Dam-Arunachal Pradesh
The Ranganadi Dam is Concrete gravity dam build on the Ranganadi
River, located in the Yazali Arunachal Pradesh. Ranganadi Dam was the first
mega dam built in Arunachal Pradesh with an height of 68 m and serves as run of
the river hydroelectric generation scheme and no water storage. Subansiri Lower
Dam is an under construction gravity dam on the Subansiri River and Dibang Dam
is planned concrete gravity dam in the state.
Doyang
Dam-Nagaland
The Doyang Dam is build across the Doyang river near the Wokha
village in Nagaland, Its a rockfill dam with a height of 92m. The big dam is
visible from most of the hill tops of area and have become the best place for
water sports in the state. Doyang Reservoir is user for power generation,
fisheries and also provide shelter to flora and fauna around.
Khuga
dam-Manipur
The multipurpose Khuga dam is one of the seven river valley
irrigation projects completed on Imphal River with the famous
Loktak Lake for power supply to Manipur and other sister
states. Khuga dam height is a 38m tall structure located towards the
south of Churachandpur town. Tipaimukh Dam is the major dam project, proposed
with height of 162m across river Barak in Manipur.
Tuirial
Dam-Mizoram
The Tuirial Dam is an earth fill and gravity dam with 74m height
across the Tuirial river near Kolasibin the Indian state of Mizoram. The zoned
earth fill dam is situated at the 74m above from the deepest level of river bed
and generate 60MW power with its turbines. Kolasib is a small town around the
dam with tribal population,who follow its cultures and traditions. Serlui B Dam
is another earth fill and gravity dam on Serlui river with height of 51m in the
state of Mizoram.
Gumti
Dam-Tripura
The Gumti dam is build across the gumti river in near Dumbur in
the state of Tripura with a 30-metre height to generate 8.6 MW power. Gumti dam
forms a large lake called Gumti reservoir, the reservoir attracts a large
number of resident and migratory water birds, also the Gumti Wildlife Sanctuary
is home to many wild animals such as Indian bison,Barking dear and Elephants.
Umiam
Dam-Meghalaya
The Umiam Dam is constructed acorss the Umiam river stream near
to capital Shillong with an height of 27.5 m. Umiam Dam project was the first
Dam build in the North-east region of India. The reservoir is called Umiam
Lake, its a famous tourist spot in the state and one of the most popular
destination for adventures water sport. The Artificial Lake is also used for
irrigation, fisheries and drinking water for to local.
Subansiri
dam-Assam
The Subansiri dam also known as Subansiri Lower Dam, is a under
construction gravity dam across the Subansiri River at the border of Assam and
Arunachal Pradesh. Subansiri dam is the most controversial dam project in among
the proposed dams of North east region of India. Subansiri dam will be a run of
the river power project with an height of 116m. The pagladia dam is proposed
multipurpose mega dam to be built across the river Pagladiya near Thalkuchi
village Assam.
Rangit
Dam-Sikkim
The Rangit Dam of sikkim is a 45 m tall concrete gravity dam
build across on the Ranjit River to generate power of 29 MW. Rangit Dam is
situated near to Gangtok and build over the confluence of two rivers Rathong
Chu and Rangit Rivers. The river valley reservoir of Rangit Dam is one of the
most popular venue for fishing boating and other recreational water sports. Teesta-V
Dam is another concrete gravity
dam which is 95 m height on the Teesta River at Dikchu, Sikkim.
(source:http://www.walkthroughindia.com/walkthroughs/the-8-mega-dams-of-north-east-states-of-india/)
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PROBLEMS WITH DAMS :
A Case study of India's Tipaimukh High Dam. Article written by Dr. R.K. Ranjan Singh
Communities Say No to India's Tipaimukh High Dam
By: Dr. R.K. Ranjan Singh
Date: Friday, September 18, 2009
The proposed Tipaimukh High Dam would dam the Barak River 500 meters downstream from the confluence of its tributary the Tuivai River in Manipur State. More than half of the 900-kilometre-long Barak falls within India; its lower half drains Bangladesh. The Barak system is the second largest drainage system in Northeast India. The entire riverine ecosystem of the Barak River Basin supports an endemic agrarian civilization thriving on biodiversity-based agro-ecological systems that have profound local and global significance.
The 163-meter-high Tipaimukh Dam will permanently submerge more than 275 sq km of land. The project is expected to have firm power generation of 412 MW. Almost none of its power will be sent to the state where the dam will be built.
There is no complete study that focuses on geo-tectonic problems or biodiversity and environment, health, socio-economic and hydrological impacts of the project. The absence of meaningful consultation with the indigenous peoples contradicts the keystone strategic priority developed by the World Commission on Dams, that no dam should be built without the demonstrable acceptance of the affected people, and without the free, prior, informed consent.
History of Resistance
Communities from Manipur have resisted Tipaimukh High Dam for more than 15 years. Resistance began because the people of Manipur had seen the devastating impact of Loktak Hydroelectric Project. This project has been the single biggest reason why local people question the new project. Any person who is aware of Loktak will tell you how it has submerged large tracts of agricultural lands; ousted large number of farmers from their livelihood without compensation, thus reducing self-sufficiency in rice production, and devastated a fragile wetland ecosystem. This has further made Manipur more economically dependent on mainland India, which is just the opposite of the promises made when the project was conceived. The people of Manipur are now fully aware that Manipur gets little electricity from the project.
The struggle against Tipaimukh is not restricted to Manipur state, but is also in Bangladesh too, where the immediate impact of the dam will be felt. The dam could also impact watersheds and ecosystems in northern Burma.
In addition, we are now waking up to the fact that two other dams in the area, Mapithel and Khuga dams, also deceived the people with promises that have not yielded any result. Now we see how wrong decisions made in the past can create havoc for our future.
Tipaimukh was not conceived and designed for the people of Manipur, or for that matter for the people of India's northeast region. It was initially designed to control floods in lower Assam, and then to generate electricity for the Indian state-owned utility NEEPCO for sale outside the region. For all these years the dam builders have not informed or consulted the people, especially those who will be directly impacted. The dam is not based on local requirements, but is imposed from above, to serve unknown economic interests. An issue of consent is a must when they want to bring in a project of such magnitude that will submerge villages, fertile agricultural land, forests, and not even meet local needs. Local organizations have also proposed alternatives, including smaller, less destructive dams.
Flawed Resettlement Plan
If constructed, the dam will have negative impacts on 9,126 sq km in the state of Manipur alone. A large number of indigenous communities, mostly belonging to the Zeliangrong and Hmar peoples, will be permanently displaced and deprived of their livelihood. One should be aware that these affected areas are almost half of the present size of Manipur. A small state like Manipur cannot afford to bargain away an area of this size for a tiny bit of electricity. We must look for alternative source of energy where it has least impact on land. We have already had 60,000 hectares of agricultural land submerged due to Ithai Dam alone. For our food security we cannot afford to lose any more land.
If one looks closely at the project's proposed resettlement and rehabilitation plan, it is clear that they have not taken into account intergenerational concerns. For example, rice fields cannot be compensated at today's market price only, as it is done by NEEPCO. For we all know that a plot of land has benefited both the generation in the past and will serve our future and cannot be assessed for the present market value only. Such shortsighted compensation will only create impoverishment and hardship for those displaced. A more important issue is the close link of indigenous peoples to their land, water, forest and their culture. Any sizeable loss of land is loss of the community itself.
As known elsewhere, dams have created or accentuated ethnic conflict. Here, too, there are already divisions along ethnic lines that can have longterm implications for all peoples. In an already fractured place such as this, it is imperative that the state does not allow projects that widen the ethnic divide. In addition, conflict with other states and also with Bangladesh as a result of the dam cannot be ruled out and will need to be addressed before agreeing to the project.
We are also aware that the construction of large dams brings in laborers from outside the region. We are witness to that the fact that outsiders have come to work for Loktak hydro project and other dams, and that these workers have stayed after the work is done, putting pressure on local communities and natural resources. A massive project like Tipaimukh will bring in more than 30,000 workers from outside and it is certain that these outsiders will cause issues for local people.
The site selected for Tipaimukh project is one of the most seismically active in the entire world, recording at least two major earthquakes of 8+ on the Richter scale during the past 50 years. The proposed dam site falls on an active fault line. Several large earthquakes have been recorded near the Tipaimukh site.
The people who have fought the dam have used all democratic means possible to seek the government of India to stop the dam. Memorandums and letters by the score, rallies, sit-in protests, blockades, strikes, press releases, meetings, leaflets, and email campaigns have all been used. Five public hearings conducted by the government have been boycotted. But these all went into the dustbin of the government. One wonders what it would take for the government to listen to the people, and stop the dam. We must insist that Tipaimukh is not an answer to the energy crisis that we presently face. If the government is sincere enough to solve this crisis then it must right away say no to this destructive project, and initiate a people-inclusive dialogue on energy.
Original Source: https://www.internationalrivers.org/resources/communities-say-no-to-india-s-tipaimukh-high-dam-1762
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