How a hydropower project threatens the wildlife of Arunachal Pradesh
- October 29, 2023
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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How a hydropower project threatens the wildlife of Arunachal Pradesh
Subject : Geography
Section: Physical geo
Context:
- In 2012, 1,750-megawatt Lower Demwe hydroelectric project in Arunachal Pradesh received wildlife clearance.
Lower Demwe hydroelectric project:
- Location: Lohit district, Arunachal Pradesh, India.
- The dam is proposed in an eco-sensitive zone on the Lohit river, 50 metres from the Kamlang Wildlife Sanctuary.
- It will directly impact the Ganges river dolphin, critically endangered bird species, the Bengal florican, and the white-bellied heron, Assam roofed turtle, tigers, elephants and also impact Parshuram Kund, a Hindu pilgrimage site.
- The white-bellied heron is known to be extremely vulnerable to the loss and degradation of its preferred habitat (free-flowing natural river courses), and hydroelectric projects are causing direct mortality of birds through power lines.
- The project will submerge a 4-km stretch of the Lang river, a left-bank tributary of the Lohit river.
- The established protocol is to conduct assessments before construction and seek mitigation of adverse impacts only as a last resort.
Dams: Doing major harm but a manageable problem?
- Dam construction is one of the oldest, most preferred tools to manage freshwater for various uses. The practice reached a peak internationally in the 1960s and ’70s, but in recent years dam construction has faced increasing global criticism as the hefty environmental price paid for their benefits piles up.
- Damming the rivers is the largest single anthropogenic alteration of the freshwater cycle.
- There are close to 60,000 large dams & 16 million small dams, storing about a sixth of the globe’s total annual river flow to the oceans.
- The flows of most major waterways have been impacted by dams globally. Only 37% of rivers longer than 1,000 km (620 mi) remain free-flowing, and just 23% flow uninterrupted to the sea. Natural flows will be altered for 93% of river volume worldwide by 2030, if all planned and ongoing hydropower construction goes ahead.
- This global fragmentation of rivers has led to severe impacts. Dams have contributed to an 84% average decline in freshwater wildlife population sizes since 1970. More than a quarter of Earth’s land-to-ocean sediment flux is trapped behind dams. Dams also impact Earth’s climate in complex ways via modification of the carbon cycle.
- But dams are needed for energy, agriculture and drinking water, and are an inevitable part of our future.
- Impact of dams: decline of freshwater species, dams block the migration of fish and other aquatic species, separating them from breeding grounds and reducing population sizes, Migratory fish populations have fallen by 76% since 1970, decline in fishery activities, downstream water temperatures change, natural ebb and flow of the hydrological cycle is altered, reduced flow of phosphorous, nitrogen and silicon trapped behind dams, impact on deltas (Mekong Delta in Vietnam, the world’s third-largest delta).
- Species threatened by dam construction are: Migratory fishes like- sturgeon, salmon, hilsa and gilded catfish, Amazon’s giant catfish, Irrawaddy dolphins, beluga sturgeon, Mekong giant catfish, the Chinese paddlefish (already extinct).
Dams, deforestation and climate change:
- Cheap, government-subsidized hydropower attracts energy-intensive, ecologically destructive industries, such as bauxite mining and aluminum smelting and industrial gold mining.
- Tropical hydroelectric plants and their reservoirs can emit two to three times more greenhouse gasses than natural gas, oil, or coal plants, due to deforestation and potent methane emissions.
Penobscot River Restoration Project:
- This effort to revive New England’s second-largest river system entailed the removal of two dams and construction of a stream-like bypass channel around a third.
Kruger National Park:
- Formed in 1911 in South Africa, it is one of the largest protected areas in Africa.
- Issues faced by the park: Overgrazing, veld degradation and erosion, Siltation behind the dams due to catchment basins and stagnant waters that are nurturing cyanobacteria and poisoning the animals that drank the water.