Recently, the Union Ministry of Environment, Forests and Climate Change submitted an affidavit in the Supreme Court that the hydroelectric projects “aggravated the impact of floods” in Uttarakhand. While the ministry’s stance has been welcomed by environmentalists, it has delivered a blow to the Uttarakhand government and the companies building these projects as the State’s development agenda is linked to its capacity to generate hydroelectric power.
SC had ordered for the constitution of an expert body to assess the role of hydro electric projects in environmental degradation. Chopra Committee had submitted its report earlier this year. Sc proceedings further on will be based on this committee’s report. The report extensively analyses the impacts of hydro electric projects on the environment. I have summarized the major findings of the report. Though the report talks of mitigation strategies as well, my focus has been on the negative impacts of hydro electric projects. Some impacts might appear far fetched to you. But these are what we tend to ignore. If we are to analyse it holistically, the impact is much more beyond deforestation and landslides.
So, you know that rain and snow feed thousands of streams and rivers .Natural functions inherent to rivers include transporting water and sediments from their catchments to the sea; shaping the landscape and their own channels; supporting aquatic and terrestrial biota. These rivers also have enormous cultural and religious significance. Rivers provide livelihoods to local communities. Water is extracted from rivers for irrigation and domestic use. Livelihoods are also derived from adventure sports and tourism related to their cultural, recreational and aesthetic values. Glacier and snow melts provide good flows in the summer. This makes hydro- based areas generally power surplus in summer when power generation from rainfed rivers is minimal elsewhere. Power in excess of the state’s own needs is traded or banked with other states so that Himalayan states can buy power in the winter, when its own hydro generation is reduced.
The negative impacts of small hydro power projects can be less intense and therefore mitigated more easily. Large projects often lead to massive impacts that are hard to mitigate and may result in permanent scarring of nature and society. Many of them are not even seen or felt immediately. They emerge over time.
The major impacts are on the :
- geological environment
- river eco-system
- forests and terrestrial biodiversity
Let’s delve deeper into the impacts
♠ Impacts on Geological Environment
Firstly, the Himalayas are tectonically active zones. High tectonic activity can suddenly alter the contours of land and the course of rivers. The entire Himalayan ranges are prone to landslides and these areas where projects are going on are extremely vulnerable to landslides. Frequent movements along the ranges have loosened the local rocks making them vulnerable during the monsoon. Blasting has created problems in the form of ground vibrations. Road construction, quarrying and tunneling can trigger landslides.
Climate change will aggravate matters.Rapidly melting Himalayan glaciers will release large quantities of water into the rivers.
♠ Impacts on River Ecosystems
Disrupting River Flows: Hydro-power projects alter the natural flow patterns of rivers. Most of the hydro electric projects are diversion projects/ Run off the river projects which divert water upstream of a dam into a tunnel and drop it several kilometers downstream in order to obtain a large head. Storage projects generally reduce the annual discharge, the seasonal flow variability and the daily flow pattern downstream.
A river’s ecosystem develops in response to its water flow pattern. Species that need to remain under water all the time decrease. This change in the species populations and diversity can affect the entire aquatic food chain. Riverine vegetation, including that of the flood plains, changes as water and nutrients are withdrawn. Dams hold back sediments, leading to greater erosion of river beds and banks downstream.
Dry river beds: Once a river bed dries up or remains dry for significant periods, its ecosystem changes. It is believed that when large fractions of river lengths go dry due to multiple projects on them, changes in the micro climate may occur. The temperature in the river valley may increase. The accompanying reduction in moisture can diminish the valley’s biodiversity and productivity. Not something very obvious, innit?
Fragmentation of river length: When a number of dams are built in a series on a river, each dam fragments the river due to minimal flows between the dam and the power house. In these stretches the rivers lose their continuity and spread. As a result they are unable to perform their natural functions. Lack of connectivity limits the territory of species that migrate extensively along the length of the river. The isolated and localized populations become more vulnerable with increasing fragmentation. Again, this is not something you would think of in normal parlance.
Water Quality: By obstructing the natural flow of a river, a dam can cause significant changes in the physical, chemical and biological properties of river water. A flowing water ecosystem is characterized by high velocity, turbulence and mixing of water. Hydro electric projects cause stagnant water that has low velocity, low mixing and turbulence, limited aeration, sedimentation. These physical changes affect the water quality. Also, due to construction suspended solids cut off light at deeper levels , which affect the river ecology.
♠ Impacts on Forests & Terrestrial Biodiversity
Land is required for quarrying, construction of access roads etc. All this leads to deforestation. Quarrying leaves scars on mountain faces that take long to heal. More trees are damaged or destroyed when large boulders and debris roll down the mountain slopes during road construction. Air pollution from various operations and dust blown from the dumping grounds reduces photosynthesis activity of vegetation in the surrounding areas and hence decreases the bio-mass productivity. Such impacts can impair the terrestrial biodiversity value of river basins.
Animals and plant species that are dependent on riverine forests or ecosystems may disappear since they lose their natural habitats. Wild carnivores begin preying in surrounding villages, leading to increased human animal conflicts. Yes, could you have imagined, the dams on higher reaches are forcing the animals to plains? Riverine ecosystems are sensitive habitats which occur as ‘edge’ habitats between aquatic and upland ecosystems. Can you recall edge effect? They ensure continuous interaction between aquatic and terrestrial habitats through exchange of energy and nutrients. They are critical corridors for migration of several species.Riverine ecosystems facilitate river courses and help prevent soil erosion.
Hydro-power development adversely affects the productivity of agriculture by degrading or depleting a number of natural resources that constitute vital agricultural inputs. Perhaps the most obvious way hydro-power development restricts agricultural productivity is by reducing the supply of agricultural land. A loss of forest land, both as a direct and indirect is result of hydro-power development, which further constrains horticulture productivity.
Let’s put it all into perspective with the help of this table.
Conclusion
Hydroelectric Projects can cause several problems, even though
they burn no fuel. No doubt hydro-power projects have made an important contributions but such developments had significant impacts on local livelihood and the environment.It is essential that local issues are taken into consideration. World Commission on Dams recommends four values which should be taken into consideration before building a dam – equity, efficiency, participatory decision-making, sustainability and accountability. The non- governmental organizations should come forward to protect the environment and make the local people aware about their rights and the environment.
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