In recent news, a 27-year-old hermit from Haridwar, Swami Atmabodhanand, has ended his 194-day fast. The protest was against the imminent environmental impact of sand mining and the construction of dams on vital rivers contributing to the Ganga. This article will elaborate on the various environmental effects associated with damming rivers, highlighting why the Swami’s stance holds significant importance.
The Negative Implication of Dams on Habitats
One of the major issues with dams is habitat fragmentation. Unless specifically designed for fish migration, dams serve as barriers obstructing the migratory patterns of fish species. This not only affects the fish populations but also impacts other species within the food chain that either feed on or are preyed upon by these fish.
Destruction Through Flooding
Dammed rivers contribute to flooding and destruction of surrounding habitats due to the created reservoir upstream from the dam. The overflowing reservoir inundates surrounding ecosystems, displacing or even killing numerous organisms including plants, wildlife, and at times, humans.
A Key Contributor to Global Climate Change: Greenhouse Gases
Dams play a significant role in contributing to global climate change through their indirect production of greenhouse gases. The upstream flooding kills plant life, causing it to decompose and release large amounts of carbon into the atmosphere. Furthermore, the water stagnation in the dam reservoir leads to oxygen depletion, paving the way for methane production, which is a potent greenhouse gas.
Disturbance of Natural River Flow: Sediment Build-Up and Erosion
The natural flow of a river is interrupted when a dam is built, causing sediment to pile up behind the dam. This results in new riverbanks, river deltas, alluvial fans, braided rivers, oxbow lakes, levees, and coastal shores. These changes can lead to drastic shifts in the biodiversity of plant and animal life. Additionally, downstream erosion intensifies due to a lack in sediment flow.
Drastic Impact on Local Fish Populations
Local fish species often fail to adapt to the new environment following dam construction, leading to local population extinction. Factors affecting survival include blockage of migration routes, disconnection from flood plains, changes in the river’s flow, temperature alterations, turbidity, and dissolved oxygen levels. Organic materials accumulate behind dams, causing oxygen depletion and in some cases, triggering algae blooms which create oxygen-starved ‘dead zones.’
Production of Methyl-Mercury: A Threat to Human and Wildlife Health
So far, we have discussed the environmental and ecological impacts of dams. Now, let’s look at some key facts, summarized in the table below:
| Direct Impacts of Dams | Indirect Impacts of Dams |
|---|---|
| Habitat fragmentation | Climate change |
| Flooding & habitat destruction | Destruction of food chain |
| Downstream erosion | Alteration in biodiversity |
| Reduced wildlife support | Creation of dead zones |
One of the most alarming effects of dam creation is the production of methyl-mercury. The stagnant water in reservoirs facilitates the transformation of inorganic mercury into methyl-mercury due to decomposing organic matter from decaying plants. This compound accumulates in fish living in the reservoirs, causing toxic effects in both humans and wildlife that consume these fish.
