Environmental Aspects of Dam Construction and Operations

Sep 9, 2017   //   by admin   //   Knowledge Base  //  No Comments

Dam: A dam is massive wall creating a barrier in order to confine the water within its structures. This is a wall which halts the flowing water and creates a confinement that can further be used for several purposes such as irrigation, navigation, prevention of flood, usage of drinking water for people and most importantly creating a source for generation of electricity.

Types: there are natural dams made due to earth and rock fills forming a solid core of clay in the middle to prevent the leakage and outer layer of rock for strength.
Other dams are made of solid, concrete walls that resist the pressure of the water.

The dam wall creates a lake or reservoir which is used for multipurpose.

Water is a source of high amount of potential energy even when the water is in static state but carries high amount of kinetic energy when the water is in dynamic or state of motion.
Therefore in order to confine water, the wall needs to be constructed with solid material across the river valley so that it is watertight and provides safer , secured wall ensuring water doesnt escape. The strength of the wall needs to ensure resistance of water falling across the wall and capacity for storage of water.
Therefore, higher the wall, greater the depth of water stored behind it and greater is the pressure of the water on the wall.

If the monsoon is high or the river floods, water can escape this concrete wall and may spill away and reach the downstream. If the dam is built of concrete material, water may also spill over from the wall. There is always the danger of the water breaking the strength of the wall or if strength is ensured, capacity of water raises and spilling over its capacity limits.

Environmental Aspects: there are many sides of aspects that have been viewed when the construction of dam is considered. The construction of the dam leads to storage of water which creates a disrupting relationship between the land and water, destroying the natural eco-system balance.

Following are few of the adverse effects of dams on the environment.
1. Soil Erosion: dams hold back the sediments found in the running water creating a

deprivation for the downstream. In response to deprivation, the downstream

begins to erode its channels and banks impacting the lowering of riverbeds. This

therefore impacts the vegetation and wildlife.

  1. Species Extinction: it is realised overtime that annual flooding deposits nutrients

    and replenish wetlands. Many species also depend on floods for their cycle of reproduction and hatching which severely gets disrupted. Also since there is no provision of proper bypass, many marine aniamls and fishes are experiencing extinction.

  2. Rotation of Earth: Dr. Benjamin Fong Chao, a NASA Geophysicist has discovered with evidence that there is shift of water weight to reservoirs due to construction of many large dams. This is major reason of shift of earth’s daily rotation which could be detrimental in future by having adverse effects.

On contrary there are speculations over advantages of natural dams which are beaver dams that are a natural phenomeon. There is improvement in the environment quality and bio-diversity increases due to beaver dams forming lakes, ponds, meadows and wetlands.

Few of advantages of natural or beaver dams are:
Reduction in channel scouring and stream bank erosion. There is secured water supply improving the vegetation and wildlife. There is enlongated time in water retention in water cycle since the subsurface flow is slower than stream and river flow. When the dam slits, natural meadows form. This also improves canoeing.

It is therefore argued that confining the water

consistently in a man made dams could have more detrimental effects that much of advantages. However in cases of natural dams, the strong barrier doesnt confine the potentaility of water. Despite the environmental effects, dams can also proof to be highly high maintenance and problematic to human beings living in and around the region. Hence socially and environmentally the construction of dam needs to be considered.

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