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Updated on 10th March, 2023 , 7 min read
Dams are one of the most magnificent and well-known features of modern infrastructure. Dams have played an important part in the expansion and evolution of civilization throughout history. Several ancient city designers depended on dams to channel water through their towns despite their remote location, but military leaders exploited dams to modify the area in which they intended to battle. With the growth in population and their insatiable wants, humanity began to build dams to hold extra water from rainfall once it entered the river stream. Dams are used to generate hydroelectricity in addition to storing water for direct use. Dams may also serve as tourist attractions; for example,the Nagarjuna Sagar dam in Andhra Pradesh is a popular tourist destination.
A dam is a structure placed on a river, stream, or estuary to save water. It directly contributes to the provision of enough water for human consumption, industrial use, and agriculture. Modern dams are broadly grouped into two types-
Concrete or brick dams prevent streams from flowing through narrow gorges.
Embankments regulate streams and rivers flowing over large valleys.
The Nagarjuna Sagar Dam in Andhra Pradesh is an example of a masonry dam in India. The Tehri Dam in Uttarakhand is an example of an embankment dam in India. A huge portion of India's population is affected by a water crisis or poor water resource management. To begin with, many sections of the nation do not have adequate clean water for consumption or agriculture. Flash floods, on the other hand, are common in many areas. To address this recurrent issue, man-made structures such as dams and reservoirs have been built across streams and rivers.
The following are the 5 largest dams in India-
Dams, despite their numerous advantages, have a substantial number of drawbacks. The following are some of the disadvantages of dams-
Dams interrupt the normal water flow of rivers, disrupting the ecological balance of the related flora and animals. Environmentalists, human rights advocates, and concerned indigenous people have repeatedly protested dam development. The Narmada Bachao Andolan is a well-known social campaign spearheaded by locals opposing multiple dam development projects along the Narmada River, which is considered the lifeline of the Indian states of Gujarat and Madhya Pradesh. Dams, particularly large ones, can generate a slew of issues in the surrounding region, particularly in the zone behind the dam as the water rushes towards the obstruction. Some of the major disadvantages of dams that impact the environment are as follows-
Downstream reservoirs envelop the surrounding areas, flooding the habitats of the living forms that co-existed on the river's banks. This type of invasion damages plants and displaces wildlife and humans, lowering the overall quality of fauna and flora.
Dams provide an artificial barrier to flowing rivers and the aquatic life that lives in them. particularly migratory fishes that nest and reproduce upstream and downstream along the river. This has a direct impact on the species' population and, as a result, reduces the number of preceding and succeeding life forms in the food chain. Dams must be specially designed to allow fish and other species to get over them.
There are several detrimental consequences for aquatic life. Because dams obstruct the flow of moving bodies of water, such as rivers, any creatures that rely on the flow to breed or as part of their life cycle are endangered. Migratory fish that mate in a completely different place from where they live the remainder of their lives, for example, are unable to reproduce and may go extinct. Water accumulation is also hazardous to flowers that grow on the water's natural limit. Plant life may become submerged and perish.
It occurs as rivers and streams deposit sediments, enhancing the fertility of the soil along the banks. Yet, when the dam is built, the sediment load is deposited behind the dam, forming new deltas, banks, braided channels, and so on. Plant life and distribution are affected by variations in sedimentation.
Sediments that would have settled downstream accumulate behind the dam. As a result, it reduces the sediment load downstream and promotes downstream erosion. Because of the absence of silt, the riverbed deepens and shrinks with time. During the first decade of damming, this riverbed deepens by several meters. Changes in sediment buildup have a detrimental influence on a variety of physical processes and downstream life forms' habitats. Also, seasonal farmlands that developed before as a result of downstream sedimentation are becoming increasingly rare.
The stagnant water in the reservoirs is remineralized and can serve as a source of methylmercury. The reservoirs generate an environment in which decaying organic matter may convert mercury into methyl-mercury. Methylmercury is an exceedingly poisonous chemical that accumulates in plants, aquatic creatures, and people.
The submerged region near dams kills trees and plants, and their decomposition depletes the oxygen content in the water. Because the decomposition of plants and trees releases a significant quantity of carbon into the atmosphere. When stagnant river water depletes natural oxygen levels, a situation emerges in which methane, a greenhouse gas, is created at the bottom of reservoirs and eventually released into the atmosphere, contributing to global warming.
Along with lowering the quality of life in and around the dam, it has also had an impact on the people who live around the reservoirs. The following are some of the effects of dams on people-
Residents in the depression zone are frequently displaced when water from reservoirs encroaches on their houses and properties. And they lose their farms and companies, causing an economic downturn. In certain circumstances, indigenous people are forcibly evicted in order to acquire land for dam building.
When reservoirs reach dangerously high levels, dam managers unleash floodgates, potentially causing an untimely flood downstream. These man-made floods have an impact on city transportation and economic loss.
As witnessed in the case of the Hoover Dam in the United States. The dam's construction caused regular earthquakes and lowered the earth's surface. This is very concerning, as it would otherwise result in widespread damage.
Old dams are known to burst and bring massive floods down the river, killing many people. Despite the fact that new technology and safety standards are addressed in freshly built dams.
It continues to be an expensive and time-consuming operation. In India, a dam project might cost anywhere from Rs 372 crore to Rs 7,777 crore, imposing a financial strain on the country.
Dams that are erected over rivers that run between two countries have generated national disputes. The dammed river may cause water scarcity in neighboring countries, prompting them to respond. As shown in the cases of India and Pakistan, or West Bengal, India's easternmost state, and Bangladesh.
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By - Nikita Parmar 2024-09-06 10:59:22 , 6 min readAns. Dams create an artificial barrier between moving rivers and aquatic life, particularly migratory fish that nest and reproduce upstream and downstream along the river. This has a direct impact on the species’ population and, as a result, reduces the number of preceding and succeeding life forms in the food chain.
Ans. Stagnant water in reservoirs remineralizers and can serve as a source of methyl-mercury. The reservoirs generate an environment in which decaying organic matter may convert mercury into methyl-mercury. Methylmercury is an exceedingly poisonous chemical that accumulates in plants, aquatic creatures, and people.
Ans. The legislation aimed at the monitoring, inspection, operation and maintenance of the designated dam is known as the dam safety act. This legislation prevents dam-failure-related calamities and also provides an institutional system to oversee the dam’s safe operation.
Ans. The Three Gorges Dam, located in China, is the world’s biggest dam. It is a hydroelectric gravity dam that crosses the Yangtze River.
Ans. Earthquakes are caused by enormous reservoirs, a process is known as reservoir-induced seismicity. This is mostly determined by the water pressure caused by the dam’s tiny fractures and fissures. The earthquake happens as a result of the reservoirs prematurely releasing tectonic strain.