Huge dams have resulted in the widespread devastation of forestry due to the sinking by reservoirs and the clearance of woodlands for the relocation of the local inhabitants. Pastures, forests, farmlands have been allocated to reservoirs, tanks, canals, artificial lakes and other infrastructure related to river valley schemes and developments. According to recent surveys, massive river valley projects have consumed about more than half a million hectares of plantation land between 1951 and 1976, which comes out to be one-tenth of the area that has aided from large irrigation projects. The rivers and the ecosystems they back are exclusive. This results in permanent ecological damage, caused by the construction of huge scale dams. The following are the consequences of the very same-
1) Alteration in water quality.
A) Rivers offer vitality and energy for some essential processes in downstream, deltas, estuaries, coastal areas, on which the life of the fisheries are highly dependent. These developments comprise transport of nitrogen, organic matter, nutrient-rich silt, and oxygen. Any water management scheme that lessens the flow of water by more than twenty-five percent will result in adverse effects on coastal areas, water channels, and fisheries, thus also resulting in subsequent diminution of fish catches. The effect is, even more, potent with advanced reactors of water flow.
B) Dams tend to collect the sediments eroding from the soil and rocks by the rivers. The clear water flowing below the dam tries to reduce its missing deposits and thus erodes the soil on the banks downstream from the dam. This loss of sediment is chiefly important on the delta of the rivers as it leads to further degradation of the coastal regions. The increase in the flow of deposits and sediments also adversely disturb the dam’s capacity for hydropower generation.
2) Loss of biodiversity
The most intense environmental consequence of a dam project is the submerging of enormous expanses of forests, wetlands, cultivated land, and wildlife into the water. According to estimations on a global scale around forty-thousand square kilometers of land has been flooded by such dams. Dams beside the Indus River have destroyed nearly all the deltas and mangrove forests. Countless species of plants and animals have become now extinct due to the flooding of their habitats after the construction of dams. Dams splinter the revealing ecosystem, detach the different species of wildlife from their respective habitats and cut off migrations and other environmental patterns essential for the survival of the flora and fauna. The natural network in the area of reservoirs and high power-consuming dams is disturbed. Submergence of these areas result in disappearance of plant and animal species distinctive to those ecosystem as was seen in Seoul Valley hydroelectric project of Kerala (the sole project that was efficaciously derailed by preservationists and environmentalists) and thus the damage to our biodiversity or biological resources, the assessment of which cannot be done right now.
5) Difficulties in constructing Dams
Dams may falter even in the absence of earthquakes and shakes due to poor construction, as was seen in Machu dam in Gujarat, which bust in the year 1979 resulting in massive destruction and death. A study by the World Bank, which has been the foremost sponsor of the construction of large dams in India, found that at least seventy percent of the dams funded by them have a thoughtful design, construction, assembly or other security related errors. Large dams and their reservoir upset the local ecosystem in numerous means, and such effects cannot be straightforwardly measured regarding monetary expenses and profits, but the loss of biodiversity is not factored into cost-benefits investigations.
6) Impact on Civilization.
A populace who have lost their property, livelihood and even homes because of large-scale expansion projects are called environmental refugees. The reason displacement of these people transpires so effortlessly is because it involves mostly poor peasants and tribal people. Unfortunately, these people are usually uneducated and unaware of their rights. They are moved out of their native habitats in mass numbers without even considering the economic and psychological impact of such movements on everyone. Hence, the dislocation takes place without the knowledge of the affected population, who do not have any role to play in the project nor do they get any share of the benefits provided afterward to the interested parties. This problem of displacement further complicated by the fact that even land acquisition records of the displaced population are not available, and thus there is no assurance that the reimbursements will reach the correct people.
A dense forest cover is extremely essential for restricting further soil erosion. However, catchment areas of dams frequently experience quick deforestation, causing landslides, heavier water currents and water streams into the reservoirs, and ultimately, a situation arises which ironically portends the proficiency of river valley projects themselves. High siltation rates over the period of years have radically reduced the life expectancy to the level of complete unsuitability for agriculture. These dams have caused immense evaporation loss, subsequently increasing the saline level in the water bodies to extremely unsafe levels. Reduction in the flow of water and silt produced by these large-scale projects have an undesirable bearing on downstream ecosystems and also badly affects the fertility of the nearby agricultural land. Delta areas and the agricultural lands in proximity to it suffer from ingress of the salty sea water. Reduced water flow in many rivers has also amplified the level of contamination, hence making river water unusable for humans and animals.
These few points prove that there urgently needs to be a widespread introspection of whether dams are making lives difficult or easy for us.Although dams can benefit our lives, they are also the root to the considerable detriment of rivers. Dams have exhausted fisheries, ruined river bio-networks, and lessened leisure activities on virtually all of the nation’s rivers and waterways. Today, many dams are timeworn, hazardous or no longer serve their envisioned targets or purposes.
For many of these dams where the adverse impacts of these on the river and waterside societies overshadow the advantages of the dam, dam elimination would surely be a sensible and rational approach to reestablish healthy rivers and river-bank populations.