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Water Supply and Ecosystem, Affected by the Construction of Dams and Reservoir

Construction of larger dams tends to be expensive causing taxpayers to be burdened / Photo by Wikipedia

 

A water dam is a barrier that stops or restricts the flow of water or underground streams. The reservoir created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Dams provide a range of economic, environmental, and social benefits, including recreation, flood control, water supply, and hydroelectric power.

However, despite the benefits that dams and reservoirs provide to most communities, it also poses a threat to the ecosystem and to the supply of water. Large dams have forced some 40-80 million people away from their lands in the past six decades. The indigenous, tribal, and peasant communities have been very affected when large companies and the government decided to create huge dams on their native land.

The environmental consequences of large dams are numerous and varied, and it also includes a direct impact to the biological, chemical, and physical properties of rivers and other species who live near the body of water. Environmental groups are concerned by the construction of dams and reservoir in the migration of fishes and other natural water inhabitants that thrive on those bodies of water.

Constructing a dam also tend to be extremely expensive to build and the cost is so high which the taxpayers will be burdened of. The operation alone is costly and it needs a lot of funds and manpower in order for it to work efficiently. Although it helped in preventing floods, it also affects the natural environment by suppressing the amount of water that flows on rivers and streams.

Water Consumption

According to a webpost by Nature, environment preservation activists and experts continually argue whether dams and reservoir poses a larger threat in the supply chain of water rather than making it a lot easier to consume. Concerned environmental experts believe that reservoir could make drought worse by preventing the natural flow of water.

Many urban areas of the world are supplied with water abstracted from rivers pent up behind low dams or weirs. Dams are expected to affect water quality and quantity for millions of downstream users. Environmental experts suggested that by trapping river-borne nutrients, it could start the unnatural growth of toxic algae which could make the water unfit for consumption. Storing water for a long period of time could make the water lethal and it could endanger the lives of the people who rely on water companies which profit on dam storages.

Furthermore, Science Daily also shared that scientists from Uppsala University conducted a study which proves that the construction of water dam and reservoir is connected to the drought that the world is experiencing today. The scientists also argued about the supply-demand cycle where the exploitation of water supply could happen if the demand for more water supply is not met after new reservoirs and water dams are going to be built in the future.

 

Dams are preventing the natural flow of water resulting to drought worsening / Photo by ZSM via Wikimedia Commons

 

The Ecosystem

As fisheries become an increasingly important source of food supply, more attention is being paid to the harmful effects of dams on many fish and marine populations. The vast majority of large dams do not include proper bypass system for aquatic animals. This irregular cycle interferes with their lifecycles and it sometimes forces species to go extinct.

National Geographic also mentioned on their online article that large dams could also affect the natural migration of fishes while it also creates a new way for harmful and foreign species to attack and destroy the plants and animals that reside in that body of water.

A large dam can cause the loss of entire ecospheres, including endangered and undiscovered species in the area, and the replacement of the original environment by a new inland lake. Large reservoirs formed behind dams have been indicated in the contribution of seismic activity, due to changes in water load and the height of the water table.

Surface temperatures tend to become warmer as the slower moving or slack water absorbs heat from the sun. In addition to surface water warming, the colder water sinks toward the bottom because of its higher density. The colder water that sinks toward the bottom contains reduced oxygen levels.

Effect on Earth’s Topography

The construction of water dams involves riverbed deepening. This process lower groundwater tables along a river, and altering the riverbed also reduces habitat for fish that spawn in the river bottoms and for other invertebrates. Habitat conditions change and a new equilibrium emerges. As this happens, a different set of dynamics will begin to have an impact on different species that originally grow, nest, feed or thrive on those bodies of water.

Destroying the existing ecosystem balance which has taken thousands of years to create has its repercussions. One of the first problems with dams is the erosion of land. When sediments collect, the ecosystem can be affected in two ways. First, downstream habitat can decline because these sediments no longer provide important organic and inorganic nutrients. Second, an effect called “nutrient loading” can cause the supply of oxygen to deplete.

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