Pros and cons of dams
Dams epitomize human innovation and ingenuity to make the most of the available resources to further progress. It is an ancient technology. The world’s first Dam, the Jawa dam, dates 3,000 BC. Now, dams face increasing critique as the debate rages between preservation of ecosystems versus demand for water, energy and consequent economic development. Here we examine them, the pros of dams and the cons of dams.
Purposes of Dams
Dams are chiefly made to facilitate irrigation and power generation. They serve as a source of water supply, mechanism for flood control, recreation and for fish farming. In few instances, dams are also used to facilitate travel routes and to control hazardous materials such as mine tailings and harmful sedimentation.
Construction of a Dam
The construction of dam results in a significant alternation of the natural local terrain before and after its construction. This in turn has an even greater impact on the local environment. To construct a dam, the river is redirected for the construction to take place. This may be done by digging trenches or blasting through the terrain. The diversion of the river creates an artificial reservoir with an unnatural and unsustainable temporary ecosystem. Main features of all dams are hydraulic apparatus, storage system and mechanism for controlled release of water. Comprised of these, the most common dam types are buttress, arch, gravity and embankment dams and the type of construction depends mainly on the terrain and purpose of the dam. Most dams are single purpose. Technological advances mean more multi-functional dams are being constructed.
Pros of Dams
Foremost is power generation. Hydroelectricity produced by the dam is a clean energy source. It is renewable, economical, safe and does not pollute the environment. Hydroelectricity accounts for 20% of the world’s electricity.
Dams store water which can in turn be used for a variety of other purposes. They provide access to drinking water and water for irrigation and household use. Especially under droughts and dry periods, dam water can make all the difference in farmers and their produce’s ability to survive the predicament.
By storing water and enabling it to be distributed as necessary, dams control floods. Thereby, they save crops, life and other property.
Benefits the presence of a dam offers to agrarian communities and their ability to carry out their tasks and prepare for the future and unexpected crises are immense.
The construction of a dam itself creates numerous jobs both before and after construction.
Lastly, through all the above, a dam brings about significant economical development.
Cons of Dams
The foremost critique of dams is from environmental preservationists who maintain that dams create an artificial local ecosystem and destroy the natural local ecology and habitat. The growth they bring about is thus unsustainable.
The natural river tributaries are destroyed when the dam is made and with them the flourishing local habitat and terrain. The local population must be relocated which can be very tedious and costly. Furthermore, aboriginal communities which may have been thriving in their natural habitat will be adversely affected by the change.
Dams may also block fish migration upstream and downstream. This will lead to deterioration in fish population and result in food shortages.
Dams also change the salinity of oceans and estuaries. The water quality is also suspect as algae formed on stored water surface can absorb nutrients and release large amounts of oxygen. The water develops an unpleasant taste and smell and does not remain fit for consumption or household use.
Compared to nature’s continuity, dams also have a very short lifespan. The mechanism of a dam is suspect to adverse effects through processes which directly affect the efficiency of the dam. Processes such as sediment buildup, overtopping, poor spillway capacity and seepage. Hoover dam is considered to have a limited life left, estimated to be less than 100 years, due to sediment buildup. Once filled with silt, a dam is less efficient and costlier to maintain. This raises the question, is it worthwhile for a temporary benefit to destroy the continuing local ecology which may not be able to adapt to the change?
Because of the negative impact it is likely that a less efficient dam will be dismantled. In the USA alone, between 1990 and 2015, around 900 dams were dismantled. The dam removal is a very costly process and the bigger the dam the costlier the removal. This is also a hidden cost which is often not factored in when measuring the productivity of the dam such as the cost of the electricity it produces.
A dam malfunction too poses a serious threat to population and property. A dam is a human innovation. It is subject to depreciation, deterioration or any miscalculation in its dynamics which may cause it to malfunction. Overtime, with better technology, the size of dams has increase massively. So too has the threat they pose due to malfunction. As was the case with Oroville dam, where damaged emergency spillways meant that over 180,000 people had to be relocated and communities along the dam’s influence suffered heavy losses. The dam’s malfunction was because of deterioration with time, poor maintenance and design flaws.
Dams on their own aren’t good or bad. They are an instrument offering much utility to mankind. The world’s insatiable demand for energy and diminishing usable water means dams are a necessity. But the world’s population is also growing more aware of its responsibilities. There is an ongoing quest for the least harmful, renewable and clean energy such as solar and wind energy, which are not detrimental to the environment. A dam is a mega-structure. It costs a lost. Requires a lot of effort and sacrifice. And has a massive impact both positive and negative. The advantages are spread out. The disadvantages tend to be constrained to the area of influence and are not easily reversible. It is not easy to classify whether we should add or remove dams or stop making them altogether. Absence of dams, symbolizes poor development rates of many less developed countries. It is a decision which must be visited with each prospective project and the circumstances governing it.
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