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WHAT IS A DAM

Dams are man-made or artificial barriers usually constructed across a stream

channel to impound water. Dams are typically provided with spillway systems tosafely pass a broad range of flows over, around or through the dam.

Various materials are used for dam construction such as timber, rock, concrete,

earth, steel or a combination of these materials. However, in Connecticut, most

dams are constructed of earth or combinations of earth and other materials.

Spillways are commonly constructed of non-erosive materials such as concrete or

rock.

Dams are typically constructed with a drain or similar mechanism to control water

levels in an impoundment for normal maintenance or emergency purposes.

The Department of Environmental Protection (DEEP), Bureau of Water Protection

and Land Reuse's Inland Water Resources Division, maintains a computerized

inventory of over 4,000 dams in Connecticut. Of these, approximately 1,500 fallunder the Department's regulation since their failure may cause loss of life or

property damage. The remaining dams are typically small and do not pose a

significant hazard to the public. The ownership of Connecticut's dams is diverse.

Approximately 84% (percent) are held privately and the remainder are held by

public or non-profit entities. Over 40 flood control dams in the state are owned and

operated at the federal and state level. The DEEP holds title to more than 200

dams, most of which are located in state parks and forest areas.

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DISADVANATGES:

1. Dams are extremely expensive to build and must be built to a very high

standard.

2. The high cost of dam construction means that they must operate for many

decades to become profitable.

3. The flooding of large areas of land means that the natural environment is

destroyed.

4. People living in villages and towns that are in the valley to be flooded, must

move out. This means that they lose their farms and businesses. In some countries,

people are forcibly removed so that hydro-power schemes can go ahead.

5. The building of large dams can cause serious geological damage. For example,

the building of the Hoover Dam in the USA triggered a number of earth quakes

and has depressed the earths surface at its location.

6. Although modern planning and design of dams is good, in the past old damshave been known to be breached (the dam gives under the weight of water in the

lake). This has led to deaths and flooding.

7. Dams built blocking the progress of a river in one country usually means that the

water supply from the same river in the following country is out of their control.

This can lead to serious problems between neighbouring countries.