What is Dam ?

The earth core is placed against a dumped rockfill. It is necessary to provide adequate filters between the earth core and the rockfill on the upstream and downstream sides of the core so that the soil particles are not carried by water and piping does not occur.

Dams trap 40 cubic kilometers of sediments every year, and starve deltas of the silt that protects them against the intruding sea.

No sites are totally free from jointing. Hence, sites cannot be abandoned, even if profusely jointed. However, the detailed mapping of all the aspects and characters of jointing as developing in the rocks of proposed site has to be taken up with greatest caution. The geometry of joints, their intensity, nature and continuity with depth, all must be thoroughly established and their effects on the site rocks evaluated and remedial measures taken in advance.

The earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC.

The Gariep Dam was designed to be a hybrid gravity-arch dam as the gorge is too wide for a full arch. Gravity abutments are formed using flank walls then the design gradually arches at the center of the dam. It impounds the Orange river and creates the Gariep reservoir with a maximum capacity of 5,340,00 megaliters. 899 GWh of electrical power is produced by the dam annually using 4x90 MW turbines. The Gariep Dam bridge is also visible from the photo below, where the Orange and Caledon rivers flow through as well the Brakspruit, Broekspruit, Oudagspruit, and Slykspruit streams.

The side slopes of rockfill are usually kept equal to the angle of repose of rock, which is usually taken as 1.4:1 (or 1.3:1). Rockfill dams require foundation stronger than those for earth dams.

Dams generate 16% of the world’s electricity and irrigate food crops for 12-15% of the world’s population.

Occurrence of micro-joints has to be established with still greater care as such joint systems, if left untreated, could be source of many risks. In the limestone rocks that formed foundation and abutments at Salal Dam in Jammu (Kashmir), the micro-joints presented considerable difficulties in detection and treatment.

There are many other dams around the world with their unique and fascinating engineering designs. So, if we've missed them then feel free to let us know in the comments section below.

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An arch dam is curved in plan, with its convexity towards the upstream side. An arch dam transfers the water pressure and other forces mainly to the abutments by arch action. An arch dam is quite suitable for narrow canyons with strong flanks which are capable of resisting the thrust produced by the arch action.

To a lesser extent, dams have also been built for water supply, flood protection, navigation and tourism purposes. Most dams have been built for irrigation, but 80% of the water they store is used for hydropower.

The word dam can be traced back to Middle English, and before that, from Middle Dutch, as seen in the names of many old cities

The determination of strength of the foundation rocks in the case of gravity dam and also of abutment rocks in the case of arch dams are considered starting points in working out designs of these dams. In either case construction of a dam involves transfer of a tremendous load due to the weight of the dam and weight and thrust of stored water on to a very small area of foundation or abutment rocks.

The section of an arch dam is approximately triangular like a gravity dam but the section is comparatively thinner.

Dams block the migration of fish, deplete rivers of oxygen, and interfere with the biological triggers that guide fish. They also reduce the ability of rivers to clean themselves.

The first known appearance of dam occurs in 1165. However, there is one village, Obdam, that is already mentioned in 1120.

The arch dam may have a single curvature or double curvature in the vertical plane. Generally, the arch dams of double curvature are more economical and are used in practice.

These loads are both of compressive and shearing nature. The capacity of the rocks vis-ά-vis these loads has to be clearly established. This is achieved by testing the strength properties in the laboratory on the core samples obtained from different and critical locations at the site using conventional laboratory techniques.

The word seems to be related to the Greek word taphos, meaning "grave" or "grave hill"

Due to dam building and other factors, the population of freshwater species declined by 37% between 1970-2008 - more than the populations of any other ecosystems. Tropical freshwater populations declined by a stunning 70%.

These loads are both of compressive and shearing nature. The capacity of the rocks vis-ά-vis these loads has to be clearly established. This is achieved by testing the strength properties in the laboratory on the core samples obtained from different and critical locations at the site using conventional laboratory techniques.

Examples of Arch dam: Hoover Dam (USA) and Idukki Dam (India)

So the word should be understood as "dike from dug out earth". The names of more than 40 places (with minor changes) from the Middle Dutch era (1150–1500 CE) such as Amsterdam (founded as 'Amstelredam' in the late 12th century) and Rotterdam, also bear testimony to the use of the word in Middle Dutch at that time.

About 50,000 dams with a height of 15 meters or more and millions of smaller dams have been built on the world’s rivers. Some of them date back centuries, but most were built after World War II. About 5,000 dams have a height of 60 meters or more; another 350 such giants are currently under construction.

Dams are not climate-neutral. Particularly in the tropics, organic matter rotting in their reservoirs emits methane, an aggressive greenhouse gas.