Dams are technical works

Dams are technical works


1.1 Introduction

The dams are technical works which are constructed perpendicular to the bed of a natural stream (river), to prevent the flow of the water, in order to store it, or discharge it, or to use it for hydroelectric energy.

The functionality of the dams varies, as long as they offer invaluable benefits to the humans. The dam construction was one of the first and most important achievements in civil engineering. For many years the dams are used in order to fulfil needs of the everyday life and their use gives the humans many resources, such as water supply for irrigation and agricultural purposes. So one key component is the water storage for water supplies and irrigation. The dams also as it is mentioned before, allow the production of cheap electricity, in order to reduce the problem of distribution of electricity. In addition the energy produced does not cause environmental pollution, and there is possibility of energy storage when is needed. The dams can ensure effective flood protection, and they contribute to the maintenance for a clean environment.

One of the main problems is the alteration of the landscape. The bulky and inelegant structures, the dams, cause the destruction of the natural beauty of the environment and the existence of the concrete in natural landscapes and ecosystems is not very good, as concrete is not sustainable material and not renewable. Additionally the risk for local earthquakes is increased, wherever there are dams, due to the excessive loading of the earth's crust. The dams have undoubtedly offered many advantages along with the disadvantages. What is needed in order to ensure the balance is that before any dam construction environmental surveys must be done always based in the existing conditions of each area. By maintain such surveys, potential problems which could be fatal in the future, can be avoided.

1.2 Historical Background

From thousands years ago, humans were trying to control water and its levels in order to be benefited from its power and resources that it could offer them. So the humans started to construct prehistoric structures, the dams in order to maintain the water levels at desirable levels so they can use its power and its resources, and for irrigation purposes. There are some examples in China, Japan, India, and Shri Lanka, which still exist.

One typical example of ancient dams is the dam which is built in Sadd-el-Kafara, in Egypt around 2600 BC. See at figure (). Its name is taken from its own place where it is built. The ruins of this dam were discovered 100 years ago and surveys prove that it was 14 meters high and 113 meters along the crest. It is constructed from a rock fill zone, flanked by rock shoulders and with rubble masonry face protection. According to surveys that have been achieved, it is the oldest of such a size dam, known in the world and its purpose was to hold back the water from the rare and catastrophic floods. Finally the dam was breached, probably due to flood overtopping.

There are some other dams similar to the one mentioned above, which are constructed in the Middle East, Saudi Arabia, Iran and Iraq. For example the embankment dam Marib in Yemen, was built in 750 BC. for irrigation purposes, and its height was 20 meters, see at Figure (). Around the same period seems to be constructed another dam located in Turkey the Kesis Golu, which is 10 meters high.

Additionally the Romans have also constructed dams by helping countries in the Middle East and countries around the Mediterranean. Romans according to ‘Hydraulic structures, P. Novak third edition' seems to be the first who invented the concept of Arch Dams and a very good example for this is the Baume Arch Dam, which is located in France. See at Figure ().

It was designed and constructed by the Romans during the century AD. According to the ‘Cracking Dams' site, its purpose was to supply the nearby city. From a structural point of view this dam was one incredible achievement at this period of time, because it was 12 meters high and 18 meters long, with radius of 14 meters and central angle of 73 degrees.

Generally the dams are very useful. First of all they can generate electric power with low cost and in a feasible and environmental friendly way. So the electric power produced at these ages in the past, helped the societies to become more developed and more comfortable for living.

After some years the evolution of dams came, and from a structural point of view they became more developed and more necessary for the civilizations. This development gave the chance to the civil engineers to study and research more about the dam engineering, and they realised that the dam construction depends on several factors which are: The geological conditions and the soil properties of the site, health and safety during and after the construction of a dam, cost for construction and the maintenance, etc. All of these were the cause that civil engineers created several different types of dams, in order to choose the best solution for each case.

Generally the dams are separated into two big categories, the Concrete Dams and the Embankment Dams. This separation has been made according to the materials used for each dam type. The two previous categories of dams are separated into sub-categories.

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