Water Dam Meaning, History, Types, Principle, Uses, and Impact
A water dam is an engineering structure which is built within a water body for the primary purpose of restricting and controlling the flow of water.
This article discusses water dams as outlined below;
-Water Dam Meaning: 6 Ways to Define Water Dams
-How A Water Dam Generates Electricity
-Environmental Impacts of Water Dams
Water Dam Meaning: 6 Ways to Define Water Dams
A water dam is a structure which is built across a river, estuary or stream, to retain or confine water.
The interaction between water dams and water currents is another important factor which can be given details when defining a dam;
A water dam is an artificial barrier which is constructed across a stream or river to obstruct water flow, increase water level, form a reservoir, and control subsequent water flow.
The above definition highlights the basic functions of dams in hydropower systems, which is given further light, as follows;
A water dam is one of the parts of a hydropower plant, which helps in the generation of hydroelectricity by restricting water flow, and creating a preferred flow pattern for driving a turbine generator.
Other uses of water dams are highlighted in the following definition;
A water dam is an engineering structure built across a water body, for purposes of water storage, flood control, irrigation, water supply, and electricity generation [12].
As indicated above, dams can be useful in flood control. The following definition better portrays the usefulness of water dams in this area;
A water dam is an artificial barrier that is built within a water body, and which helps to mitigate water-related manmade and natural hazards like flooding, severe erosion, and stormwater pollution.
Lastly, the types of water dams can be used to define them;
A water dam is a water retention and control structure, which is categorized into various types like diversion, gravity, buttress, embankment, arch, rockfill, steel, timber and coffer dams.
History of the Water Dam
Earliest records of dam construction usage surround the Jawa Dam which was built in Mesopotamia (modern day Jordan) around 3000 BC [2].
These records suggest that the original dimensions of the dam were 3.3 by 30 ft (width × height), although it is likely that these dimensions were increased with subsequent modifications of the dam.
The Jawa Dam made use of an innovative pressure-resistant design that included a supportive reinforcement structure behind the main barrier, that reduced the risk of a breach. However, other dams built in the ancient times were gravity dams with relatively simple and vulnerable designs.
Approximately four centuries later, the Sadd el-Kafara Dam was built in ancient Egypt, around 2950-2750 BC [5]. Alternatively known as the “Dam of the Pagans,” this structure was built primarily for flood control and water supply.
Dimensions of the dam were about 348 by 37 ft (width × height), and the components of the barrier were bound loosely using limestone. The dam was breached and failed before its completion, as a result of a storm event.
The Nimrod’s Dam, built in Mesopotamia around the year 2000 BC [1]. This water dam was built out of regolith material, and can be classified as an Earth dam. Flood control and water diversion were the two main functions of the dam.
In Yemen, construction of the Great Marib Dam commenced around 1750 to 1700 BC [10]. Its dimensions were 1,900 by 13 ft (length × width). These dimensions increased with subsequent repair and modification of the dam.
The Eflatun Pınar water impoundment structure was built between the 1600 and 14000 BC in Turkey. Beginning from the first century AD, gravity dams in Rome were built using mortar and concrete. Also in the first century AD, the Kallanai Dam was built in the Kaveri River in South India [4], and was used primarily for water diversion and flow control.
Around 251 BC, the Du Jiang Yan was completed [3]. It was used as an irrigation facility.
Kebar dam was built around 1280 AD in Iran, with dimensions of 180 by 85 ft, as one of the earliest arch dams.
By the second century AD, various innovative designs had been deployed by Roman architects in various parts of Eurasia. These designs included buttress, arch, and gravity dams.
In subsequent years, dam technology improved significantly, to include greater resistance and higher capacity. Dams became relatively common in Europe between the 10th and the 12th centuries.
Dam construction in Spain during the seventeenth century, introduced many innovative designs and methods. In 1736, Spanish engineer Don Pedro Bernardo Villarreal de Berriz published one of the pioneer academic materials on dam design [9]. This material provided ideas that were used in the building of sophisticated water dam systems.
It can be argued that the nineteenth century marked the onset of modern dam construction. In 1804, the Mir Adam dam was built as a water-supply facility in Hyderabad [8].
In the second half of the nineteenth century; parts of the United States such as California, experienced an increase in the prominence (based on construction, and capacity) of water dam technology, as a result of the gold rush that led to regional population growth.
During the 1820s and 1830s, the Rideau Canal was constructed in Canada, under the supervision of Lieutenant-Colonel John [11].
In 1902, the Aswan Low Dam was built in Egypt by the British [6]. This was one of the major, large dams built during this period, alongside the Hoover Dam, completed on the Colorado River, United States, between 1928 and 1935 [7].
Water dam construction has improved in the twenty-first century, with multiple purposes and designs.
Types of Water Dams
The types of water dams are gravity, masonry, arch, saddle, embankment, Weir, diversionary, tailings, dry, steel, coffer, timber and natural dams.
These can be broadly grouped into structure-classified, material-classified, and purpose-classified water dams.
1). Structure-Classified Water Dams
Any water dam which is defined and identified on the basis of its structural features, falls within this category.
Structure-classified dams include arch, masonry, gravity, and embankment dams.
2). Material-Classified Water Dams
Timber and steel dams are types of water dams that fall under this category.
3). Purpose-Classified Water Dams
Purpose-classified water dams include weir, diversionary, tailings, saddle, and dry dams.
How A Water Dam Generates Electricity
A water dam generates electricity through a process involving water impoundment, accumulation and controlled flow, whereby potential energy of the water is converted; first to kinetic energy, then to mechanical energy that is used to drive a turbine generator.
However, it is important to note that the water dam does not generate hydroelectricity single-handedly on its own. Rather, it is a component of a larger hydropower plant that includes penstock and turbine, among other components.
The three main steps involved in the generation of hydroelectricity by use of water which is controlled by a dam, are discussed below;
1). Water Impoundment
Impoundment is the most basic function of a water dam.
This is simply the restriction of water flow within the area cut across by the dam. Since a water dam is an artificial barrier, its presence across a water body, invariably leads to changes in the mode of fluid circulation within the water body.
Water dams are designed such that the restriction of flow meets certain requirements with respect to the intended use of the dam.
2). Water Accumulation
Accumulation is what typically occurs after the dam has been constructed and flow restricted.
As a result of impoundment, the level of water (or ‘water head’) within the restricted flow region will vary from the water level outside this region.
In general, the restricted area increases in level as it accumulates more water due to the restriction of flow. Water dam design projects include measures to ensure that the level of water which can accumulate within the restricted area is sufficient for the intended purpose (which may be agriculture, flood control, power generation, etc.).
3). Controlled Flow in a Water Dam
The final step in the hydroelectricity generation function of a water dam is controlled flow.
Basically, this refers to the release of water from the restricted-flow region in the water body.
When water accumulates in the restricted-flow area, it gains significant amount of potential energy. The water level also rises as a result of increase in volume, as it accumulates.
Upon flow, this potential energy is converted to kinetic energy, whose magnitude depends on both the volume of flowing water and the height of fall (from its initial level to a lower level).
Uses of Water Dams
A water dam often serves multiple purposes simultaneously. Major uses of water dams include electricity generation, water storage and flood control.
1). Electricity Generation as one of the Uses of A Water Dam
In electricity generation, a dam acts as an energy storage and conversion system.
As a component of a hydropower plant, the water dam enables the facility to capture and utilize water effectively by impounding and controlling the flow.
Alongside the turbine, a water dam is involved in the process of converting the potential energy of water to mechanical energy used to generate power.
2). Water Storage
Because of their ability to impound water and restrict flow, dams can be used for water storage.
In order to achieve this, a retention system or reservoir must be present alongside the dam, to actively and effectively collect the water.
Water storage by a dam-reservoir system is useful where the water is needed for irrigation and recreational purposes.
3). Flood-Control as one of the Uses of A Water Dam
The ability of a water dam to retain water, is what makes it useful in flood control.
Dams employed in flood-prone areas can mitigate flooding by holding large volumes of water during periods of high precipitation. The water withheld may later be released when precipitation and stormwater levels have decreased.
Environmental Impacts of Water Dams
A water dam can contribute to some forms of environmental degradation.
Within the aquatic ecosystem, restriction of flow by water dams; can reduce oxygen concentrations in some cases. This is detrimental, as all aquatic organisms require oxygen for survival.
In addition to reducing oxygen concentration, methane and carbon dioxide can be released in significant quantities from dam-restricted water due to relatively-unfavorable conditions of biodegradation. Such conditions can contribute to the greenhouse effect, global warming and climate change.
Migration of aquatic species is often affected by water dams, by altering the natural flow pattern of the water. In extreme cases this can threaten the survival of organisms that carry out migration as part of the behavioral adaptation.
Other possible environmental effects of dams include changes in the quality and physicochemical properties of water.
Conclusion
A water dam is an engineering structure which is built across a water body and acts as a barrier that restricts and controls the flow of water, for agricultural, recreational and industrial purposes.
Types of water dams include;
- Structure-Classified Water Dams
- Material-Classified Water Dams
- Purpose-Classified Water Dams
A water dam generates electricity in three steps, which are;
- Water Impoundment
- Water Accumulation
- Controlled Flow
The working principle of water dams is fluid flow restriction and control.
Uses of water dams include;
- Electricity Generation
- Water Storage
- Flood-Control
References
1). Adamo, N.; Al-Ansari, N. (2020). “In Old Babylonia: Irrigation and Agriculture Flourished Under the Code of Hammurabi (2000-1600 BC).” Available at: https://www.researchgate.net/publication/339782821_In_Old_Babylonia_Irrigation_and_Agriculture_Flourished_Under_the_Code_of_Hammurabi_2000-1600_BC. (Accessed 30 June 2022).
2). Adamo, N.; Al-Ansari, N.; Sissakian, V. K.; Laue, J.; Knutsson, S. (2020). “Dam Safety: General Considerations.” Available at: https://www.researchgate.net/publication/342270305_Dam_Safety_General_Considerations. (Accessed 30 June 2022).
3). Mertha, C. M.; Lowry, W. R. (2006). “Unbuilt Dams: Seminal Events and Policy Change in China, Australia, and the United States.” Comparative Politics Vol. 39, No. 1 (Oct., 2006), pp. 1-20 (20 pages). Available at: https://doi.org/10.2307/20434018. (Accessed 1 July 2022).
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6). Havnevik, K.; Oestigaard, T.; Beyene, A.; Ögmundadottir, H. (2022). “From Aswan to Stiegler’s Gorge – Small stories about big dams.” Available at: https://www.researchgate.net/publication/361256615_From_Aswan_to_Stiegler’s_Gorge_-_Small_stories_about_big_dams. (Accessed 1 July 2022).
7). Rogers, J. D. (2010). “Hoover Dam: Evolution of the Dam’s Design.” Hoover Dam 75th Anniversary History Symposium. Available at: https://doi.org/10.1061/41141(390)7. (Accessed 1 July 2022).
8). Ŝiŋģh, A. (2018). “Evolution of dams.” Available at: https://www.slideshare.net/ayushks1/evolution-of-dams. (Accessed 1 July 2022).
9). Turriano, F. J. (2016). “Renaissance engineers.” Available at: https://www.academia.edu/30479374/Renaissance_engineers. (Accessed 1 July 2022).
10). Vogt, B. (2004). “Towards a new dating of the great dam of Marib: Preliminary results of the 2002 fieldwork of the German Institute of Archaeology.” Available at: https://www.researchgate.net/publication/285170235_Towards_a_new_dating_of_the_great_dam_of_Marib_Preliminary_results_of_the_2002_fieldwork_of_the_German_Institute_of_Archaeology. (Accessed 30 June 2022).
11). Wylie, W. N. T. (1983). “Poverty, Distress, and Disease: Labour and the Construction of the Rideau Canal, 1826-32.” Labour / Le Travail, Vol. 11 (Spring, 1983), pp. 7-29 (23 pages). Available at: https://doi.org/10.2307/25140199. (Accessed 1 July 2022).
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