Dam and Reservoir

The definitions and implications of the terms Dam and Reservoir are frequently misunderstood. Actually, the connotations of the two are rather different. Since the beginning of human civilization, humans have struggled to control the flow of water so that the appropriate amount of water can be delivered to the appropriate locations. Humans, for that matter, build dams and reservoirs all along the river's banks to control the river's flow and store water for various uses.

Dams and reservoirs are both built to control river flow and store water for irrigation and other uses. Because they have several characteristics, people frequently confuse a dam with a reservoir. Despite the fact that they are linked, they are not the same.

The article focuses on the description of the dam and reservoir, and the article then defines the difference between dam and reservoir. The article also covers a brief description of different types of dams and reservoirs. 

A dam is a structure placed over a river, stream, or estuary to keep or withhold water. Steel, rock, and wood are among the materials used to construct it. It is largely used to manage, conserve, and utilize water for specialized reasons such as the generation of power.

A dam is a structure that controls or stops the flow of water or subsurface streams. Reservoir, on the other hand, is an open-air storage space (typically built by masonry or earthwork) where water is gathered and stored in sufficient quantities to be drawn off for consumption.

Types of Dams

To have a better understanding of the difference between dams and reservoirs one must understand the basics of the different types of dams. These are summarised below.

• Gravity Dam

• Arch Dam

• Buttress Dam

• Embankment Dam

Gravity Dams

A gravity dam is a structure made of concrete or stone masonry that is meant to keep back water by relying solely on the weight of the material and its resistance to the foundation to counteract the horizontal pressure of water pushing against it. Each portion of a gravity dam is designed to be stable and independent of the other dam sections.

Gravity dams are often built on stiff, high-bearing-strength rock foundations (little weathered to fresh), though they have been erected on soil foundations in exceptional situations. The foundation's bearing strength restricts the resultant force's permissible position, affecting overall stability. In addition, the stiffness of the gravity dam structure makes it unforgiving of differential foundation settling, which can lead to dam cracking.

Gravity dams have a few advantages over embankment dams, the most important of which is that they can withstand minor overtopping floods without causing damage since the concrete is scour-resistant. 

Gravity dams have the problem of being subject to uplift forces, which operate as a destabilizing factor because of their vast footprint. Internal and foundation drainage systems can help to lessen uplift forces (buoyancy). 

The exothermic reaction of setting concrete occurs during construction. The plastic concrete expands as a result of the heat, and it can take decades to cool. The concrete becomes stiff and vulnerable to cracking as it cools.

Arch Dams

An arch dam is a concrete dam with a plan that curves upstream. The arch dam is constructed so that the force of the water against it, known as hydrostatic pressure, forces against it, straightening the arch and strengthening the structure as it pushes into its base or abutments. A tight canyon or gorge with steep walls of sturdy rock to sustain the construction and stresses is ideal for an arch dam. They require less building material than any other dam type since they are thinner, making them more cost-effective and practicable in distant places.

Buttress Dams 

A buttress dam, also known as a hollow dam, is a dam having a solid, watertight upstream side that is supported by a series of buttresses or supports on the downstream side at intervals. It is possible for the dam wall to be straight or curved. 

The majority of buttress dams are composed of reinforced concrete and are extremely heavy, causing the dam to sink into the ground. Water rushes against the dam, yet the buttresses are rigid and keep it from collapsing.

Buttress or hollow gravity dams were designed to hold water for cultivation or mining in locations where resources were few or expensive, but labor was cheap. In wide valleys where solid rock is scarce, a buttress dam is an excellent option.

The advantages and disadvantages of buttress dams have grown increasingly obvious as designs have become more advanced. Buttresses were initially used to strengthen the stability of a dam wall by the Romans.

With the patented technology of Norwegian-American civil engineer Nils F. Ambursen, slab concrete buttress dams became popular in the United States in the early twentieth century.

Embankment Dams

An embankment dam is a massive man-made structure. A complicated semi-plastic mound of varied compositions of soil, sand, clay, or rock is often placed and compacted to make it. It has a solid, impenetrable core and a semi-pervious waterproof natural coating for its surface. This renders the dam immune to erosion from the surface or seepage.

A dam of this type is made up of shattered, self-contained material particles. Rather than using a cementing material, friction and interaction between particles bonds the particles together into a stable mass.

The earth-filled dam (also known as an earthen dam or terrain dam) is built of compacted earth, whereas the rock-filled dam is made of rock. The shape of an embankment dam in cross-section resembles that of a bank or hill. To prevent water from leaking through the dam, most feature a central portion or core made of impervious material. Clay, concrete, or asphalt concrete can be used for the core.

For sites with large valleys, this sort of dam is a viable choice. They can be constructed on either hard rock or softer soil. The rock-fill for a rock-fill dam is blasted with explosives to break it up. Additionally, the rock fragments may need to be crushed into smaller sizes in order to fit into an embankment dam's size range.

What is a Reservoir?

A reservoir is a big open-air water feature that resembles a man-made lake or a water reservoir. It is usually created by constructing a dam or a wall over a river or a wide valley. It can also be formed by erecting dikes around a parcel of land and then diverting a portion of the river flow into that land.

A reservoir's water can be used for a variety of reasons, including irrigation, hydropower, consumption, and household use. Precipitation, rainwater runoff, and the flow of a river all feed it.

Reservoirs, which are defined as fluid storage spaces, can retain water or gases, including hydrocarbons. These are stored in ground-level, raised, or subterranean tanks in tank reservoirs. Cisterns are water reservoirs in the form of tanks. The majority of underground reservoirs are used to store liquids below the earth, primarily water or petroleum.

Types of Reservoirs

As we have understood the dam and different types of dams, we must understand the different kinds of reservoirs, which will allow us to develop an understanding of the difference between dams and reservoirs. The types of reservoirs are summarised below.

• Valley-dammed reservoir

• Bank-side reservoirs

• Service reservoir

Valley dammed reservoir is formed in valleys where mountainsides serve as reservoir walls, and a dam or artificial wall is constructed to keep the water. The valley walls operate as natural barriers, and the dam is built at the narrowest practicable location to offer strength and lower construction costs.

Bank-Side Reservoirs

Water is diverted from rivers or streams into an existing reservoir to create these dams. Water is extracted from an existing stream or river and stored in a neighboring reservoir, forming bank-side reservoirs. The primary purpose of service reservoirs is to store water for later use. Water towers and other tall structures are common sightings.

Service Reservoirs

A service reservoir is a large, clean water-holding container. After being treated in a water plant, filthy or contaminated water is stored in a service reservoir before being distributed to end consumers. 

Many service reservoirs are built as water towers, which are often raised buildings supported by concrete pillars in areas where the terrain is relatively flat. Other service reservoirs, particularly in hilly or mountainous areas, can be virtually fully subterranean.

Service reservoirs serve a variety of purposes, including keeping an adequate head of water in the water distribution system and supplying water capacity to balance off-peak customer demand, allowing the treatment plant to operate at optimal efficiency. Large service reservoirs can also be managed to reduce pumping costs by filling the reservoir at low-energy times of the day.

The difference between dam and reservoir are summarized below in the table.

Difference Between Dam and Reservoir

In conclusion of the article, we can say that we have learned about dams and reservoirs, and the difference between dams and reservoirs. We have also learned about the types of dams and reservoirs.