Dam construction is complex and usually requires the participation of a diverse group of professionals from various disciplines.
What is a dam?
A dam is a facility that increases or decreases the amount of water by storing the water flowing in the river. When it rains a lot, a lot of water flows into the river and floods occur, and on the contrary, if it does not rain, the water of the river dries up. Dams keep an eye on the river for a constant amount of water, making it always available to us.
Are all dams damming the river?
Like dams, weirs and floodgates regulate the water flowing into the river. You may be able to see weirs and locks in the rivers of your city. Dams and weirs mainly have the role of storing water, and the gate is usually closed, and in the event of a flood, the gate is opened to adjust the amount of water. The difference between a dam and a weir is its height. A dam with a height of 15 m or more is called a dam, and a dam with a height lower than that is called a weir. On the other hand, the floodgate is normally open because it acts as a dike, but in the event of a flood, it closes the gate and weakens the flow of water to protect the downstream.
Role of the dam:
The role of the dam can be divided into hydraulic control, maintenance of normal functioning of running water, water utilization, and power generation. Let’s look at each role.
- Flood control:
Dams protect us from flood damage by adjusting the amount of water so that the river does not overflow or die.
- Maintaining normal function of running water:
Even when the water in the river is low, dams will prepare the surrounding environment by flushing water so that ships can pass and the creatures of the river can live with peace of mind.
- Water utilization:
Dams deliver the water we need for our daily lives, as well as the water used in fields and factories. Thanks to this role, water can be used regardless of the amount of rain.
- Power generation:
We use the natural power of the water stored in the reservoir to flow down to generate electricity and deliver it to your home.
What kind of dams are there?
Dams come in a variety of shapes and structures. Let’s look at typical types of dams:
- Gravity concrete dam:
Among the concrete dams, it is the most built dam. It has a structure that supports the force of water by the weight of the dam, and is triangular when viewed from the side. It is built on hard ground that can support heavy embankments.
- Arched concrete dam:
The embankment is thinner than the gravity concrete dam, and it has an arched shape. Due to the structure that distributes the power of water to both sides of the dam and the bedrock, it can only make a solid bedrock.
- Hollow gravity concrete dam:
A dam is hollowed out in a gravity-type concrete dam to save concrete. Because it is not heavy, it has a solid shape.
- Buttress dam:
It is a dam that supports a still wall to which water pressure is applied with a buttress.
- Trapezoid-shaped CSG dam:
It is a dam made by adding cement and water to materials obtained near the dam site, such as sand and rock scraps generated by excavation.
- Zone type fill dam:
It is a dam made of rock and earth and sand and is also called a rockfill dam. The rock part is responsible for the stability of the embankment, and the central part of the earth and sand that is difficult for water to pass through dams the water.
- Uniform fill dam:
Also called an earth-fill dam, it is the oldest dam made by compacting soil. The feature is that the embankment is lower than the rockfill dam. It is also the most numerous dam, accounting for about 70% of the world’s dams.
Explanation of Dam Construction Process:
As we mentioned earlier, dams are indispensable equipment for water storage, water volume control, and power generation. Without a dam, when it rains heavily, the river will overflow and flood and if it doesn’t rain for a long time, you won’t be able to get the water you need.
Here, let’s take a look at the dam construction process that is indispensable to our lives.
- Preliminary survey:
Preliminary surveys are conducted before starting a full-scale survey on dam construction. Preliminary surveys include planning surveys such as hydraulic control plans, explanations to the local community, geological surveys, and rough design of dams. Through a preliminary survey, we will confirm whether the necessary conditions for dam construction are met.
- Field plan survey:
If it is determined that there is no problem with the dam construction as a result of the preliminary survey, the field plan survey will be started.
In the field plan survey, we will conduct a more detailed survey than the preliminary survey while receiving a national treasury subsidy.
Specifically, this includes detailed geological surveys.
- Local negotiations:
Local negotiations are conducted in parallel with the on-site planning survey. During the dam construction, it will have a great impact on the surrounding area. Changes after the dam construction is complete are also very important to the region. Therefore, in local negotiations, officials from the national, prefectural, and municipal governments explain in detail to the local people. In addition, the necessary land must be handed over for dam construction. This will also be negotiated with the local people.
After the on-site planning survey is completed, the actual dam construction will finally be carried out. When the construction project starts, a transportation route for construction will be created first.
Once the transport path is complete, temporary commutation to allow water to flow during dam construction, foundation excavation to expose the foundation ground, secondary commutation to allow water to flow inside the dam, concrete production and transportation, and the dam. The process will proceed in the order of dam construction for the main body construction.
In addition, a detailed survey design and land survey/acquisition/compensation will be conducted at this stage.
How many dams are under construction in Pakistan?
A dam, according to experts, is a critical component in the creation and administration of water storage. Multipurpose dams, on the other hand, are particularly important in developing nations like Pakistan because they provide additional economic advantages and improve citizen welfare.
The Water and Power Development Authority (WAPDA) is now working on various dam projects as part of the federal government-backed ‘Decade of Dam’ plan. These dams are anticipated to be finished by 2028, according to the initiative’s basic planning and structure.
Diamer-Bhasha Dam, Mohmand Dam, Dasu Hydropower Project, Sindh Barrage, Nai Gaj Dam, and K-IV Project are already in the works. One by one, these large-scale hydropower projects will be finished and put into service.
Dam construction requires a construction period of about 10 to 20 years.
Also, once the dam construction is completed, that is not the end.
After the dam is completed, a test flood will be conducted to confirm its safety, and several staff members will be assigned to actually operate the dam.
Furthermore, when building a dam, it is necessary to construct equipment around the dam such as a park. From these aspects, it can be said that dam construction is a fairly large-scale plan.