Facts about Dams: History, Physical Structure and Hydroelectric Power Generation

A dam is a structure built across rivers and other water bodies to hold water and regulate it for different purposes. The water stored in the dams is used for power generation in irrigation, hydroelectric power plants, flood control and for maintaining water supply. Humans have always been relying on reservoirs for water supply. They have undoubtedly been among the important structures built in history by different civilizations. Let’s explore some interesting facts about dams including its types, uses and benefits.

Table of Contents

• What are Dams
• When did People Start Building Dams
• Hydroelectric Power Generation and Other Benefits of Dams
• How Dams are Built
• Interesting Facts about Dams

What are Dams

The word dam comes from Dutch word Dammaz meaning to stop or block. A dam can be defined as a massive reservoir built into front of a river to hold water and transfer it to various places to serve different purposes such as harnessing the flow of water to produce electricity. Storing water in dams is one of the main ways to maintain fresh water supply for household and industrial use. 

When did People Start Building Dams

Dams are historically significant in serving people for over 5,000 years. Different civilizations including Assyrians and Babylonians built dams for irrigation. Egypt has one of the oldest dams named Sadd el-Kafara built in 2600 BC. There are ruins of dams found in the Middle East and in the Indus valley near Sindhu river. Unlike modern concrete dams, the dams built during the old times were simple in structure and were built with stones and rocks to hold water. Today, dams are seen as important infrastructures to harness energy from renewable sources.

Hydroelectric Power Generation and Other Benefits of Dams 

From irrigation to power generation, dams have many significant benefits in our life. Here are some major uses and benefits of dams: 

Renewable Energy Source: Hydroelectric power generated by using the kinetic energy of flowing water in dams is a renewable and clean source of natural energy. It emits very low carbon and doesn’t contribute to global warming as compared to fossil fuels.

Flood Control: Dams help to store water overflowing from rivers that can cause flooding. The water stored in reservoirs can be released slowly reducing the chance of sudden overflow and flooding.

Fresh Water Supply: The water stored in dams serves millions of people in different ways. It is used for municipal, industrial and agricultural use. During summers when rivers dry up the water stored in dams is the main source of water supply in dry areas.

Agriculture and Recreation: Most of the dams in rural areas are used for providing water for agriculture to grow crops and other food. Dams also promote recreational activities such as fishing and aquaculture.

So, whenever we use water from your tap, switch on a bulb or eat food grown on irrigated land we can think of the contribution of dams in our life.

How Dams are Built 

Planning and Digging: The ecologist and engineers first study the river and impact of construction on wildlife to purpose the well-suitable place for building dams. Then the water from the river is rerouted with the help of a diversion tunnel and a cofferdam which is a small temporary structure to move water away from the construction site. 

Solid Foundation: Once the bottom of the river dries, a strong foundation is laid at the with steel rods put deep between the rocks and sealed with a liquid cement called grout. After the grout sets, it seals the foundation of the dam firmly.

Building Walls of the Dam: Depending on the type of river and hydraulic pressures engineers decide to build the different types of dam walls including gravity, arch or buttress wall. Choosing the right kind of wall ensures the structural stability and strength of the dam.

Adding Emergency Doors: The water stored in the reservoirs is released through these doors in case of river overflowing. There are pipes too to supply water through them to towns or to animals downstream.

Filling Water: After the construction material is completely firm and dry, the temporary channel is closed and the river starts flowing again through its usual path, filling the reservoir for the functioning of the dam.

Interesting Facts about Dams

• Three Gorges dam in Hubei, China is the largest dam of the world holding 39.3 cubic meters of water.
• Jawa dam is the oldest dam built in 3500-3000 BC by an ancient settlement in Jordan.
• Dams can have both favourable and non-favourable ecological impact.
• Usoi Dam in Tajikistan is the tallest natural dam with a height of 1.860 feet.
• Hydroelectric power plants built on dams contribute to around 15% of the world’s power supply.
  
  

What are three different types of dams?

Three types of dams are gravity dam, arch dam and embankment dams. 

• Gravity dam: It is made of concrete or masonry that uses its own weight to resist the push of water. An example is Bhakra Nangal dam in India.
• Arch dam: It is an arch shaped curved dam that transfers force to the surrounding valley walls. For example, Hoover dam in the USA.
• Embankment dam: Build with gravel, dirt, sand and rocks a massive wall of compacted material in the middle that riles on its weight to resist water pressure. An example is Tehri dam in India.