Reservoir

A reservoir is a big lake. We build a wall to hold water. This wall is called a dam.

A dam stops a river. This makes a big pool of water.

This water can help us. It can make power for our homes. It can also help plants grow in dry lands. Some lakes are even built near the sea. These help store water from rivers. Reservoirs are very useful for people.

A reservoir is a large lake made by people. Most reservoirs are built behind a dam. A dam is a strong wall that stops a river. This creates a big pool of water to store for later.

People use this water in many ways. Some reservoirs make power for our homes. This is called hydroelectric power. Other reservoirs hold water for farms. These are called irrigation reservoirs. They help plants grow during dry times.

There are different kinds of reservoirs. Some are built in valleys. These use the shape of the land to hold water. Others are built near the sea. These are called coastal reservoirs. They help store river water near the coast.

Some reservoirs are even underground. These are called service reservoirs. They store clean water close to where people live. They can be large tanks or even brick rooms.

Building a reservoir can change the land. Sometimes, people must move homes or old buildings. In the past, kings in Sri Lanka built huge reservoirs. They did not want to waste a single drop of water.

A reservoir is an enlarged lake made by people to hold water. Most are built behind a dam to store fresh water for many uses. Some reservoirs even help create hydroelectric power, which is electricity made from moving water.

These man-made lakes are very important for helping communities stay healthy. They can provide water for drinking, farming, or even just for fun. People use them to make sure there is enough water during dry times.

There are several different ways these water pools are made.

One common way is to build a dam across a narrow valley. The high sides of the valley act like natural walls to hold the water. Some reservoirs sit on the original riverbed, while others get water from a different path.

Another way is to build a coastal reservoir near the sea. These are helpful because they do not use as much land. They catch river water near the coast to keep it safe for later use.

Humans have been building these water stores for a very long time.

Around 3000 BC, farmers in Arabia used old volcano craters as reservoirs. In India, people built a reservoir at Girnar around the same time. Ancient kings in Sri Lanka also built huge reservoirs for their crops. King Parākramabāhu I wanted to make sure no water was wasted. In Yemen, the Sabaean kingdom built the Marib Dam way back in 800 BCE.

Reservoirs come in many different sizes and shapes. Some are huge, like the Hoover Dam or the Cherokee Reservoir in Tennessee. Others are much smaller, like bank-side reservoirs that sit next to a river.

Some service reservoirs are even built underground to stay close to people. The Honor Oak Reservoir in London was once the largest brick underground reservoir in the world. It was built between 1901 and 1909.

Building these large structures can change the world around them. Sometimes, people have to move their homes or even move old temples. For example, the temples of Abu Simbel were moved to make room for Lake Nasser.

Reservoirs also help clean water by letting dirt settle to the bottom. This is called retention time, which gives nature time to work. This helps make the water much better for people to use.

A reservoir is an enlarged lake created by humans to store water. These artificial bodies of water serve many vital purposes for civilization. They are most commonly used to store fresh water for human consumption. Many reservoirs also function as tools for hydroelectric power generation. This process uses the energy of moving water to create electricity.

By controlling watercourses, humans can manage how much water is available at different times. This helps prevent flooding and ensures a steady supply during droughts.

There are several ways to construct a reservoir.

Dammed reservoirs are a common type. They are created by building a dam across a valley. This method uses the natural topography of the land to form the basin. The valley sides act as natural walls for the water. Builders often place the dam at the narrowest part of the valley. This provides structural strength and reduces construction costs.

These can be on-stream, meaning they sit on the original riverbed. They can also be off-stream, which means they receive water from a diverted stream or a pipeline.

Other types of reservoirs serve more specific needs. Coastal reservoirs are built near river mouths on the sea coast. They are often preferred because they do not use scarce land area. Bank-side reservoirs are built next to rivers to store water of variable quality. These are often formed by excavating a pool and building an encircling embankment, or bund. Some service reservoirs are built as water towers on concrete pillars. Others are storage pools, tanks, or even underground cisterns.

These service reservoirs keep fully treated potable water close to where people live.

Building these massive structures has a long history.

Around 3000 BC, farmers in Arabia used extinct volcano craters as reservoirs. In India, a reservoir was built at Girnar around 3000 BC to manage water scarcity. Ancient Greece had artificial lakes by the 5th century BC. In the 11th century, the Bhojsagar lake was constructed in India. The Kingdom of Kush invented a type of reservoir called a hafir during the Meroitic period.

These hafirs helped provide water for drinking and irrigation during dry seasons. In Yemen, the Sabaean kingdom built the Marib Dam in 800 BCE.

Large-scale construction projects often require significant changes to the landscape. When a dam is built, people may need to be moved and re-housed. Historical artifacts and entire villages might be relocated. For example, the temples of Abu Simbel were moved to create Lake Nasser in Egypt. The village of Capel Celyn was relocated to build Llyn Celyn. The village of Borgo San Pietro was also moved for the Lago del Salto project. These changes are part of the complex process of managing natural environments.

Reservoirs also play a role in cleaning the water. When water is held in a reservoir, it experiences what is called retention time. This is the amount of time the water stays in the reservoir before being released. During this time, particles and silts can settle to the bottom. Natural biological processes also occur. Algae, bacteria, and zooplankton can help reduce contaminants. This makes the water much cleaner before it reaches a treatment plant. However, in some climates, this can lead to temperature stratification in the water.

Finally, reservoirs are essential for agriculture through irrigation.

Irrigation reservoirs are filled using pumped groundwater, river water, or runoff. They are typically used during the local dry season. This use of water has caused debates in places like France. Some people worry that these reservoirs can lead to a loss of ecological balance. They argue that the reservoirs might increase the severity of droughts. Proponents, however, see them as a way to support sustainable agriculture while waiting for better models.