Earthen Dams

Introduction

Earthen dams have been used for centuries to store water and generate power. They are a relatively simple structure, but they are still an important part of our infrastructure. In this article, we will discuss the history of earthen dams, how they work, and the benefits they provide. We will also talk about the potential risks associated with earthen dams and what can be done to mitigate those risks.

What Is An Earthen Dam?

An earthen dam is constructed from natural materials such as soil, clay, and rock. They are often used to store water for agricultural or municipal purposes.

Earthen dams are built by constructing a large mound of earth and other natural materials. The dam is then reinforced with a concrete or metal liner to prevent erosion and seepage.

Earthen dams are less expensive to build than other types of dams, but they are also less durable. They can be damaged by earthquakes or floods, and they may require frequent repairs.

Earthen dam types include:

• Rock-fill (or compacted earth) dams are made of compacted fill material, such as gravel, sand, or crushed stone. The most common type of earthen dam.
• Rolling-earth (or homogeneous) dams are constructed by placing alternating layers of soil and rock on a slope until the desired height is reached.
• Puddle clay dams are constructed by compacting a layer of wet clay on the streambed.
• Peat dams are constructed by building a dam of peat, which is an accumulation of partially decayed vegetable matter in bogs and marshes.

Pros And Cons Of Earthen Dams

The pros of earthen dams include:

• They are cheaper to construct than other types of dams.
• Earthen dams can be built quickly and easily, without the need for heavy equipment or specialized skills.

The cons of earthen dams include:

• Earthen dams have a shorter lifespan than other types of dams (typically only 25-50 years).
• They are less durable and more susceptible to damage from earthquakes, floods, or other natural disasters than other types of dams.
• Earthen dams may require frequent repairs due to erosion and seepage issues (this can be mitigated by using a concrete or metal liner).

Example Of An Earthen Dam In India: Banasura Sagar Dam:

The Banasura Sagar Dam is the largest earthen dam in India located in Wayanad, Kerala. It was built on the Kabini River and features a sub-merged Shola forest. It has been built to supply water for irrigation and hydroelectric power production. The dam is also a tourist attraction due to its natural beauty.

Components of Earthen Dam

Embankment Dam

Embankment dams are built by compacting earth to increase its strength and density. They can range from a few feet tall to as high as 300 feet (91 m). The tallest is the Nurek Dam in Tajikistan at 300 ft (91 m). The length of the dam also varies, from a few hundred feet to over a mile (1600 ft or 490 m).

Abutments

Abutments are the two ends of an embankment dam that rest on solid rock. They help to hold back the water and keep it from flowing around the end of the dam. The abutments also help to distribute the weight of the water on the dam.

Spillway

The spillway is a structure at the top of an embankment dam that helps control the flow of water. It is usually a wide, open channel with steep sides. The spillway allows excess water to flow out of the reservoir and keeps the level of the water from rising too high.

Outlet Works

Outlet Works is the structure that allows water to be released from the dam reservoir. It is usually a pipe or tunnel through which water can flow into the river below the dam. The outlet works are often used for irrigation, hydroelectric power production and other purposes as well.

Failure of Earthen Dam

The failure of an earthen dam can cause catastrophic damage, as seen in the case of the Banqiao Dam disaster. The collapse of the Banqiao Dam released a wave of water that caused extensive damage to downstream communities. More than 26,000 people died and another 145,000 were left homeless.

Conclusion

Earthen dams have been used for centuries all over the world to store water for irrigation, drinking water, and hydroelectric power. They are an important part of our infrastructure and can help reduce the impacts of floods and droughts. Dam failures can cause significant damage and loss of life, so we must take steps to ensure their safety. Students should learn about earthen dams and how to inspect them so they can be a part of keeping our communities safe.