What is an Earthen Dam? Causes of Failure of Earthen Dam | Advantages & Disadvantages of Earthen Dam
What Is an Earthen Dam? Uses of of Earthen Dam | Causes of Failure of Earthen Dam
What Is an Earthen Dam?
An earthen dam is a structure made of soil and other natural materials. The primary purpose of an earthen dam is to regulate the flow of water by delaying the release of water from the dam or impounding water in the dam.
An earthen dam is a dam made from earthen materials, such as clay and sand. Earthen dams are usually cheaper and easier to construct than other types of dams, and they can be built as either temporary or permanent structures.
The most ancient types of embankments are earthen dams and earthen embankments, which are often constructed of locally accessible materials in their natural state with minimal modification.
Attempts at dam building date back to antiquity, but with the emergence of large-scale hydraulic engineering, networks of large dams are a common form of flood control and electrical power generation.
The dams which are constructed of earthen materials such as gravel sand, silt and clay are called as ‘Earthen Dam’.
They are ‘trapezoidal’ in shape. Earthen dams are relatively smaller in height and broad at the base.
Earthen dams are constructed where the foundation or the underlaying materials or rocks are weak to support the masonry dam or where the suitable competent rock is at greater depth.
History of Earthen Dams
Earthen dams are an old technology used for storing water for irrigation or for household use.
The earliest known dams are from the Mesopotamian region and were likely built using mud-bricks and reeds.
These dams were originally built to store water needed for irrigation. In the 19th century, the French government recognized the benefits of earthen dams and began to create their own.
The French learned that earthen dams were less expensive and easier to maintain.
An earthen dam, also known as low head dam, is a type of dam that is built from the earth and can be found in rural areas.
These dams are often used for livestock and agricultural purposes and can also be found in residential areas. An earthen dam is often used to help regulate water flow.
Earthen dams are relatively low cost and can help control water flow. Flooding is an issue that can be mitigated by using earthen dams.
Earthen dams can also help provide natural recreation areas, ponds and fish habitats. Earthen dams may not be the most aesthetically appealing but they are an effective way to divert water from one location to another.
Main Purpose of Earthen Dams
An earthen dam is a dam that uses natural material such as earth, sand, and gravel to create a barrier to hold back water.They are designed to store water and hold back the water to prevent it from flowing downstream.
The design process for earthen dams is kept as an open secret and its exact design methods are unknown. Earthen dams are sustainable, affordable, and environmentally friendly.
The content of the dam can be replenished as it is used up. Earthen dam construction can be designed and engineered for various purposes, such as:
- Flood control
- Flood prevention
- Drainage & Irigation
- Protecting against flooding
- Fish and wildlife management
- Providing water for livestock
- Power Generations
Causes of Failure of Earthen Dam
There are several causes of failure. They include;
- Rock movement in the embankment
- Slopes of the embankment failing to bear the weight
- A sudden increase in water level
- Water seepage along the sides of the embankment
- Lack of proper compaction in earthen dam
- Type and size of prepared material being used for dam construction and maintenance
- Dam site subsidence
- Overloads on dams due to floods or thawing of snow etc causing excessive failure
- Dam failure due to structural weaknesses
- Failure due to corrosion
- Dam failure can also be caused by combination of above causes.
Dam failures can be predicted using the method of controlling the strength of earthen dam and this is done by controlling the amount of material put in thereby allowing for expansion and contraction, so as to control the strength of earthen dam before after completion or during time period of construction.
Effects of Earthen Dam Failure
The most important effects of dam failure are listed below:
- Inundation-It is the start of flood resulting from earthen dam failure.
- Subsidence-It is the effect of dam failure on river bed resulting in loss of land, displacement of bridges, injury to road structures and other means of transportation etc.
- Flooding-This is the result of excessive release of water from earthen dam after its failure. It results in destruction of property and people can be washed away, if such water is not contained
- Drowning-This is the result of earthen dam failure. It could be due to dam failure resulting in loss of life either by earthen dams collapsing or by water overflowing and submerging roads, buildings, etc., if such water is not contained
- Sections-this is the result of earthen dam failure. It could be due to dam failure resulting in loss of life, damage or destruction of property if such water is not contained
- Landslide-This is the result of earthen dam failure. It could be due to dam failure resulting in loss of life, property or damage to infrastructure.
- Salination-It is the effect of earthen dams’ failure on the soil and water because of UV rays, and other factors.
- Deforestation-It is the effect of earthen dams’ failure on the soil and water because of excessive supply of water and vegetation clearing resulting in loss of soil from the river bed
- Irrigation-It is the result of earthen dams’ failure on the soil and water because of causing saltation under the soil leading to loss of agricultural crops and salt generation, thereby affecting irrigation schemes
- Flood control by Earthen Dams-It is the result of earthen dams’ failure. This process helps to reduce flood occurrence on the areas adjacent to river.
- Impact of Earthen Dam Failure on other natural resources-It is the result of earthen dams’ failure. This has a greater impact on fish population and aquatic life in area affected by earthen dam failure.
Rockfill Dams: The Advantages and Disadvantages of Rockfill Dams
The advantages of rock-fill dams are as follows:
- They are less expensive if suitable hard rock is available.
- They are appropriate where material for earth dams is not accessible.
- Advantageous when a concrete dam’s foundation is insufficient.
- Can be elevated later without much difficulty if necessary.
The Drawbacks of Rockfill Dams
- Building time is usually longer than that necessary for a concrete dam.
- More building equipment is required.
- Foundation requirements are stricter than for earthen dams.
- Expensive maintenance.
Embankment or Earthen Dam FAQs
1. What is an Earthen Dam?
- An earthen dam is a structure made of soil and other natural materials.
2.What are the advantages of Earthen Dams?
- They are easily constructed compared to concrete dams. They are cost effective and require less maintenance than concrete dams.
3. What are the Disadvantages of Earthen Dams?
- They could collapse during floods and earthquakes. They have limited design life, depending on the materials used to make them.
4. What is the difference between an Earthen Dam and a Rockfill Dam?
- An earthen dam is made of earth or sedimentary material, while a rockfill dam is made of fine-grained material such as sand, gravel or crushed stone.
5. What are the characteristics of an Earthen Embankment?
- The earth used to construct the embankment should be well compacted. The embankment must meet certain structural requirements for safety and stability.
- What is the minimum safety distance that has to be maintained between an Earthen Embankment and a Road?
- The minimum distance is 3 metres from the central line of a road. The road can be either cement concrete or tar macadam type of road, but it cannot be an earthen road.
7. What is a Geosynthetic Clay Liner?
- It is a prefabricated geotextile drainage and reinforcement material. It is used as an in situ liners of earthen dams.
8. What are the functions of a Geosynthetic Clay Liner?
- It reduces the seepage pressure of water through earthen dam wall. It acts as a drainage layer beneath the embankment. It prevents erosion of the embankment.