Types of Dams

Types of Dams

Dams have existed for a long time. It is believed that, over 7,000 years ago, the Mesopotamians constructed dams to control the water level of the Tigris and Euphrates rivers. In 2900 BC, the first dam in recorded history was constructed, a masonry structure fifteen meters high over the Nile River at Kosheish. A National Geographic investigation estimates that there are 60,000 large dams across the globe. More than 3,700 more are under construction. Today, two of every three major rivers have been harnessed by dam construction. If smaller dams were included, the number would increase to over 600,000, worldwide.

Construction is only part of the plan. No matter the types of dams, dams must be maintained, assessed for damages, and repaired, or rehabilitated.

types of dams

The Purpose of Dams

ASDSO reports that dams are intended to provide water to all regions of North America. Dams maximize the use of water.

Dams are a crucial part of a country’s infrastructure. They are as important as highways, bridges, tunnels, bus stations, and airports.

Their functions include:

  • Domestic water supply
  • Agricultural irrigation
  • Industrial production
  • Flood control
  • Recreation
  • Hydroelectric power generation

Types of Dams

Nature creates dams when trees and other debris block a river. Beavers build natural dams. Humans construct dams to divert or harness the water.

Dams are classified according to the construction material being used. Other factors include the slope or cross-section of the dam. How the dam resists the force of water pressure is also a consideration.

Classification by Material

Dams have been built of timber, masonry, embankment materials, and other subtypes.

Timber dams were once widely used. They were quick and materials were readily available. They are rarely used anymore because they don’t last long. They also cannot be built very high. Timber dams must be kept wet to limit rot.

Constructed of compacted dirt or rocks, embankment dams rely on their weight to hold back the water.

Steel dams were an experiment of the early twentieth century. They used steel plating. They were deemed to be cheaper than concrete, earth, and masonry, and sturdier than timber.

Masonry dams are constructed of stone, concrete blocks, rubble, or brick.

Embankment dams are fabricated from natural materials or industrial waste. They are considered embankment dams if over half of their volume is compacted earth Hydraulic fill dams are constructed of dredged materials. Rock-fill dams use compacted or dumped rock, cobblestone, or quarried rock.

Classification by Purpose

Many times, dams are built to supply drinking water to towns and cities. Irrigation is another important purpose. In industry, dams create reservoirs to supply factories. They also contain and control effluent from industrial and mining by-products.

Some dams improve navigation and create recreation areas. They are used to prevent flooding. Dams can create a manmade habitat for fish and wildlife.

Dams make hydroelectric power generation possible.

Some dams serve several purposes.

Colorado dam construction

Classification According to Size

Low dams are lower than ten yards in height. Medium dams are larger than ten yards in height but under sixteen yards. Large dams are ones higher than sixteen yards. Major dams are over a hundred and eighty yards high.

Classification According to Type

There are many different classifications based on the types of dams. The purpose of a saddle dam, an auxiliary dam, or a dike is to allow higher water elevation and storage. Some saddle dams limit a reservoir and increase its efficiency. Saddle dams are placed in a low spot to prevent the inundation of nearby land. Dikes specifically reclaim arable land from a shallow body of water.

Levees are walls or embankments. They are situated along a body of water to protect the land from floods.

Overflow dams are constructed to be overtopped.

Weirs are small overflow dams used to measure water flow.

Check dams reduce the speed of the water flow and control soil erosion.

Wing dams, on the other hand, partially restrict the water. This creates a faster channel of water thus avoiding the buildup of sediment.

The purpose of dry dams is to control flooding by retaining water, allowing it to flow freely only when flooding occurs downstream.

USSD classifies dams according to type and purpose.

As the name suggests, diversionary dams change the course of a part or all of a river’s flow.

Gravity dams rely on their size or shape to retain water. If the site is chosen carefully, the mass of the gravity dam is a strong deterrent to floodwaters. Gravity dams may be solid or hollow. Grand Coulee Dam is a solid gravity dam. Itaipu Dam is a hollow gravity dam. Grande Dixence Dam in Switzerland is the world’s tallest gravity dam.

Arch dams get their stability from their arch shape and gravity action. The arch dam relies on firm supports at its abutments. Arch dams are best placed in a narrow canyon with steep, rocky sides. Arch bridges may be single arch, double arch, or multiple arched. The arch construction minimizes the amount of concrete required.

Buttress dams have a watertight part. They are supported at intervals on the downstream side by large buttresses made of reinforced concrete. Buttress dams may also have multiple arches.

Coffer dams are temporary structures to enclose a construction area. Diversion coffer dams divert a stream into a tunnel or channel.

Hydropower dams use different water levels between reservoirs and tailwaters to turn turbines, generating electricity.

Industrial waste dams create storage space for the disposal of industrial waste. The materials are suspended in water and moved to an embankment dam where they are incorporated with solid waste.

purpose of dams

Dam Maintenance

The United States Dam Safety Commission emphasizes that proper regular, thorough inspection and ongoing maintenance are crucial to dam safety.

Early detection of potential deficiencies and prevention of dam failure can avoid disasters and cut the cost of repairs. From the moment when a dam is constructed, inspection and maintenance need to be in place.

To ensure proper dam maintenance, it is vital to employ a reputable company that knows the inner workings of complex dam construction and has the skills to pinpoint and fix the most complicated, technical difficulties.

How Can Gracon Help?

Gracon’s dam maintenance division experts ensure that dams are correctly constructed and maintained, no matter the types of dams involved. Gracon specializes in the repair, replacement, and rehabilitation of mechanical equipment for dams of all sizes, materials, and types.

Gracon has a long successful history of reliable dam construction, maintenance, and repair. The professionals at Gracon specialize in installing and repairing radial, slide, crest, miter, and drum gates. Over the past ten years, the company has repaired over a hundred gates.

When it comes to knowledge, experience, and expertise, Gracon is a North American leader.

For more information on Gracon’s outstanding dam construction, maintenance, rehabilitation, and repair, contact us.