What is a Dam?

A dam is a big structure built across a river to retain its flow of water in a reservoir for several purposes, most commonly hydropower. Building a dam has many benefits such as electricity generation, water storage, flood control, recreation, and debris control.

Dams are usually built using concrete or natural minerals such as earth and rock.

For ages, dams have been a significant part of water infrastructure, serving numerous different purposes including:

  • Hydroelectric power: Reservoirs store rainwater to be used in hydroelectric power stations to generate electricity.
  • Water supply: Reservoirs store rainwater before it is filtered and processed for human use.
  • Flood control: Reservoirs control water flow into rivers after rainfall.
  • Irrigation: Water can be stored in reservoirs for irrigating land during dry spells.

Dam construction

Dam construction is often complicated and requires a wide array of professionals from different fields.

Normally it’s the civil engineers who have the responsibility for determining the best type of dam for the site, and for making technical drawings showing the construction process.

These civil engineers consult with engineering geologists and hydrologists on the technicalities of the site and the requisite specifications dependent on the amount of water involved.

Mechanical engineers will be contracted to design the required pipework, valves and floodgates.

Geotechnical engineers will ascertain whether the rock or soil below the proposed dam is strong enough to hold the weight and for determining probable permeability.

Generally, the usual process for dam construction is as follows:

River Diversion

Water flowing in a river is diverted to form a dry area in which to construct the dam.

Lower flows will be able to divert through channels built around the side of the dam area, excavated using explosives where required.

In the case of higher flows, it will be difficult for them to divert using separate channels. Therefore, a dry pit is formed on one side of the river, leaving the other side open for water to flow through. The dam is built in sections, with dry areas constructed in sequence. Openings are provided in the dam to let the river flow through.


The foundation is built below the original ground level, with weaker soils removed and replaced with stronger materials if required. To stop water leakage, cracks in the rock foundation must be filled with grout.  Then holes are drilled into the rock. Lastly, grout is pumped into the rocks so to fill the cracks.

Building the dam

Concrete dams need a huge quantity of ready concrete thus a concrete batching plant is usually constructed on site. Concrete is then transferred to the dam either using a system using trucks and cranes.

Why choose Jenyns & Jenyns?

Here at Jenyns & Jenyns, we have the best Dam Contractors.  With 40 years of successful work experience, we provide an exceptional level of workmanship at reasonable rates.

Our skilled team is equipped with the latest machinery to help them carry out their excavation task in the best possible way. If you want reliable Dam Contractors, just give us a call and we will take care of the rest.