People have been building dams for more than 5000 years.
The earliest dams were built to hold back water to be used for irrigation. This is where water is channelled into fields to help crops grow where the climate was sometimes dry.
They were also used to make it easier for boats to sail up and down rivers.
Nowadays, dams are built for all sorts of reasons. Irrigation as in ancient times, but also to create drinking water reservoirs, to generate hydroelectric power, to help control floods, to fill canals with water and still to help boats navigate rivers.
Dams can be built from different materials.
The smallest dams might be built of wood using wooden or metal posts and wooden boards. Larger dams might be built of earth, stone or concrete.
All modern dams have ways to take water out or let water pass using valves (like taps), bypass channels and spillways. These and the main dam have to be very carefully designed by civil engineers to avoid being damaged or washed away when the water behind the dam becomes too high due to heavy rain and flooding.
In Scotland and the rest of the United Kingdom, the safety of dams is protected by law and all dams over a certain size have to be inspected by specially trained civil engineers. In Scotland there are nearly 270 dams protected by this law.
The earliest of these dams in Scotland were built to store and channel water into the canals, but later ones were built to store drinking water or for hydroelectricity.
Did you have a go at building a dam like the beavers?
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