Sluice facts for kids

A sluice is like a special gate that controls the flow of water in a channel. Think of it as a movable barrier that can be opened or closed to let water through or hold it back. Sluices are often used to manage water levels in rivers and canals. They can also direct water to power things like watermills, or help in mining operations. You might hear them called "sluice gates," "knife gates," or "slide gates" – they all mean pretty much the same thing!

A sluice gate

How Sluice Gates Work

A sluice gate is a barrier, usually made of wood or metal, that slides up and down in special grooves along the sides of a waterway. When the gate is lifted, water flows underneath it. When it's lowered, it blocks the water.

These gates can be operated in different ways. Some are simple and opened by hand, perhaps with a chain or a crank. Others are much larger and use electricity or hydraulic power (which uses liquid pressure) to move them up and down.

Sluices in Logging

Long ago, in the mountains of the United States, sluices were used to move logs. These "logging sluices" were channels that helped transport cut trees from steep hillsides down to sawmills or storage areas.

Sometimes, during cold winter nights, water would be poured into these sluices. This water would freeze, creating a slippery layer of ice. The next morning, logs could slide down the icy sluice much more easily, reducing friction and making the work faster.

Sluices in Mining

Miners working a small sluice on Lucky Gulch, Alaska

Sluice boxes are very important tools in placer mining, which is a way of finding valuable minerals like gold or gemstones in sand and gravel deposits.

These sluice boxes can be small, used by people looking for minerals as a hobby, or very large for big mining companies. Inside a typical sluice box, there are small ridges called "riffles" and often a carpet-like material. As water washes the sand and gravel through the sluice, the heavier minerals (like gold) get trapped by the riffles and the carpet, while the lighter materials wash away. This process helps miners collect the valuable stuff!

Images for kids

• 

  The important parameters in designing sluice gates

• 

  A small wooden sluice in Magome, Japan, used to power a waterwheel

• 

  Sluice gates near Henley, on the River Thames

• 

  The Korenbrugsluice in Gorinchem is a fan sluice