Weirs and Locks

A weir is an artificial wall built across a river in order to make the river deeper. A weir is a small type of dam and it looks like a waterfall because water flows over the top of the weir.

A lock and weir system is needed where the river bed is steep and the water flows too quickly. Many rivers have locks so that ships can navigate rivers better. They are built to make a river more navigable. A lock system has been built at the Kazan Gorge along the Danube river. Ships can travel up and down the river because the river is deeper.

How locks work
The first lock gates open and the ship sails into the full lock. The first gates are closed and the water is slowly drained out of the lock until it reaches the same level as the river below the lock. The second lock gates are then opened and the ship sails on its way.

A lock on the River Thames	A lock on the River Medway

Boating
People who hire boats for boating holidays on rivers such as the River Thames near Goring in Oxfordshire have to go through locks to navigate the river. The lock may be built on one or both sides of the weir.