page_title: Lock (water navigation)
section_title: Use in river navigation
hierarchical_section_title: Lock (water navigation) / Use in river navigation
caption_attribution_description: Title: Lock Lines English: The lock between Chateau Laurier and Parliament Hill in Canada's capital city, Ottawa, Canada, situated on the Ottawa River.
context_page_description: A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is the chamber itself that rises and falls.
  Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. Later canals used more and larger locks to allow a more direct route to be taken.
  Since 2016, the largest lock worldwide is the Kieldrecht Lock in the Port of Antwerp, Belgium.
context_section_description: When a stretch of river is made navigable, a lock is sometimes required to bypass an obstruction such as a rapid, dam, or mill weir – because of the change in river level across the obstacle.
  In large scale river navigation improvements, weirs and locks are used together. A weir will increase the depth of a shallow stretch, and the required lock will either be built in a gap in the weir, or at the downstream end of an artificial cut which bypasses the weir and perhaps a shallow stretch of river below it. A river improved by these means is often called a Waterway or River Navigation (see example Calder and Hebble Navigation).
  Sometimes a river is made entirely non-tidal by constructing a sea lock directly into the estuary.
  In more advanced river navigations, more locks are required.
  Where a longer cut bypasses a circuitous stretch of river, the upstream end of the cut will often be protected by a flood lock.
  The longer the cut, the greater the difference in river level between start and end of the cut, so that a very long cut will need additional locks along its length. At this point, the cut is, in effect, a canal.
caption: Locks on the Rideau Canal, Entrance Valley, near Parliament Hill, Ottawa, Canada
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