False, a mature river is usually wide and slow moving
False
A mature river is on a shallower slope and it doesn't have rapids or waterfalls.(Waterfalls: steep fall of water, as of a stream, from a height.Rapids: part of a river where the current is swift.)
A mature river is on a shallower slope and it doesn't have rapids or waterfalls.(Waterfalls: steep fall of water, as of a stream, from a height.Rapids: part of a river where the current is swift.)
Rapids
cataract
V-shaped valleys typically include rapids and waterfalls. These valleys are formed by fast-flowing rivers eroding downwards into the landscape, resulting in steep sides and features like rapids and waterfalls due to the force of the moving water.
You could say καταρράκτες [=waterfalls]
Waterfalls or river rapids
A lock is the mechanism for raising and lowering ships in a river that has rapids or waterfalls. Locks are used to make navigation an easier task.
Portage.
CAtaract
A mechanism for raising or lowering ships in a river that has rapids or waterfalls is called dam and lock system. It is a special kind of dam system.