River is a general term for water flowing in a definite channel towards the sea, a lake, a desert basin, a main river, a marsh. The quantity and the level of water in a river depend on the sources feeding it and on their variation.
The rate of flow of water in a river depends on the mass of water, the gradient and the character of the channel which determines the specific features of flow. In rivers the flow of water is mostly turbulent (random and eddying), that is the rate of flow at each point of the stream is not constant either with regard to velocity or direction (pulsating).
Nile is the world's longest river (6650 km).
The mouths of rivers are the scene of complex interaction between the fresh river and the sea waters, where the transition from river to marine conditions takes place. Differences in the interaction of rivers and seas cause the formation of river mouths of different types. Two main types of river mouths are:
Abrasion: Form of erosion occurred by the rubbing of fine particles against an object.
Alluvium: Any material deposited by a river.
Bank: The ground at the side of a river.
Drainage basin: The area of land that is drained by a river and its tributaries.
Riverbed: The riverbed is the bottom of the water body.
Brackish: Water that is saline than river water but less saline than sea water
Channel: An area that encompasses flowing water narrowed by banks.
Delta: This is a triangular-shaped silty area at the mouth of a river at which the river divides into many various slow-flowing channels that have mud-covered banks.
Effluent: Wastewater that flows from a factory or other sources.
Estuary: The area where fresh water from the river meets salt water from the sea, where a river meets the ocean or sea.
Headwaters: Streams and rivers that are the sources of rivers or streams.
Hydrologic cycle: Another name for the water cycle.
Meander: Something that follows a zigzagging path.
Mouth: The mouth is the end of a river, where it drains into a large water body.
Oxbow lake: U-shaped water body that forms when a wide meander from the main stem of a river is cut off, making a separate water body.
Rill: A very small channel of water, produced mainly by runoff water that eroded the soil.
Riparian: Related to or Situated by the banks of a river, stream, or other water bodies.
Riverine: It means relating to, or formed by a river.
Runoff: It is water that drains into a river from uncontrolled tributaries, drains, etc.
Salinity: The amount of salt dissolved in water.
Sediment: It is small particles of soil or rocks that are carried by water or the wind.
Silt: Silt is very tiny particles of soil or rocks that are 3 to 60 micrometres in diameter.
Siltation: The deposit or accumulation of very minute soil particles.
Source: Beginning of a stream or river.
Tributary: A river or stream that flows into another stream, river, or lake.
Trunk: The main course of the river.
Watershed: The land that empties water into a specific river.