spring
The source of a river - is the point at which it emerges as a stream from the water that forms its origin. This is usually run-off from boggy ground, at a higher altitude than sea level.
river basin
in the Saint Lawrence River as it emerges from the northeast corner of Lake Ontario.
The course of the Brahmaputra River flows southwest via the Assam Valley, and south through Bangladesh, and emerges in the Ganges Delta , through the Meghna, and empties in the Bay of Bengal.
alluvial fan occurs when the gradient of a river bed decreases suddenly as when a river emerges from a mountain
A large stream of surface water is usually called a river. A river is freshwater and runs from high to low ground.
Irrigation!
This is called irrigation - specifically it is "surface irrigation".
Mountains / hills ; (River) divides.
A large stream of surface water is usually called a river. A river is freshwater and runs from high to low ground.
The low ground between two hills is called a valley.
The source of a river is usually a spring. Rain sinks into soil or rock layers, then flows downhill until a point where it emerges, which is called a spring. The water then flows downhill on the surface as a river. Some rivers, however, source from the melting ice and snow at the tops of very tall mountains.