What is a stream?
In the upper course of a river, streams are small, straight and fast flowing with water falls and rapids. In the lower reaches, stream velocity is lower and sediments are deposited forming flood plains or alluvial plains.
A stream can be defined as short, usually continuous body of running water. Creek, stream and river are terms used for flowing water in a river basin, depending on the size. Creeks would be the smallest water bodies, streams would be in the middle, and rivers would be the largest of the three.
Streams flow downhill due to gravity and the topography defines the direction of flow, as they follow the path of least resistance, through cracks. Small streams, springs and run-off come together to form larger streams. Streams can be classified according to stream order:
- First order stream: a headwater channel with no tributaries.
- Second order stream: a stream formed below the confluence of two first-order channels. Third-order streams are created when two second-order channels join, and so on.
The intersection of a channel with another channel of lower order does not raise the order of the stream below the intersection. In general, streams in the upper course are first, second and third order streams; in the middle course, we find fourth, fifth and sixth order streams, and in the lower course we find sixth streams and beyond.