water smaller than a river. Streams are also sometimes called brooks. Streams may flow above or under ground, or even as a current in another body of water. Streams on land are often tributaries to rivers.
Streams may be classified in several ways:
- Relation to time.
- Perennial. One which flows continuously.
- Intermittent or seasonal. One which flows only at certain times of the year when it receives water from springs or from some surface source such as melting snow in mountainous areas.
- Ephemeral. One that flows only in direct response to precipitation, and whose channel is at all times above the water table.
- Relation to space.
- Continuous. One that does not have interruptions in space.
- Interrupted. One which contains alternating reaches, that are either perennial, intermittent, or ephemeral.
- Relation to ground water.
- Gaining. A stream or reach of a stream that receives water from the zone of saturation.
- Losing. A stream or reach of a stream that contributes water to the zone of saturation.
- Insulated. A stream or reach of a stream that neither contributes water to the zone of saturation nor receives water from it. It is separated from the zones of saturation by an impermeable bed.
- Perched. A perched stream is either a losing stream or an insulated stream that is separated from the underlying ground water by a zone of aeration.