
In
hydrology
Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydro ...
, a stream pool is a stretch of a
river
A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...
or
stream
A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...
in which the water depth is above average and the water velocity is below average.
Formation

A stream pool may be bedded with
sediment
Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...
or
armoured with
gravel
Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone.
Gr ...
, and in some cases the pool formations may have been formed as basins in exposed
bedrock
In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...
formations.
Plunge pool
A plunge pool (or plunge basin or waterfall lake) is a deep depression in a stream bed at the base of a waterfall or Shut-in (river), shut-in. It is created by the erosion, erosional forces of cascading water on the rocks at the formation's bas ...
s, or plunge basins, are stream pools formed by the action of
waterfall
A waterfall is any point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge
of a tabular iceberg or ice shelf.
Waterfalls can be formed in seve ...
s. Pools are often formed on the outside of a bend in a meandering river.
Dynamics
The depth and lack of water velocity often leads to stratification in stream pools, especially in warmer regions. In warm arid regions of the Western United States, surface waters were found to be 3–9 °C higher than those at the bottom
Habitat
This portion of a stream often provides a specialized
aquatic ecosystem
An aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environ ...
habitat
In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
for
organism
An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...
s that have difficulty feeding or navigating in swifter reaches of the stream or in seasonally warmer water. Such pools can be important fish habitat, especially where many streams reach high summer temperatures and very low-flow dry season characteristics. In warm and arid regions, the stratification of stream pools provide cooler water for fish that prefer low water temperatures, such as the
redband trout (''Oncorhynchus mykiss'') in the
Western United States
The Western United States (also called the American West, the Western States, the Far West, the Western territories, and the West) is List of regions of the United States, census regions United States Census Bureau.
As American settlement i ...
.
Mosquito larvae, which prefer still and often
stagnant water, can be found in stream pools due to the low water velocity.
See also
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Pond
A pond is a small, still, land-based body of water formed by pooling inside a depression (geology), depression, either naturally or artificiality, artificially. A pond is smaller than a lake and there are no official criteria distinguishing ...
*
Reach (geography)
A reach is a segment of a stream, river, or arm of the sea, usually suggesting a straight, level, uninterrupted stretch.
They are traditionally defined by the capabilities of sailing boats, as a stretch of a watercourse which, because it is strai ...
*
Riffle
*
Stream gradient
Stream gradient (or stream slope) is the grade (or slope) of a stream. It is measured by the ratio of drop in elevation and horizontal distance. It is a dimensionless quantity, usually expressed in units of meters per kilometer (m/km) or feet pe ...
*
List of waterfalls by flow rate
*
List of waterfalls by type
Notes
External links
USGS: Stream Modeling website
{{DEFAULTSORT:Stream Pool
Water streams
Hydrology
Bodies of water