Hydrology: Attributes of a Healthy Stream
An alluvial stream is one whose channel is composed of the sediments transported by the stream itself and that generally changes the shape of its bed as the rate of flow changes. (Adapted from Attributes of an alluvial river and their relation to water policy and management by Trash, McBain, and Leopold).
Attribute Two: On Healthy Streams, Point Bars are Rearranged Periodically
Point bars are sand and gravel deposits that form at the inside of a bend or meander in a stream, opposite a pool.
The combination of point bar and pool repeats itself many times on a stream in one meander after another. Because of that, point bar and pool are said to form the fundamental building blocks of a healthy stream.
The development and rearrangement of point bars is important to the revitalization of riparian plant communities. Major floods are responsible for rearranging point bars, and when they do, they not only create diverse, high-quality riparian habitats, they also improve aquatic habitats for fish and aquatic insects. Periodic flood disturbances are essential to a properly functioning stream.
The animation at right depicts a large, infrequent flood event (say a 100-year flood), but smaller, frequent floods can also scour and rearrange point bars.
Click on the image to play this animation of a flood on the Jocko River to show how floods create and rearrange point bars.
Hydrology: Attributes of a Healthy Stream
An alluvial stream is one whose channel is composed of the sediments transported by the stream itself and that generally changes the shape of its bed as the rate of flow changes. (Adapted from Attributes of an alluvial river and their relation to water policy and management by Trash, McBain, and Leopold).
Attribute Two: On Healthy Streams, Point Bars are Rearranged Periodically
Point bars are sand and gravel deposits that form at the inside of a bend or meander in a stream, opposite a pool.
The combination of point bar and pool repeats itself many times on a stream in one meander after another. Because of that, point bar and pool are said to form the fundamental building blocks of a healthy stream.
The development and rearrangement of point bars is important to the revitalization of riparian plant communities. Major floods are responsible for rearranging point bars, and when they do, they not only create diverse, high-quality riparian habitats, they also improve aquatic habitats for fish and aquatic insects. Periodic flood disturbances are essential to a properly functioning stream.
The animation at right depicts a large, infrequent flood event (say a 100-year flood), but smaller, frequent floods can also scour and rearrange point bars.
Click on the image to play this animation of a flood on the Jocko River to show how floods create and rearrange point bars.
Hydrology: Attributes of a Healthy Stream
An alluvial stream is one whose channel is composed of the sediments transported by the stream itself and that generally changes the shape of its bed as the rate of flow changes. (Adapted from Attributes of an alluvial river and their relation to water policy and management by Trash, McBain, and Leopold).
Attribute Two: On Healthy Streams, Point Bars are Rearranged Periodically
Point bars are sand and gravel deposits that form at the inside of a bend or meander in a stream, opposite a pool.
Click on the image to play this animation of a flood on the Jocko River to show how floods create and rearrange point bars.
The combination of point bar and pool repeats itself many times on a stream in one meander after another. Because of that, point bar and pool are said to form the fundamental building blocks of a healthy stream.
The development and rearrangement of point bars is important to the revitalization of riparian plant communities. Major floods are responsible for rearranging point bars, and when they do, they not only create diverse, high-quality riparian habitats, they also improve aquatic habitats for fish and aquatic insects. Periodic flood disturbances are essential to a properly functioning stream.
The animation at right depicts a large, infrequent flood event (say a 100-year flood), but smaller, frequent floods can also scour and rearrange point bars.