Difference between revisions of "Reach"
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(Created page with "=Reach= ==General description== ==Case studies where this River Characterisation is relevant== <Forecasterlink type="getProjectsForRt" code="5"/> ==Tools where this River C...") |
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− | == | + | == Definition == |
− | + | Section of river along which boundary conditions are sufficiently uniform that the river maintains a near consistent internal set of process-form interactions. (A river segment can contain one to several reaches). As a general rule, the length of a reach should not be smaller than 20 times the mean channel width, although shorter reaches can be defined where local circumstances are particularly complex. | |
− | + | == Delineation criteria == | |
− | == | + | * Channel morphology (particularly planform) |
+ | * Floodplain features | ||
+ | * Artificial discontinuities that affect longitudinal continuity (e.g. dams, major weirs / check dams that disrupt water and sediment transfer) | ||
+ | * River confinement | ||
+ | |||
+ | == Methods and data sources== | ||
+ | Segments are subdivided into reaches by visual interpretation of consistent river and floodplain (bio) geomorphic pattern using | ||
+ | * Google Earth | ||
+ | * Orthophotos | ||
+ | * Multi-spectral remotely-sensed data | ||
+ | * Lidar data | ||
+ | (Field reconnaissance can provide useful confirmation / additional data) | ||
+ | |||
+ | <gallery> | ||
+ | File:Frome_reach_deline.jpg|The River Frome is delineated into 15 reaches based on valley confinement, river planform and the presence of major weirs. | ||
+ | File:Frome_reach_type.jpg|The River Frome has sinuous, meandering and anabranching reaches. | ||
+ | </gallery> | ||
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[[Category:River Characterisation]] [[Category:Reach]] [[Category:Reach]] | [[Category:River Characterisation]] [[Category:Reach]] [[Category:Reach]] |
Latest revision as of 15:33, 7 January 2019
Reach
Definition
Section of river along which boundary conditions are sufficiently uniform that the river maintains a near consistent internal set of process-form interactions. (A river segment can contain one to several reaches). As a general rule, the length of a reach should not be smaller than 20 times the mean channel width, although shorter reaches can be defined where local circumstances are particularly complex.
Delineation criteria
- Channel morphology (particularly planform)
- Floodplain features
- Artificial discontinuities that affect longitudinal continuity (e.g. dams, major weirs / check dams that disrupt water and sediment transfer)
- River confinement
Methods and data sources
Segments are subdivided into reaches by visual interpretation of consistent river and floodplain (bio) geomorphic pattern using
- Google Earth
- Orthophotos
- Multi-spectral remotely-sensed data
- Lidar data
(Field reconnaissance can provide useful confirmation / additional data)