Difference between revisions of "Reach"

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(Reaches)
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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.
 
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 ==
 
== Delineation criteria ==
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* Artificial discontinuities that affect longitudinal continuity (e.g. dams, major weirs / check dams that disrupt water and sediment transfer)
 
* Artificial discontinuities that affect longitudinal continuity (e.g. dams, major weirs / check dams that disrupt water and sediment transfer)
 
* River confinement
 
* River confinement
 
  
 
== Methods and data sources==
 
== Methods and data sources==
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* Lidar data
 
* Lidar data
 
(Field reconnaissance can provide useful confirmation / additional data)
 
(Field reconnaissance can provide useful confirmation / additional data)
 
  
 
<gallery>
 
<gallery>

Revision as of 15:32, 7 January 2019

Reaches

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)