Latest revision as of 16:33, 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)

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  The River Frome is delineated into 15 reaches based on valley confinement, river planform and the presence of major weirs.

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  The River Frome has sinuous, meandering and anabranching reaches.