Segment

Segment

Definition

Section of river subject to similar valley-scale influences and energy conditions.

Delineation criteria

• Major changes in valley gradient
• Major tributary confluences (significantly increasing upstream catchment area, river discharge)
• Valley confinement (confined, partly-confined, unconfined)
• In mountainous areas, very large lateral sediment inputs

Methods and data sources

1. Major segments are identified by applying GIS tools to a DEM with river network overlay, to define downstream breaks in valley gradient (and width) and in upstream contributing area.
2. Major segments may be subdivided according to valley confinement interpreted from DEMs
3. Google Earth images
4. Orthophotos

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  The River Frome is delineated into 6 segments based primarily on major tributary confluences.