Segment characterisation

Segment

Aim

Characterisation of the process domains associated with fluvial processes at the segment scale and the physical pressures affecting them:

Characteristics and their quantification:

• Flow regime
• Valley characteristics
• Sediment size and delivery
• Riparian corridor features
• Physical pressures

Data layers and hydromorphologically relevant parameters

• River flow records assembled or modelled and ‘natural’ flow record assembled / estimated.
• DEMs analysed to estimate average valley slope and, for larger rivers, indication of river confinement within its valley.
• Analysis of aerial imagery, (where available) Lidar, and (for river bed sediment) existing morphological/habitat surveys to assess characteristics of the valley, riparian corridor and longitudinal physical pressures.

Potential data sources

• Flow gauging station records
• Digital elevation models [e.g. EU-GDEM)
• Google Earth images
• Multi-spectral remotely-sensed data
• Orthophotos
• Lidar data
• National surveys including: Physical habitat surveys, Riparian habitat surveys, Morphological surveys

Characteristics

Flow regime

Flow regime classification: (1) Assign to one of nine regime types; (2) Annual pattern of monthly flows

Flow characteristics: (1) Morphologically representative flows: median, 2yr or 10 yr frequency flood flows (Qpmedian; Qp2; Qp10.); (2) Extreme flows; (3) Abrupt anthropogenic flow: number, size, duration.

Valley characteristics

Valley characteristics: (1) gradient; (2) degree of valley confinement; (3) degree of river confinement.

Sediment

Sediment size: (1) dominant bed material calibre

Lateral sediment delivery: (1) eroded soil delivered to channel; (2) land surface instabilities connected to channel; (3) sediment delivery from bank erosion

Sediment load and budget: (1) estimated sediment transport; (2) segment gaining, losing or in-balance with respect to sediment transfer.

Riparian vegetation

Presence of a riparian corridor: (1) average width; (2) area; (3) proportion of valley bottom; (4) continuity

Riparian corridor vegetation coverage: (1) proportion trees, shrubs, short herbaceous, bare ground

Wood delivery potential: (1) proportion bank top under mature trees

Physical pressures

Longitudinal continuity: (1) channel blocking structures; (2) channel crossing / partial blocking structures

More details on the characterisation of segments can be found in chapter 5 of Deliverable 2.1.