Floodplain vegetation modelling

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Floodplain vegetation modelling
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Participants

• Sara Puijalon
• Gregory Egger
• János Józsa
• Martin Baptist

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Sara

• PhD student, University of Lyon, Ecology of
  fluvial hydrosystems.
• Background in biology.
• Hydrodynamic aspects of abandoned channels with
  aquatic vegetation in Rhone River
• Effect of floodings on vegetation, considering
  plant morphology, survival mechanisms.

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Gregory

• Head of the Institute of Ecology and
  Environmental Planning in Klagenfurt, Austria
• Background in botany
• Modelling of vegetation, river basin planning and
  river restoration for alpine rivers
• Main interest in vegetation mapping, (spatially
  and temporally) and typology

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János

• Budapest University of Technology and Economics
• Associate professor at the department of
  hydraulic and water resources engineering
• Numerical modelling of river Tisza. Severe floods
  led to flood management measures flood
  conveyance, nature, agriculture. Roughness of
  vegetation.

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• Upper part of river Danube. Part is abanoned,
  average discharge is now too low. Floodplain,
  secondary branches protected landscape. Now on
  average too dry. Sometimes floods do occur. Then
  0.5 m siltation in places. Patchiness in
  vegetation, hydraulics and sedimentation.

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Martin

• Delft Hydraulics PhD at Delft University of
  Technology, Hydraulic engineering.
• Background in aquatic ecology
• Interaction between vegetation, flow, sediment
  transport and morphology.
• Cyclic Floodplain Rejuvenation
• Biogeomorphology

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Scales

• Many scales, from one plant to meandering rivers.
• Time scale for vegetation growth and succession
  from years to decades.
• Vegetation dynamics is affected by disturbances.

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Topic

• Predictive modelling of hydro-morphology and
  vegetation dynamics.
• effect of disturbances by floods
• intermittent dynamics of floods that affect the
  dynamics of floodplain vegetation
• Why to predict future conditions of the river
  with regard to river restoration.

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Disturbance concept for floodplain vegetation

• A disturbance will
• 1. modify habitat parameters (hydromorphology)
• 2. disrupt vegetation (biology)
• 1. leads to a different habitat and therefore
  changes vegetation type
• 2. leads to regression of vegetation

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Dynamic vegetation modeling
phytocoenosis
habitats
disturbance
time scale
erosion and
redepositon of
bedlow
phytocoenosis
phytocoenosis
Scrubs with Salix sp.
habitats
habitats
disturbance
disturbance
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Disruption of vegetation

• Little data on response of plants on flood events
  (lots on average conditions)
• Plants and trees may go down and half of the
  island erodes. Floodplain vegetation is
  protection against erosion.
• There is interaction between disruption of
  vegetation and hydromorphology

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Habitat parameters in river-floodplain-ecosystems
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Hydromorphological changes

• Difficult to make predictive model
• Lack of knowledge on effect of vegetation on
  sediment transport and morphology

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Group 1 Hydraulic forces on plants

• Sara, Martin and János
• Sara measures the drag force on a single plant in
  a laboratory.
• Martin measures vertical profiles of velocity and
  turbulence for a group of plants (400 m-2).
• Exchange data, ideas and students

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Group 2 Floodplain vegetation

• Franz Kerle, Gregory Egger, János Józsa and
  Martin Baptist
• Make model of disturbance effects on floodplain
  vegetation
• Based on data on the Lech and Danube Machland
  (Austria), Allier (France)