Results static & dynamic scenarios Background
Dynamic interactions between river morphology and vegetation affect river channel patterns and riparian species. Most models oversimplify either morphodynamics or vegetation processes. We developed a model coupling advanced morpho-dynamics and dynamic vegetation.
Objectives
• Understand and quantify the effect of dynamic vegetation development on the river pattern and morphodynamics of a meandering river.
• Investigate the long-term effect of a riparian invasive plant species on river morphology and native vegetation.
Static vegetation Dynamic vegetation
Results invader scenarios
Low density invader High density invader
Conclusions
• Dynamic vegetation creates and maintains dynamic meandering, creates nature-like vegetation patterns and age distribution
• River pattern and dynamics are sensitive to type, density and dynamics of vegetation
• Increasing vegetation cover decreases sediment transport, sinuosity, meander migration rate and bed level
• High density invaders reduces native vegetation cover, while lower density invaders increase native vegetation cover compared to the scenario without invaders
References
Van Oorschot et al. (2015). Distinct patterns of interaction between vegetation and morphodynamics. Earth Surface Processes and Landforms. DOI: 10.1002/esp.3864
Dynamic vegetation
Low density invader
High density invader Static vegetation
• Dynamic vegetation processes
• 2 vegetation types: Willows and Poplars
• No growth and mortality
• Colonisation each year in spring
• Dimensions based on Salicaceae shrub
• Japanese Knotweed introduction after 50 years in dynamic scenario
• Invader colonisation with low density (clonal spread)
Elevation (m)Width (m)
Length (m)
Width (m) Width (m)
Length (m)
• Japanese Knotweed introduction after 50 years in dynamic scenario
• Invader colonisation with high density (clonal spread + seed dispersal)
Time (y) Time (y) Time (y) Time (y)
Vegetation cover and age classes
A
B D
C
Emergence of different river dynamics through changing vegetation patterns
Mijke van Oorschot 1,2 *, Maarten Kleinhans 1 , Gertjan Geerling 2 , Hans Middelkoop 1
1 Faculty of Geosciences, Universiteit Utrecht, PO Box 80115, 3508 TC, Utrecht, the Netherlands.
2 Department of water quality & ecology, Deltares, PO Box 177, 2600 MH, Delft, the Netherlands. *mijke.vanoorschot@deltares.nl
Model runs inspired by the Allier river
Detrended bed level with vegetation
Length (m)
Detrended bed level with vegetation
Cross section with vegetation Cross section with vegetation
Comparing basic vegetation patterns, age distribution and age classes with aerial photos
Model verification
Old Young
Stripes
Dots
Areas
Young Old
Detrended bed level with vegetation
Length (m)
Detrended bed level with vegetation Japanese Knotweed (F. japonica)
Photo by B. Gruener
Morphodynamic statistics of the dynamic scenario (No invasion), low density invaders (LPP) and high density invaders (HPP)
Vegetation cover and age classes
This project was financially supported by REFORM (FP7 Grant Agreement 282656) and Deltares
Method
Bare
substrate
Colonisation
High water Low water
Mortality
Threshold
Slope
% Mortality
Pressure
Interaction
Hydraulic resistance using Chezy
Morphodynamic modeling with Delft3D and vegetation code by Van Oorschot et al. (2015)
