impact of discharge on the channel pattern and dynamics of the yellow river
TRANSCRIPT
Impact of peak discharge increase
on the channel pattern and
dynamics of the Yellow River
Filip Schuurman
2 November 2016
26 mei 2016
The Yellow River (Huang He)
� 6th Longest river in the World (5500 km)
� Large social, economic and geographical value
� Dynamic river
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26 mei 2016
South-North Water Transfer project
� Sedimentation in the hydropower reservoirs
� Water shortage, despite water storage in hydropower
reservoirs
� Water transfer from wet Yangzte River basin to dry Yellow
River basin
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26 mei 2016
Research question:
How does the higher discharge affect the channel pattern and morphodynamics
in the Yellow River?
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26 mei 2016
Methods
� System analysis:� Field data� Satellite photography
� Computer simulations:� Hydrodynamics + sediment transport + morphology� Calibration + validation: 1999 - 2014� Prediction future: 2015 - 2040
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26 mei 2016
Settings
� Curvilinear, structured grid
� 2D depth-averaged
� Grid resolution sufficient to capture bars
� Annual hydrograph based on expected discharge
regulation scheme
� Sediment inflow equal to local transport capacity
� Fine sediment (0.11 mm)
� Engelund-Hansen
� Variable morphological factor
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26 mei 2016
Study reaches
� Two study reaches of about 50 km:
� Braiding
� Meandering
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Braiding reach Meandering reach
26 mei 2016
However…
� First results give static channels with only
morphodynamics in first years
�Dry-wet bank erosion mechanism is insufficient
� Similar to earlier studies
(e.g. Schuurman et al., 2013)
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26 mei 2016
Bank erosion in Delft3D
� Dry-wet bank erosion mechanism at maximum
� Boost of bank erosion by:
� Strong spiral flow (Espir = 2)
� Strong transverse bed slope effect (alpha = 0.2)
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26 mei 2016
Summary
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� Higher (peak) discharge had large effect on the river pattern:� Higher braiding intensity� Transformation from meandering to braiding� Severe sedimentation on the floodplains
� Without mitigation measures, the transfer of water from the Yangtze River to the Yellow River is expected to have large economic and social impacts
� Modelling of channel dynamics required a ‘trick’ for bank erosion, which worked well