Date post: | 09-Feb-2017 |
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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
2
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
7
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
9
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
10
26 mei 2016
Study reaches
� Two study reaches of about 50 km:
� Braiding
� Meandering
12
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
25
� 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