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Channel Stabilization
With Submerged Vanes
Submerged Vanes
…work by generating secondary circulation in the flow
Submerged Vanes
Result:
River bed aggrades in one portion of the cross section and degrades in another
Submerged Vanes
Submerged Vanes
Submerged Vanes
Submerged Vanes
Applications
Vane Design Variables
Design Objectives
Design Objectives
Design Objectives
Design Solutions
Design Solutions
Tip vortex is described as a steady, potential Rankin vortex, and induced bed shear stresses calculated
Design Solutions
Sample solutions for river bends
Design Solutions
Sample solutions for straight river
Stabilization of Alignment
Channel was modified and bridge built in 1970
12 vanes were installed in 1984
Sections were surveyed in 1989
Stabilization of Alignment
1984 1989
Stabilization of Alignment
The vanes created an equilibrium-channel cross section with width increased just enough to respond to the increased slope
Problem was that owner had increased width too much
Cross sections measured August 22, 1989
Stabilization of Alignment
1989 Standing on bridge looking upstream
Stabilization of Alignment
1989 Looking downstream toward bridge
Stabilization of Alignment
1984 1989 2009
Stabilization of Alignment
2008 2010 2011
Stabilization of Alignment
Conclusion:
Channel has created new equilibrium cross section at bridge consistent with the new steeper slope
Stabilization of Alignment
Kaoping River, Taiwan
Stabilization of Banks
Stabilization of Banks
1988 1989
1988
Stabilization of Banks
Stabilization of Banks
1988 2008
Stabilization of Banks
Stabilization of Banks
Stabilization of Banks
Stabilization of Banks
Stabilization of Banks
Stabilization of River Segment
…at water intake on the Nile River, Egypt
Context:
Development of solution to sedimentation problem at intake, and
Preempt sedimentation and water shortage at proposed future units
Stabilization of River Segment
Challenges:
Design sediment management system such that channel characteristics are consistent with those of a stable river channel
Preserve and enhance channel stability
Stabilization of River Segment
Stability analysis shows:
River channel is ‘meandering’
Original plan form was stable
Original island was inherent part of stable channel plan form
Meander curve 2.6 km long
Power plant on inside of curve, naturally subject to shallow flow and sedimentation
Stabilization of River Segment
Small island was re-oriented in mid-nineties
Improved flow initially.
But …
Caused cross-over to move upstream
Caused upstream sand bar to grow bigger
Necessitated increased dredging
Stabilization of River Segment
Re-oriented island
Stabilization of River Segments
Stabilization of River Segment
Rock embankment (knoll)
Stabilization of River Segment
Stabilization of River Segment
Merits and effectiveness of proposed measures tested by simulations using ..
Numerical model of 9 km long reach
Hydraulic scale movable-bed model
Hydraulic scale model of existing intake
Stabilization of River Segment
Solution:
Two upstream flow deflectors
Sediment barrier
Submerged vane system
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Sunsari Morang Headworks Project on Kosi River, Nepal
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
Stabilization of River Segment
…on Waikato River, New Zealand
Stabilization of Rivers
• Submerged vanes …– Are a successful method for stabilizing a river
alignment, and for protecting a river bank against erosion
– Can help re-establish vegetation and habitat on and around the river, and help
– Facilitate sustainable developments in the vicinity
• For more information
• Questions?