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

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