bowston weir design discussion - scrt.co.uk
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Bowston Weir – Design discussion
CBEC ECO ENGINEERING11/4/2017
Bowston WeirWeir Attributes
• River Slope approximately = 0.01m/m
• Weir Height = 3m
• Backwater effect 0.7.𝐷
𝑠= 210𝑚
• Observed backwater = 300m
• Weir width approximately = 38m
Nearby Structures/ attributes
• House immediately downstream on the right bank
o Set back approximately 5 m
o 4.6m m above channel bed
• Road adjacent to RHB 330m U/S of weir
• Power lines upstream of weir
Model overview – Existing ConditionsMODEL NODES
Stage Summary
59.00
60.00
61.00
62.00
63.00
64.00
65.00
66.00
67.00
68.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00 900.00 1000.00
Sta
ge (
mA
OD
)
Realtive chainage (m)
Stage long profile
T2 - Maximum modelled water level (mAOD) T10 - Maximum modelled water level (mAOD)
T50 - Maximum modelled water level (mAOD) T100 - Maximum modelled water level (mAOD)
Velocity Summary
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00 900.00 1000.00
Velo
city (
ms
-1)
Relative chainage (m)
Velocity long profile
T2 - Average modelled velocity at peak flow (ms-1) T10 - Average modelled velocity at peak flow (ms-1)
T50 - Average modelled velocity at peak flow (ms-1) T100 - Average modelled velocity at peak flow (ms-1)
Shear Stress Summary
0.00
50.00
100.00
150.00
200.00
250.00
300.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00 900.00 1000.00
Shear
Str
ess (
nm
-2)
Axis Title
Shear Stress long profile
T2 - Shear Stress (nm-2) T2 - Shear Stress (nm-2) T2 - Shear Stress (nm-2) T2 - Shear Stress (nm-2)
Schematic of proposed design
Indicative design profile
Proposed bed regrading
and indicative location of
rock steps
Bowston Weir: Indicative schematic of bed regrading and rock
steps associated with “Full Removal” option
ReachLength between U/S and D/S hydraulic controls: 705mDrop in bed level: 3.99mChannel slope: 0.56%
Section to be regraded (vicinity of weir)Length: 310mDrop in bed level: 2.75Channel slope: 0.88%
Indicative visualisation
Concept visualisation: water levels and channel width to be adjusted following design stage