lecture 14: design study 2 millwood & gaunless flood alleviation schemes
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School of Civil EngineeringFACULTY OF ENGINEERING
Lecture 14: Design Study 2Millwood & Gaunless Flood Alleviation Schemes
Dr Andrew SleighDr Cath Noakes
www.efm.leeds.ac.uk/CIVE/FluidsLevel1
Gaunless Flood Alleviation Scheme
Design Study 2
• Gather data
• Sketch layout marking levels Marking areas where volume calcs required
• Draw a cross section Identify levels in each region
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Question 1 Data Required
• Culvert Diameter 2.6 m
• Number of culverts 2
• Maximum culvert velocity1 m/s
• 1 in 200 year design flow 48 m3/s
• 1 in 1000 year design flow 242 m3/s
Gaunless Flood Alleviation Scheme
Design Study 2
Steps
1. Calc volume in rise from 123 to 127 m
2. Calc flow in culverts (Q=Av) i.e. Flow out of the reservoir
3. Calc net inflow, Q = Qin – Qout Qin = 48m3/s
4. Time = Volume / Q
Gaunless Flood Alleviation Scheme
Design Study 2
Steps
1. Calc volume in rise from 127 to 127 m
2. Calc flow in culverts (Q=Av) i.e. Flow out of the reservoir
3. Calc net inflow, Q = Qin – Qout Qin = 48m3/s
4. Time = Volume / Q
986 304 m3
10.62 m3/s
37.38 m3/s26386 seconds7 hours 20mins
Gaunless Flood Alleviation Scheme
Design Study 2
The Spillway
Gaunless Flood Alleviation Scheme
Design Study 2
Limiting velocity down spill way
• Design for 1000 year flood gives 8m/s
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Gaunless Flood Alleviation Scheme
Design Study 2
Question 2 Data
• Spillway weir Cd 0.73
• Spillway weir width 150 m
• 1 in 1000 year design flow 242 m3/s
• Maximum velocity on spillway 8 m/s
• Assume velocity on spillway is 4 times the velocity over the weir
2/3actual 2
3
2HgBCQ d
Gaunless Flood Alleviation Scheme
Design Study 2
Steps
1. Calc allowable velocity over weir
2. Calc height Use Q = Av = BHv
3. Calc height for a 1000 year flood Q = 242m3/s
4. Calc Velocity over weir
0.861 m
2.0 m/s
0.5 m
1.96 m/s
Gaunless Flood Alleviation Scheme
Design Study 2
Diversion of culvert
Gaunless Flood Alleviation Scheme
Design Study 2
Question 3 Data
• Water level above bend 13m
• Flow velocity 1 m/s
• Diameter 2.6m
• Reduces to diameter 1.5m
• Bend angle 45o
• Assume atmospheric pressure 10m water
Gaunless Flood Alleviation Scheme
Design Study 2
Steps
1. Calc inlet pressure
2. Follow steps as in lecture examples
402 kN/m2
inletinletinlet
rrr z
g
u
g
pz
g
u
g
p
22
22
gg
uzz
g
pp inlet
inletrr
inlet
2
2
225 130 N/m2
22
Today’s lecture:
• Design Study
• Used basic fluid mechanics seen in lectures
• Sized and checked design
• For more info: www.efm.leeds.ac.uk/CIVE/FluidLevel1/CaseStudies
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