1. School of Civil Engineering FACULTY OF ENGINEERING Lecture 14: Design Study 2 Millwood & Gaunless Flood Alleviation Schemes Dr Andrew Sleigh Dr Cath Noakes www.efm.leeds.ac.uk/CIVE/FluidsLevel1

2. 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

3. Gaunless Flood Alleviation Scheme Design Study 2

4. Gaunless Flood Alleviation Scheme Design Study 2

5. Gaunless Flood Alleviation Scheme Design Study 2

6. Gaunless Flood Alleviation Scheme Design Study 2

7. Gaunless Flood Alleviation Scheme Design Study 2

8. Gaunless Flood Alleviation Scheme Design Study 2

9. Gaunless Flood Alleviation Scheme Design Study 2

10. Gaunless Flood Alleviation Scheme Design Study 2 Question 1 Data Required Culvert Diameter 2.6 m Number of culverts2 Maximum culvert velocity1 m/s 1 in 200 year design flow48 m 3 /s 1 in 1000 year design flow242 m 3 /s

11. 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 = 48m 3 /s 4.Time = Volume / Q

12. 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 = 48m 3 /s 4.Time = Volume / Q 986 304 m 3 10.62 m 3 /s 37.38 m 3 /s 26386 seconds 7 hours 20mins

13. Gaunless Flood Alleviation Scheme Design Study 2 The Spillway

14. Gaunless Flood Alleviation Scheme Design Study 2 Limiting velocity down spill way Design for 1000 year flood gives 8m/s

15. Gaunless Flood Alleviation Scheme Design Study 2

16. Gaunless Flood Alleviation Scheme Design Study 2

17. Gaunless Flood Alleviation Scheme Design Study 2 Question 2 Data Spillway weir Cd0.73 Spillway weir width150 m 1 in 1000 year design flow242 m 3 /s Maximum velocity on spillway 8 m/s Assume velocity on spillway is 4 times the velocity over the weir

18. 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 = 242m 3 /s 4.Calc Velocity over weir 0.861 m 2.0 m/s 0.5 m 1.96 m/s

19. Gaunless Flood Alleviation Scheme Design Study 2 Diversion of culvert

20. Gaunless Flood Alleviation Scheme Design Study 2 Question 3 Data Water level above bend13m Flow velocity1 m/s Diameter2.6m Reduces to diameter1.5m Bend angle45 o Assume atmospheric pressure 10m water

21. Gaunless Flood Alleviation Scheme Design Study 2 Steps 1.Calc inlet pressure 2.Follow steps as in lecture examples 402 kN/m 2 225 130 N/m 2

22. 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