1. WEIR MANAGEMENT AS STRUCTURAL MEASURES FOR FLOOD REDUCTION
TEAM
WEIR MANAGEMENT AS STRUCTURAL MEASURES FOR FLOOD REDUCTION 1

2. Contents
I. Introduction What is weir? Weir formulas? II. Approaches Research Based Approach Modelling Based Approach III. Conclusion

3. Introduction
Weir -
Small overflow-type dam generally used to increase the level of a river or stream.

4. Weir Formula (for Mike 11)
I. Villemonte (Villemonte, 1947) formula for sharp crested weirs

5. Weir Formula II. Honma formula (we use this)
III. Extended Honma formula

6. Weir Formulas (for ISIS)
Dry Mode
Q = 0
Free Flow (we use this for ISIS)
Drowned Flow
Round Nosed Broad Crested Weir (free flow)

7. Research Based Approach
1st Solution – Cut Off the Crest
High Overflow

8. Research Based Approach
2nd Solution – Adding Geotextile
High Overflow 8

9. Research Based Approach
3rd Solution – Automated Gate 9

10. Modelling approach Define objectives
Reduce downstream flooding
Find optimal heights for sediment equilibrium
Calibrate MIKE11 against observed levels
Build same model in ISIS
Compare results using ‘multi-model approach’

11. Multi-model approach
Model is the sum of the experience of the person who wrote the code

12. Reduce downstream flooding
No changes

13. Reduce downstream flooding
Downstream weir removed

14. Reduce downstream flooding
Four downstream weirs removed (1, 4, 5, 6)

15. Reduce downstream flooding
Weirs removed and manning’s reduced

16. Sediment transport qs related to q, s0, d50 Meyer-Peter formula
steady-state model
Mean flow depth
Mean channel width
Mean velocity
Channel Slope
Particle diameter d50

17. Sediment transport Results qs (kg/sec/m) Qs (kg/sec) Weir No. 1.6 34016
0.54
144 10 9 8
0.56 47 7
0.3
32.4 6 5
2.7
274 4
0.012
2.6 1

18. Conclusions MIKE11 results more sensitive to weir removal
Cannot conclude on effectiveness of weir removal due to model disagreement
Reduction of channel roughness better
Proposals:
Vegetation clearance downstream
Alteration of weirs to improve sediment regime

19. Sean and Ahmed who persistently work on Mike 11 and ISIS
Kim - our hydrological analysis expert

20. Alex – Partially involved to Mike 11 and Hydrological Analysis.
Our report maker.
Stephane – our GIS expert

21. Fazlul is working on Mike 11 and ISIS
Prima and Rajmund are working on Mike SHE report

22. Amandine – our hydrological analysist & web designer

23. Acknowledgment
Prof. Dr.-Ing. habil Klaus-Peter Holz as team 5 supervisor and his patience for assisting us during Hydroeurope 2010

24. References
Wikipedia (2010). Weir. Wikipedia Foundation, Inc.
White, Frank (2006). Fluid Mechanics. Mcgraw-Hill Education
Villemonte, James R Submerged-Weir Discharge Studies, Engineering News Engineering News Record, pp Record, pp

25. Thank you for listening