WEIR MANAGEMENT AS STRUCTURAL MEASURES FOR FLOOD REDUCTION.
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WEIR MANAGEMENT AS STRUCTURAL MEASURES FOR FLOOD REDUCTION
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Transcript of WEIR MANAGEMENT AS STRUCTURAL MEASURES FOR FLOOD REDUCTION.
WEIR MANAGEMENT AS STRUCTURAL MEASURES
FOR FLOOD REDUCTION
Contents
I. Introduction
What is weir? Weir formulas?
II. Approaches
Research Based Approach
Modelling Based Approach
III. Conclusion
Weir -
Small overflow-type dam generally used to increase the level of a river or stream.
Introduction
Weir Formula (for Mike 11)
I. Villemonte (Villemonte, 1947) formula for sharp crested weirs
Weir FormulaII. Honma formula (we use this)
III. Extended Honma formula
Dry Mode
Round Nosed Broad Crested Weir (free flow)
Weir Formulas (for ISIS)
Free Flow (we use this for ISIS)
Q = 0
Drowned Flow
Research Based Approach
1st Solution – Cut Off the Crest
High Overflow
Research Based Approach
2nd Solution – Adding Geotextile
High Overflow
Research Based Approach
3rd Solution – Automated Gate
Modelling approach
Define objectives1. Reduce downstream flooding
2. Find optimal heights for sediment equilibrium Calibrate MIKE11 against observed levels Build same model in ISIS Compare results using ‘multi-model
approach’
Multi-model approach
Model is the sum of the experience of the person who wrote the code
Reduce downstream flooding
No changes
0
20
40
60
80
100
120
140
0 5000 10000 15000 20000 25000 30000
ISIS
measured
Bed Level
MIKE11
Reduce downstream flooding
Downstream weir removed
0
20
40
60
80
100
120
140
0 5000 10000 15000 20000 25000 30000
ISIS
measured
Bed Level
MIKE11
Reduce downstream flooding
Four downstream weirs removed (1, 4, 5, 6)
0
20
40
60
80
100
120
140
0 5000 10000 15000 20000 25000 30000
ISIS
measured
Bed Level
MIKE11
Reduce downstream flooding
Weirs removed and manning’s reduced
0
20
40
60
80
100
120
140
0 5000 10000 15000 20000 25000 30000
ISIS
measured
Bed Level
MIKE11
Sediment transport
Meyer-Peter formula
qs related to q, s0, d50
steady-state model • Mean flow depth
• Mean channel width
• Mean velocity
• Channel Slope
• Particle diameter d50
http://ponce.sdsu.edu/onlinemeyerpeter.php
Sediment transport
Results
qs (kg/sec/m) Qs (kg/sec) Weir No.
1.6 340 16
0.54 144 10
0 0 9
0 0 8
0.56 47 7
0.3 32.4 6
0 0 5
2.7 274 4
0.012 2.6 1
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:
1. Vegetation clearance downstream
2. Alteration of weirs to improve sediment regime
Sean and Ahmed who persistently work on Mike 11 and ISIS
Kim - our hydrological analysis expert
Alex – Partially involved to Mike 11 and Hydrological Analysis.
Our report maker.
Stephane – our GIS expert
Fazlul is working on Mike 11 and ISIS
Prima and Rajmund are working on Mike SHE report
Amandine – our hydrological analysist & web designer
Acknowledgment
Prof. Dr.-Ing. habil Klaus-Peter Holz as team 5 supervisor and his patience for assisting us during Hydroeurope 2010
References
Wikipedia (2010). Weir. Wikipedia Foundation, Inc. http://en.wikipedia.org/wiki/Weir
White, Frank (2006). Fluid Mechanics. Mcgraw-Hill Education
Villemonte, James R. 1947. Submerged-Weir Discharge Studies, Engineering News. 1943. Engineering News Record, pp. 118-120. Record, pp. 54-57
