WEIR MANAGEMENT AS STRUCTURAL MEASURES FOR FLOOD REDUCTION TEAM 5 2010 WEIR MANAGEMENT AS STRUCTURAL MEASURES FOR FLOOD REDUCTION 1

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

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

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

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

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

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

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

Research Based Approach 3rd Solution – Automated Gate 9

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’

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

Reduce downstream flooding No changes

Reduce downstream flooding Downstream weir removed

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

Reduce downstream flooding Weirs removed and manning’s reduced

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 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 9 8 0.56 47 7 0.3 32.4 6 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: Vegetation clearance downstream 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

Thank you for listening