Effect of Vegetated Floodplain on Abutment Scour in Compound Channels

آب و خاک

Article 4, Volume 28, Issue 3, July 2014, Pages 503-512   

Document Type: Research Article

DOI: 10.22067/jsw.v0i0.26239

Authors

Y. Ramezani^{* 1}; M. Ghomeshi²; H. Khozeyme Nejad¹

¹University of Birjand

²Shahid Chamran University of Ahvaz,

Abstract

Bridge failures due to scour at bridge abutments clarify importance of scour prediction and scour countermeasures. Most of bridge abutments are located in floodplains. One of common cases in floodplains is the existence of vegetation cover. Scope of this study is investigation on effect of vegetated floodplain on vertical wall abutment scour in compound channels. Results show, for constant abutment length and flow depth, with increasing the vegetation concentration, scour depth decreased with an increasing rate. For constant vegetation concentration and abutment length, with increasing the flow depth, effect of vegetation in reduction of scour depth decreased. In abutment with the lengh of 26 cm and concentration with s=8, with increasing the flow depth from 4.8 to 11.8 cm, percentage reduction in scour depth decreased from 40 to 22 percent. Also, vegetation reduces scour hole dimensions and has effect on downstream topography.

Keywords

Bridge Abutment; Scour Hole; Clear Water; vegetation; Electromagnetic velocimeter

References

1- Ahmed F. and Rajaratnam N. 2000. Observations on flow around an abutment. Journal of Engineering Mechanics, 125(1): 51-59.

2- Barbhuiya A.K. and Dey S. 2003. Vortex flow field in a scour hole around abutments. International Journal of Sediment Research, 18(4): 310-325.

3- Dey S. and Barbhuiya A.K. 2005a. Flow field at a vertical-wall abutment. Journal of Hydraulic Engineering, 131(12): 1126-1135.

4- Dey S. and Barbhuiya A.K. 2005b. Turbulent flow field in a scour hole at a semicircular abutment. Canadian Journal of Civil Engineering, 32(1): 213-232.

5- Dey S. and Barbhuiya A.K. 2005c. Time variation of scour at abutments. Journal of Hydraulic Engineering, 131(1): 11-23.

6- Dey S. and Barbhuiya A.K. 2006a. 3D flow field in a scour hole at a wing-wall abutment. Journal of Hydraulic Research, 44(1): 33-50.

7- Dey S. and Barbhuiya A.K. 2006b. Velocity and turbulence in a scour hole at a vertical-wall abutment. Journal of Flow Measurement and Instrumentation, 17(1): 13-21.

8- FHWA Report. 2004. Enhanced abutment scour studies for compound channels. Publication No. FHWA-RD-99-156.

9- Gill M.A. 1972. Erosion of sand beds around spur dikes. Journal of the Hydraulics Division, 98: 1587-1602.

10- Kandasamy J.K. 1989. Abutment scour. Report No. 458. School of Engineering, University of Auckland, New Zealand.

11- Kwan F. 1984. Study of abutment scour. Report No. 328, School of Engineering, University of Auckland, New Zealand.

12- Kwan F. 1988. Study of abutment scour. Report No. 451, School of Engineering, University of Auckland, New Zealand.

13- Melville B.W. 1992. Local scour at bridge abutments. Journal of Hydraulic Engineering, 118(4): 615-631.

14- Stone B.M. and Shen H.T. 2002. Hydraulic resistance of flow in channels with cylindrical roughness. Journal of Hydraulic Engineering, 128(5): 500-506.

15- Sturm T.W. 1999. Abutment scour in compound channels. Stream Stability and Scour at Highway Bridges, ASCE, Reston, VA, 398. 443-456.

16- Tey C.B. 1984. Local scour at bridge abutments. Report No. 329. School of Engineering, University of Auckland, New Zealand.

17- Wong W.H. 1982. Scour at bridge abutments. Report No. 275. School of Engineering, University of Auckland, New Zealand.

18- Yang K.J., Cao S.Y. and Knight D.W. 2007. Flow patterns in compound channels with vegetated floodplains. Journal of Hydraulic Engineering, 133(2): 148-159.