Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 30178
The Effect of the Side-Weir Crest Height to Scour in Clay-Sand Mixed Sediments

Authors: F. Ayça Varol Saraçoğlu, Hayrullah Ağaçcıoğlu


Experimental studies to investigate the depth of the scour conducted at a side-weir intersection located at the 1800 curved flume which located Hydraulic Laboratory of Yıldız Technical University, Istanbul, Turkey. Side weirs were located at the middle of the straight part of the main channel. Three different lengths (25, 40 and 50 cm) and three different weir crest height (7, 10 and 12 cm) of the side weir placed on the side weir station. There is no scour when the material is only kaolin. Therefore, the cohesive bed was prepared by properly mixing clay material (kaolin) with 31% sand in all experiments. Following 24h consolidation time, in order to observe the effect of flow intensity on the scour depth, experiments were carried out for five different upstream Froude numbers in the range of 0.33-0.81. As a result of this study the relation between scour depth and upstream flow intensity as a function of time have been established. The longitudinal velocities decreased along the side weir; towards the downstream due to overflow over the side-weirs. At the beginning, the scour depth increases rapidly with time and then asymptotically approached constant values in all experiments for all side weir dimensions as in non-cohesive sediment. Thus, the scour depth reached equilibrium conditions. Time to equilibrium depends on the approach flow intensity and the dimensions of side weirs. For different heights of the weir crest, dimensionless scour depths increased with increasing upstream Froude number. Equilibrium scour depths which formed 7 cm side-weir crest height were obtained higher than that of the 12 cm side-weir crest height. This means when side-weir crest height increased equilibrium scour depths decreased. Although the upstream side of the scour hole is almost vertical, the downstream side of the hole is inclined.

Keywords: Clay-sand mixed sediments, scour, side weir.

Digital Object Identifier (DOI):

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1737


[1] Subramanya K, and Awasthy S. C. (1972). “Spatially varied flow over side-weirs”, J. of Hydrological Eng., ASCE 98(1): 1–10. W.-K. Chen, Linear Networks and Systems (Book style). Belmont, CA: Wadsworth, 1993, pp. 123–135.
[2] El-Khashab A. M. M., and Smith K. V. H. (1976) “Experimental investigation of flow over side weirs.” J. Hydr. Div., 102, 1255–1268.B. Smith, “An approach to graphs of linear forms (Unpublished work style),” unpublished.
[3] Uyumaz, A., and Muslu, Y., (1985) “Flow over side weir in circular channels.” J. Hydraul. Eng., 111, (1), 144–160.
[4] Ağaçcıoğlu H. and Yüksel Y. (1998) “Side-weir flow in curved channel”, Journal of Irrigation and Drainage Engineering, ASCE 124(3): 163–175.
[5] Uyumaz A, and Smith RH., (1991) “Design procedure for flow over side-weirs”, Journal of Irrigation and Drainage Engineering, ASCE 117(1): 79–90.
[6] Muslu Y., (2002) “Numerical analysis for lateral weir flow”, Journal of Irrigation and Drainage Engineering, ASCE 127(4): 246–253.
[7] Fares YR., (1995) “Boundary shear in curved channel with side overflow”, Journal of Hydraulic Engineering ASCE 121(1): 2–14.
[8] Fares YR., (2000) “Changes of bed topography in meandering rivers at a neck cutoff intersection”. Journal of Environmental Hydrology 8(13): 1– 18.
[9] Önen F. (2004) “Hareketli tabanli akarsularda yanal akimin hidrodinamiinin incelenmesi. (An investigation of hydrodynamic of lateral flows in movable bed rivers)”, PhD thesis, Yildiz Technical University, Istanbul, Turkey (in Turkish).
[10] Ağaçcıoğlu H, Önen F., (2005) “Clear-water scour at a side-weir intersection along the bend”, Journal of Irrigation and Drainage, ICID 54: 553–569.
[11] Ağaçcıoğlu H., Önen F. and Toprak Z. F., (2007) “Scour Around a Sıdeweır at a 300 section of a 1800 alluvial curved channel”, Jour. of Irri.and Dra. Eng., 56; 423-438.
[12] Rosier, B., (2007), “Interaction of Side Weir Overflow with Bed-Load Transport and Bed Morphology in a Channel”, PhD. Thesis, 421p., Karlsruhe Institute of Technology, Germany.
[13] Black, K. S., Tolhurst T. J. and Paterson D. M. (2002) “Working with natural cohesive sediments”, Journal of Hydraulic Engineering, 128(1): 2-8.
[14] Molinas, A., and Hosny, M., (1999) “Effects of Gradation and Cohesion on Bridge Scour, Volume 4, Experimental Study of Scour Around Circular Piers in Cohesive Soils”, Technical Report, Federal Highway Administration, U.S. Dep.of Transp. FHWA-RD-99-186.
[15] Hosny, M., (1995)“Experimental Study of Scour Around Circular Piers in Cohesive Soils”, Ph.D. Dissertation, Civil Eng. Dep., Colorado State Uni., Fort Collins, CO, 177 pp.
[16] Molinas, A., Hosny, M. and Jones, S. (1998) “Pier Scour in Montmorillonite Clay Soils”, Proc.of the 1998 International Water Res. Eng. Conf., ASCE, Vol. 1, pp 292-297.
[17] Molinas, A., Jones, S. and Hosny, M. (1999) “Effects of Cohesive Material Properties on Local Scour Around Piers”, Journal of the Transportation Research Board, Transportation Research Record, No. 1690, National Academy Press, pp. 164-175.
[18] Molinas A., (2003) “Brıdge scour ın nonunıform sedıment mıxtures and ın cohesıve materıals: Synthesıs Report”, Publication No. FHWA-RD- 03-083, Federal Highway Administration, U.S. Department of Transportation, Virginia.
[19] Ansari S.A., Kothyarı U.C. ve Ranga Raju K.G., (2002) ”Influence of cohesion on scour around bridge piers”, Journal of Hydraulıc Research, vol. 40, no. 6.
[20] Ansari S.A., Kothyarı U.C. ve Ranga Raju K.G., (2003)”Influence of cohesion on scour under Submerged Circular Vertical Jets”, Jour. of Hydr.c Eng., ASCE, 129 (12), 1014-1019.
[21] Debnath, K. and Chaudhuri, S., (2010)“Laboratory experiments on local scour around cylinder for clay and clay–sand mixed beds”, Eng.Geo., doi:10.1016/j.enggeo. 2009 .12 .003.
[22] Tan G., Jıang L. And Shu C.,(2010) “Experimental Study of Scour Rate in consolidated cohesive sediment”, Jour. of Hydrodynamics, 22 (1): 51- 57.
[23] De Marchi, G., (1934), “Saggio di Teoria de Funzionamente Degli Stramazzi Laterali, L’Energia Elettrica, Milano, 11:849-860.
[24] Del Giudice, G. ve Hager, W. H. (1999). Sewer Side Weir With Throttling Pipe, Journal of Irrigation and Drainage Engineering 125(5): 298–306
[25] Hager, W. H. and Volkart, P. U. (1986). Distribution channels, Journal of Hydraulic Engineering 112(10): 935–952.
[26] El-Khashab AMM.(1975) “Hydraulics of flow over side-weirs”, PhD thesis, University of Southampton, England.
[27] Neary, V. S., Sotiropoulos, F. and Odgaard, A. J. (1999), “Three dimensional numerical model of lateral intake inflows”, Journal of Hydraulic Engineering 125(2): 126–140.
[28] Neary V.S. and Odgaard A.J.(1993), “Three dimensional flow structure at open channel diversions”, Journal of Hydraulic Engineering 119 (11): 1223–1230.