{"references": ["Johnson P. A., and Dock D. A., Probabilistic bridge scour estimates, Journal of Hydraulic Engineering, 1996; 124 (7), 750\u2013754.", "F. Ahmed, N. Rajaratnam, Flow around bridge piers, Journal of Hydraulic Engineering, 1998; 124 (3), 288\u2013300.", "Kumar V., Ranga Raju K.G., and Vittal N., Reduction of local scour around bridge piers using slot and collar. Journal of Hydraulic Engineering, ASCE, 1999; 125 (12), 1302-1305.", "Melville B.W., local Scour at Bridge Sites, Rep. No. 117, Univ. of Auckland, Auckland, New Zealand (1975).", "Zarrati A. M., Nazariha M., and Mashahir M. B., Reduction of local scour in the vicinity of bridge pier groups using collars and riprap. Journal of Hydraulic Engineering, ASCE, 2006; 132 (2), 154\u2013162.", "Melville B. W., and Coleman S. E., Bridge scour. Water Resources Publications, LLC, Colorado, U.S.A., 2000; pp. 550.", "Fotherby, L., and Jones J., The influence of exposed footings on pier scour depths. Proceedings of the Hydraulics Conference, ASCE, New York, 1993; pp. 922\u2013927.", "Whitehouse R. J. S., Scour at marine structures: A manual for practical applications. Thomas Telford publications, Thomas Telford Ltd, 1 Heron Quay, London, United Kingdom, 1998; pp. 198.", "Zarrati A. R., Gholami H., and Mashahir M. B., Application of collar to control scouring around rectangular bridge piers. Journal of Hydraulic Research, 2004; 42 (1), 97\u2013103.\n[10]\tMashair M. B., and Zarrati A. R., Effect of collar on time development of scouring around rectangular bridge piers. 5th International Conference on Hydroscience and Engineering, Warsaw, Poland, 2002; pp. 9.\n[11]\tEntesar A.S. EL-Ghorab., Reduction of scour around bridge piers using a modified method for vortex reduction, Alexandria Engineering Journal, 2013; 52, 467-478.\n[12]\tDey S., Sumer B. M., Freds\u00d8e J., Control of scour at vertical circular piles under waves and current. Journal of Hydraulic Engineering, ASCE, 2006; 132 (3), 270\u2013279.\n[13]\tIZADINIA E., and Manouchehr H., Simultaneous use of cable and collar to prevent local scouring around bridge pier, International Journal of Sediment Research, 2012; 27, 394-401.\n[14]\tAbdel-Motaleb, M.M., Minimizing of scour around bridge piers using a new method for vortex reduction, Ain Shams Engineering Journal, 1997; 32 (2), 115\u2013125.\n[15]\tGarde. R.J. and U.C. Kothyari., ''Scour around Bridge Piers'' PINSA 64, A (4), 1998; pp. 569\u2013580.\n[16]\tZarrati A.R., Chamani, M.R., Shafaie A., Latifi M., Scour countermeasures for cylindrical piers using riprap and combination of collar and riprap. Int. J. Sediment Res., 2010; 25, 313\u2013 322.\n[17]\tChabert J., and Engeldinger P., Etude des affouillements autour des piles des ponts, (scour around bridge piers). Laboratoire National d'Hydraulique, Chatou, France (1956).\n[18]\tMelville B. W., and Chiew Y. M., Time Scale for Local Scour at Bridge Piers, Journal of Hydraulic Engineering, ASCE, 1999; 125 (1), 125-136.\n[19]\tRaudkivi A.J., Functional trends of local scour at bridge piers. Journal of the Hydraulics Division, ASCE, 1986; 112 (1), 1-13.\n[20]\tGraf W.H., Fluvial Hydraulics. John Wiley & Sons, N .Y (1996).\n[21]\tMia M.F., and Nago, H., Design method of time-dependent local scour at a circular bridge pier. Journal of Hydraulic Engineering, 2003; 129 (6), 420\u2013427."]}

Bridge piers often fail all over the world and the whole structure may be endangered due to scouring phenomena. Scouring has been linked to catastrophic failures that lead into the loss of human lives. Various techniques have been employed to extenuate the scouring process in order to assist the bridge designs. Pier modifications plays vital role to control scouring at the vicinity of the pier. This experimental study aims at monitoring the effectiveness of pier modification and temporal development of scour depth around a bridge pier by providing a collar, a cable or openings under the same flow conditions. Provision of a collar around the octagonal pier reduced more scour depth than that for other two configurations. Providing a collar around the octagonal pier found to be the best in reducing scour. The scour depth in front of pier was found to be 19.5% less than that at the octagonal pier without any modifications. Similarly, the scour depth around the octagonal pier having provision of a cable was less than that at pier with provision of openings. The scour depth around an octagonal pier was also compared with a plain circular pier and found to be 9.1% less.