Safar Alyas Michael Al-Saffar, M. and Khalid Saddiq Al-Shaikh-Ali, D. 2008. Riprap Gradation Effect On Local Scour Around Bridge Piers. Al-Rafidain Engineering Journal (AREJ). 16, 1 (Feb. 2008), 56–68. DOI:https://doi.org/10.33899/rengj.2008.44049.