Experimental results on scour at abutments under unsteady clear water flow condition are presented. Three shapes of short (abutment length/upstream depth < 1) were tested, namely, rectangular/vertical wall, semi-circular, and trapezoidal/45° wing-wall embedded in uniform sands two sizes having d50 = 0.52 mm 0.712 mm. The unsteadiness the is considered form flood hydrographs three forms, name...