Debris accumulations upstream and through crossing hydraulic structures like culverts causes to increase the upstream water level and the downstream scour depth which can leads to structure failure. This paper aims to investigate the effect of different inlet blockage ratio on culvert efficiency and scour hole depth. An experimental study was carried on. In non-blocked case, different submerged ratios (S=1.06, 1.33, 1.60, 1.90) were tested with different discharges. In blocked case, the effect of inlet blockage with different blockage ratios (Ar = 10%, 20%, 30%) was put on the pipe bed presented sediments blockage or on the upper part of culvert presented the floating debris. The results shows that as the submergence ratio increases, the maximum scour depth decreases at the same discharge and the relative energy loss is also decreasing in non-blocked case. In sediment blockage (Ar d) case, the relative maximum depth is increasing with increasing densimetric Froude number and with increasing blockage ratio. An empirical equation is developed to predict the relative scour depth under the present study conditions