Previous research has shown that 60% of bridge collapses are caused primarily by the floods and scours process, which weakens the lateral strength of bridges. Open channel flume experiments were conducted to determine the erosion rate of sediments. Nine sediments were tested for erosion rate measurement by placing sediments in the hole of the wooden plank placed in the flume. The critical erosion rate was determined corresponding to 0.1 mm/hr. Additional research was conducted to investigate further the relationship between the critical state friction angle of the soil and the slope of local scour holes. In conclusion, an empirical relationship is derived between the mean size of sediments, critical state friction angle, and specific gravity to identify their impact on critical mean flow velocity and critical shear stress. The Shields diagram was utilized to calculate the Shields critical number, and the relationship between the Shields critical number and the critical state friction angle was derived. The proposed empirical equations were then evaluated using statistical error indices.