Details are given herein of the bed level changes in vicinity of the oscillating flap by means of physical modelling. Experiments were performed in a wave flume with a movable bed. Based on the results, changing the flap rotation angle (α) from a constant to an oscillating state caused less bed level changes (reduced range and length). Increasing the h/L (h=water depth, L=wave length) decreases the range of bed level change profile and was effective on bed form. The H/h (H=wave height) only affects the range of bed level changes profile in such a way that increasing this parameter first raise and then decreases the bed level changes. Intraction of above three parameters (α,h/L and H/h) with the velocity components show that, by increasing the distance from the oscillating flap, more regular trend of velocity changes was observed. While complex behaviour was recognized in close distances to the structure.