Experimental study of scouring characteristic around hexagonal artificial reef

Artificial reef is a structure placed underwater which has similar function with natural reef. Artificial reef can also serve as a submerged breakwater. When placed in shallow water, the structure is vulnerable to scouring and soil subsidence which cause structural failure. This paper present serial testings in Ocean Environment and Ocean Energy Laboratory, Ocean Engineering Department, ITS, to determine the scouring characteristic with variation of gap, and waves for 1: 10 model scale hexagonal artificial reef. The results of this research can guide the planning of structural protection against scouring. From a series of tests, it can be summarized that for 1 diameter gap reef distance, the maximum scouring occurs behind the structure, whereas for no gap distance, it occurs at the front of the structure. At the center of the structure, for no gap distance, sedimentation occurs dominantly, whereas for 1 diameter gap distance, scouring process occurs dominantly. The maximum scouring depth (5,3cm) occurs when the gap is equal to 1 diameter of reefs and minimum scour(2,9 cm) occurs when there is no gap between the reef.