Frame-type artificial reef measurement by side-scan sonar

To study the feasibility of assessing artificial reef construction quality by side-scan sonar, we conducted a field survey of a one-year-old stock protection artificial reef area using side-scan sonar technology in April, 2017. We selected two types of artificial reefs, AR1 and AR2, with 15 randomly selected reefs for each type. After software processing, the information of artificial reef height, settlement, structure and other data were obtained. The results show that the height of AR1 reef body was 3.74–4.76 m (average: 4.44 m), and the settlement rate was 13.52%–32.20% (average: 19.20%). The height of AR2 reef body was 2.57–3.45 m (average: 2.85 m), and the settlement rate was 13.67%–35.75% (average: 28.66%). By the time of investigation, two kinds of concrete reef structures were relatively complete, while individual reefs were dumped, and the actual reef layout had certain deviation from the preset layout. The results of single factor analysis of variance show that significant difference existed between the two types of reefs in anti-settling capacity, and AR1 had better reef-settling capacity than AR2.