Estimation of effective usable and burial volumes of artificial reefs and the prediction of cost-effective management

In this study, effective usable and burial volumes were used to estimate the current state of nine cube-type artificial reefs (AR) constructed between 1987 and 2002. Three volume coefficients (k1, k2, and k3) were proposed for estimation of the total loss, effective usable volume, and burial volume of ARs, based on the recorded facility standard volume and seabed condition at the time of construction. Five parameters were redefined to clarify their use; two measures and three statistically obtainable coefficients were proposed from geometric hypotheses. Field data obtained from coastal waters near Busan in South Korea were used to demonstrate the estimation and prediction of these parameters. We determined that the burial volume of an AR can be predicted with less than 20% error using the mean values of k1 = 1.33, k2 = 1.36, and k3 = 1.37 for a rigid seabed and k1 = 1.32, k2 = 1.72, and k3 = 1.83 for a soft seabed. The effective usable volume can be predicted with less than 11% error using the mean values, seabed condition, and facility standard volume determined at the design stage. We found that it is unnecessary to use multi-beam echo, side scan sonar, and divers' investigation for prediction; hence, a cost-effective method was developed for the future management of ARs.