Development of an empirical equation that predicts local scour around a single cube-type artificial reef under a steady current

Scour prediction around artificial reefs (ARs) remains difficult because it depends on several factors including particle size, flow velocity, and water depth. In this study, three-dimensional numerical simulations, laboratory experiments, and multi-linear regression analysis were conducted to define the equilibrium scour depth around a single cube-type AR under a steady current. The simulation results for local scour around a cube-type AR were in excellent agreement with the laboratory results. A dimensionless empirical equation that considered the flow velocity, water depth, and median particle size was developed to predict the equilibrium scour depth. The equation was high accurate; the correlation coefficient (R2) between the calculated and observed results was 0.93. Approximately 90.48% of 23 cases tested exhibited relative differences +/- 20% between the observed and predicted values. The equilibrium scour depth increased with increasing flow velocity, and decreased with increasing median particle size and water depth. The results will guide AR design and the implementation of measures that protect against scouring.