Self-burial of objects on sandy beds by scour: A synthesis of observations

Abstract

Factors that influence equilibrium, scour-induced burial depth (B) in sand relative to object diameter (D) are examined through analysis of over 750 observations. The main factors that increase scour-induced B/D under steady currents without waves are found to be an increased Shields parameter () and small D (< 3 cm), with separate power laws applicable to clear-water and live-bed conditions. For larger D, greater cylinder density also increases B/D under steady currents. The main factor that increases scour-induced B/D under wave-dominated conditions is an increased Keulegan-Carpenter number. B/D additionally increases as the mean current component parallel to wave orbitals decreases. For cylinders under waves, B/D also increases as increases and as the angle between wave orbitals and a cylinder’s axis increases. All else being equal, tapered cylinders bury most, followed by cylinders, then spheres, and conical frustums bury least. Parameterized models dependent on the above variables explain 85% of observed variance in B/D.