Estimation of Local Scour Depth around Submerged Spur-Dike Head

When a flow runs toward any submerged spur dike, due to the spur dike obstruction, a portion of the flow will move over the dike top to form a pressing circumferential flow, while the remained flow will move back toward the dike head to form another squeeze circumferential flow. Considering the flow around the submerged spur dike, a virtual boundary is invented respectively at the dike top and at the dike head to establish a mode of the pressing circumferential flow. Based on this mode, a formula of the local scour depth around the submerged spur dike head is established. The maximum squeeze width in the formula is determined by momentum equation and analysis of force acting on the circumfluence water. The adaptability of the formula is discussed in comparison between the calculated value and the data obtained in the modeling test in flumes as well as the data measured in the field. In such analysis the calculated value derived from the formula is generally consistent with the data measured in the field, which indicates that the formula properly describe the scour around the spur dike head.