How can scour threaten the stability of a quay wall?

Scour, which refers to the removal of seabed material by powerful water currents, poses a significant threat to the stability of a quay wall by undermining its structural support.12

For gravity walls, which rely on their own mass and the passive resistance of the ground in front of them to remain stable, scour can remove the essential soil providing that resistance. If the seabed material at the base of the wall is eroded, the wall may suffer from detrimental settlement or a loss of lateral stability, potentially leading to structural failure. To mitigate this risk, engineers must ensure that the foundations of such walls are carried a sufficient distance below the seabed level.1