Chapter Six Gravel Beaches and Barriers

Abstract

Publisher Summary Gravel beaches are a very important part of the world's coastline.Their morphodynamic behavior and the palaeoenvironmental implications of long-term changes in their morphodynamics are vital to coastal defense strategies, because these beaches protect many low-lying coastal zones from storm effects. In contrast to the wealth of research on hydrodynamics and sediment transport processes on sandy coasts, comparable studies on gravel beaches are few. The paucity of detailed process measurements on these beaches has been attributed to the difficulty of deploying sensitive equipment in energetic environments with mobile gravel-size clasts. Gravel beaches are, however, rather paradoxical in terms of mobility. The specific morphological features of gravel beach shorefaces, notably the lack or the poor development of a surf zone, imply a significant role by swash zone processes acting on the steep beachface, notably the control of swash asymmetry on beach gradients and in accretion or erosion phases. While swash processes are undoubtedly important in controlling the morphology of gravel beaches, the character of swash is dependent on the transformation of incident waves as they shoal, break, or surge and interact with the steep beachface.