Coastal Environments and Global Change

7 Beaches

Gerben Ruessink¹ and Roshanka Ranasinghe²

¹Department of Physical Geography, Faculty of Geosciences, Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands ²Department of Water Science Engineering, UNESCO-IHE, Delft, The Netherlands

7.1 Introduction

7.1.1 Setting

Beaches can be defined as accumulations of sand or gravel found along marine, lacustrine and estuarine shorelines, and deposited by waves and wave-induced flows. Sandy beaches account for about 20% of the world’s coasts. Gravel beaches occupy approximately 10% of the global coastline and are found particularly in high-latitude areas. The beach constitutes the upper part of the shoreface (Fig. 7.1) and can be subdivided into three sub-systems:

Fig. 7.1 Typical cross-shore profile for: (a) a gently sloping sandy beach; and (b) a steep gravel beach, showing characteristic morphological features and hydrodynamical zones.

(Source: Adapted from Davidson-Arnott 2010. Reproduced with permission.)

1. Subtidal zone: This zone extends from the low-water mark to typical water depths of 5–10 m. It is here that waves incident from deep water shoal and break. The breaking-wave zone is also called the surf zone, and in its outer part the breaking waves ...