Marine and Coastal Environments

Abstract

The present coastline of western Europe is shaped by physical processes such as wind, waves, and tidal currents, which cause the marine and coastal sediment transport. Spatial gradients in sediment transport rates induce the morphological adaptation, reflected by either an accumulation or erosion of material. All mutual interactions between these physical processes, and the resultant gradients in sediment transport together with the morphological adaptations, constitute the coastal morphodynamics. The specific initial stage of the morphology and the availability of sediment influence the direction of the morphological adaptation, whereas the rate of the morphological adaptation mostly depends on the energy input into the system. Chemical processes are of less importance in coastal environments of the high to mid-latitudes. Here most geochemical reactions are far too slow to influence the coastal morphology. However, biological processes sometimes play an important role. For example, flocculation of fine sediments by algae in estuaries (Ten Brinke 1993) or filtering by salt-marsh vegetation (Houwing 2000a, b) both positively influence the sediment accumulation rates. The long-term boundary conditions upon which the physical processes act are often determined by geology. The nature of the drainage basin that delivers fresh water and sediments into coastal waters and the nature of the shoreline can be considered as static boundary conditions for short-term morphodynamics. Tectonic forces and global sea-level rise are typical long-term geophysical forces. They will slowly change these boundary conditions, but they hardly influence the short-term adaptations of the morphology. The western European shelf fringes a series of integrated coastal environments that vary from coastal dunes and sandy beaches to estuaries and tidal basins and to sea cliffs and shore platforms. In this chapter a general description of the location and dimensions of the shores of western Europe is presented, followed by a brief summary of its geological history. The geology is focused on present-day deposits, the local lithology with sinks and sources of sediments, and with reference to some geophysical processes such as the relative sea-level rise. Thereafter, the actual coastal processes are discussed.