Figure 1.1 shows a schematic plan view of a coastal area with most of the natural forcing conditions, natural features and some examples of man-made interventions in a natural coastal system. Most of the items are dealt with in these lecture notes.
The coastline in Fig. 1.1 receives sediment from rivers and is interrupted by openings called tidal or coastal inlets (see Intermezzo 9.2 for the terminology). The name tidal inlet refers to the fact that the tide is important in maintaining the inlet, viz. keeping the inlet from closing naturally. Tidal inlets are either found along barrier island coasts or along coasts interrupted by estuaries or lagoons. Tidal inlets and their associated basins are common features of lowland coasts all around the world.
Seen from the sea side, an estuary is an arm of the ocean that is thrust into the mouth and lower course of a river as far as the tide reaches. Estuaries receive fresh water from rivers, and salt water from the sea. Lagoons do not have a major point source of fresh water input, such as a river. These tidal systems play a crucial role in the sediment budget of the coastal zone and thus influence the long-term coastal evolution.
At the uninterrupted stretches of coast, waves are the dominant forcing agent. Wind waves and tides are treated in detail in Chs. 3 and 5 for oceanic and coastal waters respectively. The global variation in wave and tidal climate is discussed in Ch. 4.
Some examples of practical cases are given in this section by briefly discussing the following items from Fig. 1.1:
- Cross-shore profile (section A – A in Fig. 1.1);
- Morphological development in vicinity of a port;
- Delta near a river mouth;
- Tidal inlet;
- Dune erosion during a severe storm surge;
- Large artificial island in open sea.