Coastal Processes
Coastal processes refer to the natural forces and mechanisms that shape and change the coastline. These processes include erosion, transportation, and deposition of sediment by waves, tides, and currents. They play a crucial role in shaping coastal landforms and can have significant impacts on human activities and infrastructure in coastal areas.
4 Key excerpts on "Coastal Processes"
- Gerd Masselink, Michael Hughes, Jasper Knight(Authors)
- 2014(Publication Date)
- Routledge(Publisher)
...In this example, pre-existing conditions of sediment supply and sea-level tendency strongly controlled the response of the coastal system to forcing. This example also highlights the concept of equifinality, whereby the two barriers are morphologically similar but were formed at different times and under different conditions. Coastal sedimentary and morphological systems are an amalgam of elements of different ages and on different scales. As such, coastal landscapes can be described as a palimpsest, whereby sediments or landforms from one time period are variously preserved, overprinted or destroyed by later conditions or processes. The net result is a coastal system that has a multi-layered and partial history of environmental forcing and coastal response. The rest of this book explores the basis of these forcing factors and describes their impact on the processes and geomorphology of real coasts. SUMMARY • The spatial boundaries of the coastal zone correspond to the limits to which Coastal Processes have extended during the Quaternary period and include the coastal plain, the shoreface and continental shelf. • The coastal morphodynamic system consists of processes, sediment transport, morphology and stratigraphy. An essential ingredient to coastal morphodynamics is the feedback between morphology and processes. • The major environmental conditions affecting coasts are geology, sediment supply/characteristics and external energy sources (wind, waves and tides). Human activity is an emerging forcing factor on most coasts worldwide, and is perhaps the dominant factor on many. • There is a close coupling between temporal and spatial scales in coastal morphodynamics. Therefore, the modification of large-scale features occurs over long time periods, whereas small-scale features change over short time periods. • Coastal morphodynamic systems possess a number of fundamental characteristics that make prediction of coastal evolution difficult...
eBook - ePub- Tom Beer(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
...To the unobservant, the shoreline is a static environment that does not change from day to day. Nothing could be further from the truth. Shorelines as a whole (and, in particular, the beaches) are dynamic systems of continual change. The beaches themselves are composed of whatever material is locally in greatest abundance now or was abundant in past geological times. The principal sources of beach and nearshore sediments are as follows: rivers which bring large quantities of sand and mud directly to the coast; the unconsolidated material of sea cliffs, which are eroded by waves; and material of biological origin, such as shells, coral fragments, and skeletons of small marine organisms. Many beaches, such as those along the east coast of the U.S., are supplied by sand that has been reworked by waves and currents from ancient river and glacial material deposited during former times when the sea level was in a different position. The energy carried by waves provides the predominant natural tool by which the shore’s continual sculpture is wrought. Waves can transport large amounts of energy, and the continual dissipation of this energy can, with time, wear away the toughest of stone. This is erosion. Yet, at different locations, waves can transport sand and build up beaches. This is accretion. In recent years urbanisation has produced a far greater threat via crowding shorelines than natural wave action. In many parts of the world, beaches have been lost through lax building standards allowing real estate development on fragile sand dunes. FIGURE 2.1 Beach profile illustrating terminology. Natural processes continue to occur, even if human activities have disrupted them. Development must work with, and understand, the forces shaping the shoreline. Most important of all is the behaviour of waves and their interaction with the shallow bottom and the shore in the nearshore wave zone...
eBook - ePub- Simon Bell(Author)
- 2012(Publication Date)
- Routledge(Publisher)
...Introduction The previous chapter showed how climate, particularly the aftereffects of the last (but probably not the final) glaciations, has driven and continues to drive many changes occurring in the landscape. The landform patterns and processes which are the subject of this chapter are no exception to this, and in fact in them we can see both the results of climatic processes and their continuing role in modifying climatic processes in the short to medium term, such as volcanic eruptions throwing gas and dust into the atmosphere. The structure and processes of geology supply the basic underlying layer or substrate upon which all terrestrial life and human activities rely. Geology interacts directly with climate to maintain a continuously dynamic state. However, the rates of geological change are generally so slow that for most ecological processes, or considerations for human use, it supplies a relatively stable framework and sets limits or boundary conditions. Areas of ancient shield rocks, where erosion is extremely slow, possess extremely stable geologies. There are places in which dramatic processes occur reasonably frequently, notably in regions with active volcanoes and earthquakes, where processes can disturb and modify ecological or cultural patterns quite dramatically, and occasionally disastrously for anyone living there. It is not the purpose of this chapter to provide a primer on geology, geomorphology or hydrology; instead it is to interpret what we perceive in this field in terms of the patterns and processes, insofar as they help us to read the landscape and to give us a basis for understanding the ecological and human patterns superimposed upon it...
eBook - ePubCoastal Engineering
Processes, Theory and Design Practice
- Dominic Reeve, Andrew Chadwick, Christopher Fleming(Authors)
- 2018(Publication Date)
- CRC Press(Publisher)
...Chapter 5 Coastal transport processes 5.1 Characteristics of coastal sediments Sediment transport governs or influences many situations that are of importance to mankind. In rivers and estuaries and on coastlines, sediment movements can result in significant erosion or accretion over both local areas and much wider geographic areas. This can take place on time scales of a few hours (resulting from storms or floods) to months and years (as a result of the seasonality in the waves and currents) to decades and beyond (as a result of changing climate and natural and manmade influences). Important manmade facilities can have their operation impaired or destroyed by sediment deposition, for example, by reducing the capacity of reservoirs, interfering with port and harbour operations and closing or modifying the path of watercourses. Erosion or scour may undermine structures on or in watercourses and coastlines. Thus, the study of sediment transport is evidently of significant importance. As previously mentioned in Chapter 1, most of our beaches today are composed of the remnants of sediments washed down the rivers in the last Ice Age, predominantly sands and gravels. Traditionally the sand and gravel sizes have been classified according to the Wentworth scale. This defines sand as being very fine (0.0625 mm to 0.037 mm), fine (0.037 mm to 0.25 mm), medium (0.25 mm to 0.5 mm), coarse (0.5 mm to 1 mm) and very coarse (1 mm to 2 mm). Material sizes larger than this are classified as gravel, subdivided into granular (2 mm to 4 mm), pebble (4 mm to 64 mm), cobble (64 mm to 256 mm) and boulder (> 256 mm). Rounded gravel, typical of a significant number of UK beaches, is referred to as shingle. There are several physical properties of sand and gravel beaches which are important in the study of coastal sediment transport. The first is the sediment density (ρ s), typically 2650 kg/m 3 for quartz...
