3.1-Introduction To Coastal Systems And Landscapes Flashcards
-Coastal zones are dynamic environments with distinctive landscapes formed by the interaction of:
- A range of wind, marine and terrestrial processes
- as with all other natural systems, coasts have a range of inputs, stores, transfers/flows and outputs. These combine to create distinct landscapes. When inputs and outputs are in balance then the system is in a state of dynamic equilibrium. If one element in the gets without a corresponding change then the equilibrium is upset = feedback
About ___ of the world’s population live on coastal plains
50%
The coast is an example of an ____ system as it has inputs that originate from outside the system (such as sediment carried into the coastal zone by rivers) and outputs to other natural systems (such as eroded rock material transported offshore to the oceans).
Give an example
- open
- a small stream discharges water and inputs sediment into the sea at Selwicks Bay. The waves that affect this stretch of coastline are often driven by North Atlantic storms that pass into the Northern sea. Sediment eroded from cliffs is transported southwards, along the coast and deposited in parts of the Southern North Sea- an output from the system
As an open system, the coast has important links with other natural systems such as:
The atmosphere, tectonics, eco-systems, and oceanic systems; these natural systems are linked together by flows of energy and transfer of materials
A really clear example of the application of systems from concepts of the coast is
The sediment cells (closed coastal sub-system)
How many major sediment cells are there in England and Wales?
11
Give an example of sediment inputs, sediment transfers, stores or sediment and outputs of sediment
- input of sediment= from rivers and cliff erosion
- transfer of sediment= longshore drift
- store of sediment= beaches and spits
- outputs of sediment= transfers to the deep ocean
Give in chronological order, the template for a coastal system,
Check camera roll
Give some examples of inputs into the coastal system?
Energy from waves, wind, tides and sea currents
Sediment
Geology of coastline
Sea level change
Give some examples of outputs of a coastal system
Dissipation of wave energy
Accumulation of sediment above the tidal limit
Sediment removed beyond local sediment cells
Evaporation
Why use a systems approach?
Helps explain variations and changes that occur along a coastline- it also helps us to predict the possible consequences of natural processes or proposed human intervention; this can help us to forsee positive or negative impacts and plan for them
Coastal systems can be seen operating at
Various scales for example, an individual beach can be seen as a sediment store that has inputs and outputs
If inputs of sediment exceed outputs then the beach will
Extend in height, length and/or width resulting in a positive sediment budget
If outputs exceed inputs the beach will
Become smaller over time (a negative sediment budget)
If we consider a single beach within its larger sediment cell we can see that if the beach experiences a positive sediment budget, then somewhere else in the wider cell must be
Be experiencing a sediment loss for the overall balance to remain the same (and vice versa)
Although sediment cells are generally seen as closed systems, In reality there might be a slight loss of sediment to
Outputs beyond the system- e.g. if wave energy is very high or currents very strong, then sediment may be transferred to neighbouring cells, be ‘lost’ to to deeper sea areas off-shore or transferred to stores beyond the active coastal zone
When sediment is permanently lost to the system, the destinations are known as
Sediment sinks
A single beach consists of a series of different
Zones
The conditions in each zone of the beach depend upon a number of factors such as:
Tides
Wave action
Depth of the sea
What are the 4 major zones of a single beach?
- backshore
- foreshore
- nearshore
- offshore
Where is the backshore zone?
Area between high water mark and the limit of marine activity; changes only usually take place here during storms
Where is the foreshore zone?
Area between high water mark and the low water mark; it is the most important zone for marine processes
Where is the nearshore zone?
Area between the low water mark and the point where waves no longer have an effect on the land beneath them
Where is the offshore zone?
The area beyond the point where waves cease to impact upon the seabed. Activity is limited to the deposition of sediment
Give a negative feedback example in the coastal system?
Beach in dynamic equilibrium —> sediment is eroded from the beach during a storm —> sediment is deposited off-shore forming an offshore bar —> waves now forced to break before reaching the beach, dissipating their energy and reducing further erosion when they reach the beach
Give a positive feedback example in the coastal system?
Coastal management can inadvertently lead to an increase in erosion elsewhere along the coast- groynes trap sediment, depriving areas further down drift of beach replenishment and this can exacerbate erosion
Give a dynamic equilibrium example in the coastal system
Constructive waves build up a beach making it steeper; this encourages the formation of destructive waves that plunge rather than surge. Redistribution of sediment offshore by destructive waves reduces the beach gradient which, in turn, encourages the waves to become more constructive- this is a state of constant dynamic equilibrium between the type of wave and angle of the beach
There are links between the coastal system and
Other natural systems- coastal systems do not operate in isolation, they are inter-linked with other physical and human systems, both affecting and being affected by change
Give examples of physical and human systems both affecting and being affected by change
- during the Quaternary glacial and interglacial periods, sea levels fell and rose several times in response to changes in the global water cycle. The changing level of the sea affected the precise location of coastal processes at the edges of land masses; several landforms owe their development to changes in sea level.
- Recent changes in the global carbon cycle are indirectly affecting sea levels by causing global warming and this, in turn, is affecting coastal ecosystems; coastal regions suffering more severe flooding and being at greater risk from storm surges are clear impacts of these changes on human systems
- therefore it is evident to see how the world’s natural and human systems are inextricably linked together
