Coasts as Natural Systems Flashcards
What type of system is a coastal environment
Open system
inputs in coastal environments
Energy from waves, wind, tides and sea currents
Sediment
Geology of coastline
Sea level change
Stores in the coastal environment from erosion processes
Erosional landforms and landscapes
What kind of environment is a coast
Dynamic environment where land meets sea
Stores in a coastal environment from wind and water transport
Depositional landforms and landscapes
What outputs are there in a coastal environment from wind and water transport
Dissipation of wave energy
Accumulation of sediment above tidal limit
Sediment removed beyond local sediment cells
What is an example of negative feedback in the coastal system
A beach is eroded, the cliffs behind it are exposed to wave attach. Sediment eroded from the cliffs is deposited on the beach , causing it to grow in size again. The negative feedback restores the balance of the system
What is an example of positive feedback in the coastal system
As a beach starts to form it slows down waves, which can cause more sediment to be deposited, increasing the size of the beach. The new equilibrium is reached when long term growth of the beach stops
Why is the coastal system in a state of dynamic equilibrium
If one of the elements of the system changes, e.g. there is increased deposition on a beach but there is no corresponding change in the amount of sediment removed from the beach, then the beach features may change and The equilibrium is upset
What does using a systems approach help to explain
Variations and changes that occur along a coastline
Helps to predict the possible consequences of natural processes or proposed human interventions, helps us plan for positive or negative impacts
How many sediment cells are there in England and Wales
11
What type of systems are sediment cells
Closed sediment systems
What happens if inputs exceed outputs
Then the beach will extend in height, length and/ or width = positive sediment budget
What happens if outputs exceed inputs
The beach with become smaller over time = negative sediment budget
What percentage of the world’s population live on coastal plains
Over 50% of population living within 150km of the sea
What is a sediment cell
A distinct area of coastline separated from other areas by well defined boundaries, e.g. headlands and stretches of deep water
What are the 4 different zones of a coastline
Backshore
Foreshore
Offshore
Nearshore
What is backshore
Area between the high water mark and the landward limit of marine activity. Changes normally take place here only during storm activity
What is foreshore
The area lying between the high water mark and the low water mark. Most important zone for marine processes in times that are not influenced by storm activity
What is offshore
Area beyond the point where waves cease to impact upon the seabed and in which activity is limited to deposition
What is nearshore
Area extending seaward form the high water mark to the area where waves begin to break.
What 3 zones are there in the nearshore zone
Swash zone
Surf zone
Breaker zone
What is the swash zone
Area where a turbulent layer of water washes up the beach following the breaking of a wave
What is the surf zone
Area between the point where waves break, forming a foamy, bubbly surface
What is the breaker zone
Area where waves approaching the coastline begin break usually where the water depth is 5 to 10m
Why might sediment cells lose sediment to outputs beyond the system even though it’s a closed system
If wave energy is very high or currents very strong, then sediment may be transferred to neighbouring cells, be lost to deeper sea areas offshore or be transferred to stores beyond the active coastal zone e.g. upper beaches
