3.1.3.1: Coasts as natural systems Flashcards
Define coast
The interface between land and sea
What type of system is a coast ?
Open
Give features of coasts as open systems
- Inputs originate from outside system (sediment carried into coastal zone by rivers)
- Outputs can go to other natural systems (eroded rock material transported offshore to ocean)
-Matter can move within system
Which other natural systems can coasts link to ?
- Atmosphere
- Tectonics
- Ecosystems
How does the flow of energy and transfer of material link natural systems in terms of a chalk cliff ?
Carbonation of chalk cliffs is vital in the carbon cycle to transfer carbon from the atmosphere to the hydrosphere which can help regulate earth’s climate. Dissolves salts are carried into deep ocean where they can be sequestered into new limestone layers as part of ocean sink of be used by marine organisms to build CaCO3 shells
What is used for the application of systems concept to coasts ?
The sediment cell
How many major sediment cells are there in England and Wales ?
11
What do sediment cells form the basis for ?
Coastal management
Define sediment cell
A conceptual way of describing movement from a source through transfer to a sink or output in a cyclical movement of sediment
What are inputs into a sediment cell ?
River and cliff erosion
What are outputs of a sediment cell ?
Transfer to the deep ocean
What are the transfers of sediment within a sediment cell ?
Longshore drift
Give criticisms of the sediment cell model
-Assumes a closed system whereas winds, tides and human activities often move sediment between cells as open systems
-Boundaries aren’t always clear and natural changes from erosion, sea level rise and human activities often impacts the shoreline
-Over simplification of human impacts on the sediment cell as shoreline management in 1 cell can often have knock on effects elsewhere
-Gives a static model for coasts whereas coasts are dynamic and becoming increasingly less predictable with climate change
Give an advantage of the sediment cell model
Encourages integrated coastal zone management by treating each cell as a single unit to understand the cause and effect of erosion and allow sustainable planning to account for transfers between cells
What are the main inputs into a coastal system ?
Precipitation and wind
What are the main outputs from a coastal system ?
Ocean currents, rip tides, sediment transfer and evaporation
What are the main forms of energy within a coastal system ?
Energy associated with flowing water, wind energy which is transferred to wave energy
What are the main stores/components within a coastal system ?
Beaches and sand dunes
What are the main flows and transfers within a coastal system ?
Wind blown sand, mass movement and longshore drift
Give an example of positive feedback within the coastal system
- Increased rate of erosion
- Groynes built to slow rate of erosion
- Groynes trap sediment and prevent areas downdrift having beach replenishment
- Exacerbated erosion
( although erosional rates downdrift are also influenced by wave energy and direction rock type and geology and human activity such as dredging and sea walls ( transfer high energy waves elsewhere down coast)
Give an example of negative feedback within the coastal system
- Rate of weathering and mass movement exceeds the rate of cliff foot erosion
- Screen slope forms
- Over time material extends up cliff face and protects it from subaerial processes
- Reduction in effectiveness of weathering and mass movement
Give an example of dynamic equillibrium within a coastal system
BETWEEN TYPE OF WAVE AND BEACH ANGLE
- Constructive waves build up a beach so it has a steeper gradient
- This encourages the formation of destructive waves which plunge into coastline
- This causes teh redistribution of sediment offshore which reduces the beach gradient
-This encourages the formation of more constructive waves again
How has the coast interacted with the water cycle natural system ? synoptic links
- During quarternary glacial and interglacial periods sea levels rose adn fell several times in response to changes in the water cycle which affected the precise location of coastal formation and processes e.g. landforms of submergence and emergence
-Rising sea levels (influenced by melting ice and thermal expansion can cause saltwater intrusion into freshwater coastal aquifers. This affects the hydrology of coastal zones and can damage ecosystems and water supplies.
-Coastal ecosystems like salt marshes and mangroves store and filter water .They help regulate local water cycles by slowing runoff, reducing flooding, and supporting evapotranspiration
-Warm ocean and coastal waters contribute to evaporation, which drives the atmospheric water cycle .This moisture can return as coastal rainfall, helping sustain coastal vegetation
How has the coast interacted with the carbon cycle natural system ? synoptic links
- Recent increases in atmospheric carbon causes global warming which is indirectly affecting sea levels and coastal systems. This ultimately affects human systems with increased risks of flooding and storm surges around the coast
