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Coasts as a natural system (Workbook 1) (System (Durdle Door (Dorset,…
Coasts as a natural system
(Workbook 1)
System
Input: wind, waves, tides, currents
Output: eroded or weathered material
Flows/Transfers: erosion, weathering, transportation, deposition
Stores/Components: landforms e.g beaches, dunes and spits
Dynamic equilibrium= inputs and outputs are balanced
Coast is constantly changing so it isn't steady
Tides, seasons, sea levels
Negative feedback= one change creates opposite changes to restore the balance
Positive feedback= one change creates similar changes which creates a new equilibrium
Durdle Door
Dorset, Jurassic Coast, Arch
INPUTS: sand, shingle, tide, waves, salt spray, prevailing winds, precipitation, incoming solar radiation
PROCESSES: run off, infiltration, deposition, mass movement
STORES: cliffs, headlands, bays, arches, beaches
OUTPUTS: sand, shingle, eroded material, weathered material
ATMOSPHERE: layer of gas surrounding the Earth consisting of Nitrogen, Oxygen, Argon, Carbon Dioxide. This controls the weather
HYDROSPHERE: layer of water near the surface that includes groundwater
LITHOSPHERE: crust and the upper mantle that is split into tectonic plates
BIOSPHERE: all living things (flora and fauna)
Chichester Harbour
West Sussex, open system
Cord grass at CH is causing positive feedback. The cord grass stabilises the mud and dissipates wave energy. Without it, the sediment gets eroded then carried away. It increases the tidal prism and fetch to increase erosion
Dynamic Equilibrium at a Coast
1) The coast is in equilibrium
2) There is a reduction in wave energy
3) It creates net onshore movement of sediment
4) Beach profile steepens
5) Backwash increases
6) There is less onshore movement
open system: inputs and outputs of material and energy are crossing the system boundary
closed system: elements cycle around within the system. material does not cross the boundary although energy may