Coasts
, Coast as a System
SYSTEM - set of interrelated objects compromising components (stores) SEDIMENT CELLS
and processes (links) that are connected to form a working unit - Stretch of coastline associated nearshore area within which
movement of sediment, sand and shingle is self contained
COASTS IS AN OPEN SYSTEM - energy and matter can be transferred
from neighbouring systems - CLOSED system but not fully due to wind, tidal currents
- 11 large sediment cells around E & W coast
Inputs = outputs ] equilibrium - Boundaries determined by topography and shape of
Dynamic equilibrium- equilibrium disturbed and self regulation to coastline
restore equilibrium - Large physical structures; Lands End - natural barriers
E.g. which prevent transfer of sediment to adjacent cells
Large storm
Increase wind speed
(KE) generates larger
waves
Large waves remove
more sediment than
replaced by LSD
Increased rate of erosion
, Factors affecting Coasts
WINDS TIDES
- Source of energy for coastal erosion +sediment transport - Periodic rise and fall of sea surface and produced by
= wave transportation gravitational pull of moon (and lesser extent) the sun
- Wave energy generated from frictional drag of winds - Moon pulls water towards it = high tide = compensatory
moving across ocean surface (fetch) bulge on opposite side of earth
- Higher wind speed = larger fetch - Between 2 bulges = low tide
- Onshore winds are effective at driving waves towards
coast
- Winds blow at oblique angle = towards coast and
resultant waves also approach obliquely = LSD
- Wind carries erosion, transportation and deposition
- Wind = movement from high to low pressure
- Aeolian - process caused by wind action
- Fetch - distance of open water in one direction from a
coastline, over which the wind can blow
1. Sun creates thermal energy
2. Warms part of the earth so hot air rises
3. Low and high pressure form and air moves between
these as wind
4. Wind blowing over oceans as KE creates waves
5. Waves possess potential energy and kinetic energy (due
to motion of water within wave) TIDAL RANGE: influences where wave action occurs and
6. As wave breaks, PE transferred to KE which moves up weathering
beach as swash Enclosed seas (Mediterranean) = low tidal ranges = restrictive wave
7. KE runs out = swash stops travelling up action due to narrow land area
8. Gravitational potential energy causes backwash Funnelled coast (Severn Estuary) = high tidal range (14m)
, Coast as a System
SYSTEM - set of interrelated objects compromising components (stores) SEDIMENT CELLS
and processes (links) that are connected to form a working unit - Stretch of coastline associated nearshore area within which
movement of sediment, sand and shingle is self contained
COASTS IS AN OPEN SYSTEM - energy and matter can be transferred
from neighbouring systems - CLOSED system but not fully due to wind, tidal currents
- 11 large sediment cells around E & W coast
Inputs = outputs ] equilibrium - Boundaries determined by topography and shape of
Dynamic equilibrium- equilibrium disturbed and self regulation to coastline
restore equilibrium - Large physical structures; Lands End - natural barriers
E.g. which prevent transfer of sediment to adjacent cells
Large storm
Increase wind speed
(KE) generates larger
waves
Large waves remove
more sediment than
replaced by LSD
Increased rate of erosion
, Factors affecting Coasts
WINDS TIDES
- Source of energy for coastal erosion +sediment transport - Periodic rise and fall of sea surface and produced by
= wave transportation gravitational pull of moon (and lesser extent) the sun
- Wave energy generated from frictional drag of winds - Moon pulls water towards it = high tide = compensatory
moving across ocean surface (fetch) bulge on opposite side of earth
- Higher wind speed = larger fetch - Between 2 bulges = low tide
- Onshore winds are effective at driving waves towards
coast
- Winds blow at oblique angle = towards coast and
resultant waves also approach obliquely = LSD
- Wind carries erosion, transportation and deposition
- Wind = movement from high to low pressure
- Aeolian - process caused by wind action
- Fetch - distance of open water in one direction from a
coastline, over which the wind can blow
1. Sun creates thermal energy
2. Warms part of the earth so hot air rises
3. Low and high pressure form and air moves between
these as wind
4. Wind blowing over oceans as KE creates waves
5. Waves possess potential energy and kinetic energy (due
to motion of water within wave) TIDAL RANGE: influences where wave action occurs and
6. As wave breaks, PE transferred to KE which moves up weathering
beach as swash Enclosed seas (Mediterranean) = low tidal ranges = restrictive wave
7. KE runs out = swash stops travelling up action due to narrow land area
8. Gravitational potential energy causes backwash Funnelled coast (Severn Estuary) = high tidal range (14m)
