Please enable JavaScript.
Coggle requires JavaScript to display documents.
WAVE AND SEA LEVELS - Coggle Diagram
WAVE AND SEA LEVELS
WAVE
-
CONSTRUCTIVE WAVE
Strong swash, weak backwash
Low wave height, long wavelength
Low frequency
Depositional
DESTUCTIVE WAVES
Strong backwash, weak swash
High wave height, short wavelength
High frequency
Erosional
VARIATIONS IN WAVES
In summer, constructive waves dominate but destructive waves dominate in winter.
Constructive waves may turn into destructive waves as a storm begins.
Climate change could mean that the UK may become more stormier meaning an increase in destructive waves.
Dams prevent sediment being transported from rivers and entering into the coastal area which means erosion could increase.
Interference with natural processes along the coast (e.g. through human activity) could affect sediment supply across a coastal area.
SEA LEVEL CHANGE
SHORT TERM
-
- Wind strength and direction - these can change causing a change in sea level for a couple of minutes or longer
- Atmospheric pressure - the lower the pressure, the higher the sea levels.
ISOSTATIC = LOCAL
Isostatic sea level change could be due to post-glacial adjustment (glaciers weigh down the land beneath, and so the land subsides until it melts). For example, post-glacial adjustment for the UK after the Ice Age has caused Southern England to subside around 1mm per year and Scotland to rebound and increase around 1.55mm per year.
TECTONIC ACTIVITY - EARTHQUAKES,VOLCANOS may cause land subsidence therefore causing isostatic sea level increase
EUSTATIC RISE = GLOBAL CHANGE
Eustatic rise is due to thermal expansion.
Water expands when it gets warmer, and so the volume of water increases which as a result, sea levels increase. This is due to Global Warming. However, predicting sea level change is very difficult because various factors could affect changes, and the cause isn’t still fully understood.
COASTLINE ENERGY
HIGH ENERGY COASTLINE
associated with more powerful waves, so occur in areas where there is a large fetch.
They typically have rocky headlands and landforms and fairly frequent destructive waves.
As a result these coastlines are often eroding as the rate of erosion exceeds the rate of deposition
LOW ENERGY COASTLINE
have less powerful waves and occur in sheltered areas
constructive waves prevail and as a result these are often fairly sandy areas
There are landforms of deposition as the rates of deposition exceed the rates of erosion.