An experiment to see if Longshore drift will occur in direction of the prevailing wind.

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Methodology

Day:                Tuesday

Date:                11th June

Time:                10.30 am – 6.00 pm

Weather:        The weather was fairly cold in the morning and eventually turned sunny.  However, later in the day it started drizzling.  It was also very windy.

A list of the equipment used:

  • Ranging poles
  • Spirit level
  • Metre Rulers
  • Quadrats
  • Cailleux Roundness Index

Five different groups were spread out at equidistant spacing along the beach.  Group A will be located to the east of the beach, closer to Durdle Door and Group E will be to the west, closer to Bats Head.  

Hypotheses:

Physical

  • Longshore drift will occur in direction of the prevailing wind.

The prevailing wind is the wind which blows most frequently in an area.  The prevailing wind along the south coast of England is generally SW.  The waves are influenced by the SW wind, and they travel in the same direction as the wind.  

The waves carry boulders pebbles, sand and shingle in strong weather.  As the wave reaches the water edge, they break because the friction increases.  The swash carries the material up the beach at the same angle as the waves.  The swash deposits heavy material close to the water’s edge as it begins to lose energy.  The backwash returns to the sea under the influence of gravity dragging some material with it.  Longshore drift occurs from the west to east in a south-westerly wind.  

  • The height of the beach should increase towards Durdle Door.

This is due to the material, which is being deposited close to Durdle Door as it acts as a groyne.  This is due to longshore drift as it occurs from west        east.

  • Pebbles decrease in size from west to east and become rounder as a result of longshore drift.

They decrease because when they move they are being eroded. Attrition is when pebbles bang against each other as they are being eroded and become rounder and smoother.  This is due to a process called transportation.  The waves carry material up and down the beach; the major movement is along the coast by a longshore drift.  

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  • Pebbles decrease in size with increasing distance from the shoreline to the cliff.

This is because big pebbles are being deposited before smaller pebbles due to the action of the waves.  There are two types of waves, constructive and destructive waves.  Constructive waves are when the swash has more energy than the backwash.  Destructive waves are when the backwash has more energy than the swash, therefore material is being destroyed.  The swash deposits heavy material close to the water’s edge as it loses energy.  The heavy material consists of bigger pebbles.  The backwash water returns to the sea under ...

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