Investigate the dominant Coastal processes acting on Porlock bay and also consider suitable management strategies for Porlock bay.

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Introduction

Aims:

* To investigate the dominant Coastal processes acting on Porlock bay.

* To consider suitable management strategies for Porlock bay.

This is an Investigation into the Coastal processes occurring in Porlock Bay, Exmoor National Park.

Porlock bay is a bay that has two points, which are Gore Point and Hurlstone Point. These two points were built because there was soft rock in between two hard rocks so it became a bay. This is a famous area for the tourists that go on holiday there because it is quiet and has beautiful natural scenery. It is also famous because of its geographical processes. This bay also has farmland growing on it.

Hurlstone point is at the West of Porlock Beach and is in the position of the end of Long Shore Drift. Therefore Hurlstone point had more rounded rocks. Hurlstone Point also has a cliff stopping the Long shore drift so that's why it might have more shingle on this point because the cliff (fig 1) acts as a natural barrier that blocks the rocks so they build up.

(A map of the 2 points is provided on the next page)

Gore Point is in the east of Porlock Beach and is in the position where LSD starts because the winds refracting and creating waves that hit at Gore point in a West direction. Because Attrition wouldn't be able to start its process, the rocks here are angular and sub-rounded. This place also has a groin that is man made.

These are pictures of the 2 points on the next page:

Photos of Hurlstone and Gore Point

Coastal processes involves a lot of things, like what influences Coastal processes like:

.Geology

Geology is the type of Earth you are investigating for example there is hard rock which is more resistant and soft rock which is more vulnerable to coastal erosions.

(Fig 2, 3, 4)

2.Wave Action

Wave Action is the type of wave that is hitting the coast. It could either be a destructive wave or a constructive wave which is:

* Destructive = When there is a weak Swash and a strong Backwash, removes material for the beach. These waves are only built up on rare occasions

* Constructive = When there is a strong Swash and a weak Backwash, Builds up beach material.

Swash is when the wave collapses into the beach and backwash is when the wave goes back into the sea. Swash carries lots of materials onto the beach such as rocks, sand or dirt building beach material while back swash is when the waves removes beach material as it goes back into the sea. (Fig 5)

This is basically long shore drift.

Long Shore Drift

Long shore is happening in porlock bay because the prevailing winds blows the waves towards england, the waves then hit the south west coast of England. These waves then refract and the waves then go towards Porlock bay where long shore drift occurs.

Longshore drift is the process by which the action of waves moves material along a beach or coastline. The direction of the waves is controlled by the 'FETCH' this is the distance or area that allows the wind to blow across the surface of the sea to create the waves.

The diagram below shows the effect of longshore drift on the direction of material movement. As you already know the wind does not come from the same direction all the time, but what does happen is that the wind tends to have a dominant direction which it blows in most of the time.

(Fig 6)

* (1) shows the direction of the Swash (this is the direction that the wave wash up the beach).

* (2) Shows the direction of the Backwash (this is the direction of the wave that washes down the beach).

* (3) demonstrates the overall direction of the movement of beach material)

Why is this important ?

Longshore drift supplies material to beaches along a coastline, making sure that the beaches are not eroded away by the action of the waves. It is possible to trap the material by the use of Groynes. These are 'arms' of wood that are built out to sea that trap the longshore drift to make the beaches wider.

The reason for doing this (widening the beach) is to force the waves to break on the beach and not at the base of the cliff which would cause the cliff to collapse and recide.

3.Sub-Aerial

Sub-aerial is when the whether acts on the coasts to speed-up or slowdown the rate of erosion. This process often ends up in slumping. Such as: (Fig 7, 8)
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4.Human Activity

Human activity is also known to speed-up or slow-down coastal erosions. A few examples are:

* Builing on top of cliffs

* Replenishment

* Groins

There also a few other protection strategies that I will explain later on in my investigation.

The Coast is eroded in a number of natural processes that slowly break up the coast.

These 6 processes are:

Coastal Erosion Processes

. Hydraulic Pressure: When Parcels of air trapped and compresses in joints in the rock. Pressure weakens rocks.

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