Transcript Coastal Erosion and Management At Reculver In Kent

Coastal Erosion and Management
At Reculver In Kent
By: Jorge Narezo Balzaretti
Location
Lies to the east of London in the
county of Kent. It stretches from
Herne Bay in the west of the
county to the Wantsum Channel
in the east.
Landforms, Erosion and Longshore
drift
Land and sea meet along the coastline. The U.K. has a coastline which is
7,500 miles long. The coast is shaped mainly by the action of the waves
which reach the shore. Waves are created by the winds which blow across
the surface. Friction results in the transfer of energy from the wind to the
waves. The size of the waves depends on three factors:
the strength of the wind
the length of time that the wind blows
the distance over which the wind blows (the fetch)
The most common direction in which the waves move is determined
by the prevailing winds. In the U.K., the prevailing winds are from
the south-west which is also the direction of longest fetch. A wave
will break when it reaches shallow water. As the water rushes up
the beach it forms the swash and as it returns down the beach, the
backwash. Some waves build up beach material [constructive
waves] whilst others drag sand and pebbles down the beach
[destructive waves].
Waves erode or wear away the coast and transport the eroded
material along the coastline - a process called longshore drift.
Eventually the material will be deposited on a beach or will form a
larger feature such as a spit. Erosion works in four ways:
Hydraulic action - this results from the force of the water hitting the
cliffs.
Corrasion - this is caused by the waves picking up stones and
hurlingthem at the cliffs.
Attrition - any material carried by the waves will become rounder and
smaller over time.
Corrosion [solution] - the dissolving of rocks by sea water.
The nature of a coastline is often determined by its geology.
Some coastlines are very dramatic, with tall, vertical cliffs
whilst others are low-lying or marshy. Some coastlines are
straight for miles and miles whilst others are indented with
many headlands and bays.Long, fairly straight coastlines
result where the rocks are very similar or just one type. If
there are many rock-types and they vary in their resistance
to erosion, then headlands and bays will form.
Many areas have cliffed coastlines.
The nature of the cliff again
depends on the geology of the
rocks. Hard, resistant rocks form
tall cliffs with a jagged upper
section and a smoothed wavecut notch at the base. If the rocks
have many joints(vertical cracks)
then erosion will be greater at
some points and a cave may
form. As the waves erode back
into the cliff, the upper section
becomes unstable and eventually
collapses. In time the material
from the cliff will be eroded into
smaller and smaller pieces to
form new beach material.
If the rocks are soft, particularly
clays, then the cliffs will be lower,
caves rarely form and landslips
may be common.
Beach material almost always moves along the beach in a particular
direction which is determined by the prevailing winds. If the winds
blow the waves parallel to the shore, sand and pebbles are washed
up and back down the beach. If, however, the wind blows so that
waves come in at a sharp angle to the coast, the swash carries the
pebbles at an angle up the beach. When the backwash moves by
gravity back down the beach, the pebbles end up at a different
position. This process is repeated and pebbles gradually shift along
the beach, a process called longshore drift.
If the coastline has well
developed headlands
and bays, the headlands
often show a variety of
erosional landforms.
Joints in the headlands
are eroded back to form
caves which over time
are further eroded to
form arches. The gaps in
the headlands eventually
collapse and leave tall
stacks at the ends of the
headlands. The stacks
continue to be eroded by
the waves until only
stumps are left and these
eventually disappear
altogether.