GEOGRAPHY COURSEWORK
BY
A. Student
Should Dunwich be defended
from coastal erosion?
Introduction
Aims of the project
The purpose of this coursework is to collect enough information so we can answer the
question “Should Dunwich be defended from coastal erosion?”
We will also be able to learn about coastal erosion and other coastal processes.
About Dunwich
Dunwich is a small village on the east coast of Suffolk. It has a beach and attracts
tourists in the summer. It is a quiet, rural area with Southwold to the north and Sizewell
power station to the south. It is a sparsely populated area.
Issues and values
If Dunwich was defended from coastal erosion it would affect other places in the
surrounding area along the same part of the coast and we need to decide if it is
worthwhile. We need to decide which measures would be cost-effective and if any
propose coastal defences would be harmful to the environment. But whatever the answer
there will be some people against the idea and some for it. I will need to develop my own
opinions and values.
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Key questions
Where is Dunwich?
It is a small town in the Suffolk Coastal district of the county of Suffolk, England, on the
North Sea coast. The first development on the site was probably a Romano-British
community, and in Anglo-Saxon days it became the most important commercial centre in
East Anglia. Early in the 7th century, when Sigebert became king of East Anglia,
Dunwich was chosen as his capital, and a bishopric was founded before 650. The
community received a charter from King John (reigned 1199-1216). Dunwich became a
wealthy port, but severe coastal erosion caused its decline. In 1347 more than 400 houses
were washed away in a storm, and similar disasters occurred in 1570. Until 1832,
Dunwich returned two members to Parliament in spite of its small population. The
corporation was abolished in 1886. Pop. (1981) 129.
How has Dunwich been affected by erosion over the years?
Over the past 400 years approximately one metre of land per year on average has been
eroded
What coastal processes operate and what coastal features are there at Dunwich?
This is covered in the next chapter where a beach profile and a cliff profile are discussed
What coastal defences are there?
In the 15th Century, the inhabitants of the village devised a way of defending the coast.
Each autumn they would tie up piles of wood and shingle and place them at the base of
the cliffs. This was a very effective method of defence for over 200 years. There are not
many coastal defences at Dunwich, just some sand dunes and clay banks. These are not
very good defences as the sand dunes are worn away by people walking on them and the
only thing holding them together is Marram grass.
What options exist for defence against coastal erosion?
The following options exist:
Rock revetment – approximate cost $4500 per metre of coast, but variable.
Offshore rock barrier (breakwater) – approximate cost £6500 per metre.
Wave return wall – cost £6000 per metre of coast.
Groynes – Approximate cost: £5000 per groyne
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Data Collection
History of erosion
In the 5th Century Dunwich was a port on the bay shoreline, approximately 2 KM from
the open sea.
From 1587 – 1702 107m of land was removed. Between 1702 and 1754 a further 160m
was eroded and up to 1973 121m were removed. In 386 years, 388m of coastline have
been lost (approximately 1m per year), although this has not been true in all areas.
Most rapid erosion rates over 5 years are:
South of Millgate Street
South of Greyfriars
All Saints graveyard
4 feet
14.5 feet
11.5 feet
4
Beach Profile
3.5
3
Weight (m)
2.5
2
1.5
1
0.5
0
1-2
2-3
3-4
4-5
Pole number
5
5-6
6-7
Cliff Profile
This shows the cliff profile that I did on the visit to Dunwich, so that we could see what
the land is made of and whether it is prone to erosion.
Brown soil
15cm
Orange/grey soil
15cm
Light grey soil
30cm
Humus – decomposed plant matter
Sand & clay
1 – 1.5m
Pebble – old river bed
Orange sand with clay
Dark orange/brown iron pan
Small grain sand
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Data Analysis
Timeline
In the 5th century Dunwich
was inland, approx. 2KM
from the sea
1587
107m of land
removed
1702
160m eroded
1754
121m eroded
1973
7
Graph to show pebble size
Pebble size
60
50
Pebble size (mm)
40
30
20
10
0
1-2
2-3
3-4
4-5
Pole Number
8
5-6
6-7
Graph to show beach profile
3.5
3
Weight (m)
2.5
2
1.5
1
0.5
0
1-2
2-3
3-4
4-5
Pole number
9
5-6
6-7
Cliff composition
Brown soil
Orange/grey soil
Light grey soil
15cm
15cm
30cm
Humus – decomposed plant matter
Sand & clay
1 – 1.5m
Pebble – old river bed
Orange sand with clay 15cm
Iron pan
Small grain sand
To bottom of cliff
10
Field sketch
pylons
Inlet and outlet
pipes
Sizewell A & B
Marram grass
sea
Clay barrier
Sand dunes
Beach
lagoons
forest
marshland
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Coastal defences
Rock revetment
5 to 10 tonnes hard
rock armour
Filter layer of smaller
rock as a base for rock
armour
Offshore rock barrier
About 200m offshore
12
Rock barrier to
dissipate wave
energy before waves
reach the shore
Conclusion
What is the best decision for coastal management at Dunwich?
After gathering all this information about Dunwich I have come to the conclusion that it
is too late for Dunwich to be defended from coastal erosion. This is because there is
nothing left to defend except the houses, so there is no point in spending money on
defending Dunwich.
If any money was to be spent then only soft defences should be used.
Defending Dunwich from coastal erosion could also have serious repercussions along the
coast and it should not be forgotten that the Sizewell A and B Power Station are a little
way along the coast
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