Coasts Case Studies

Question 1

What defences are at Hornsea?

Answer 1

Sea walls, groynes and rock armour

Question 2

What are the impacts of the defences at Hornsea?

Answer 2

Groynes trap the sediment and maintain the beach at Hornsea. Mappleton has been starved of sediment and waves has rapidly eroded the cliff. This is called terminal groyne syndrome

Question 3

What defences are at Withernsea?

Answer 3

A curved wall replaced the old sea wall in the 1990s following a cost-benefit analysis

Question 4

What are the impacts of the defences at Withernsea?

Answer 4

Waves are noiser when they break against the wall and the promenade is smaller.

Question 5

What defences are at Mappleton?

Answer 5

Two rock groynes which aim to prevent the removal of the beach by long shore drift. Rock armour is also used

Question 6

Impact of the defences at Mappleton?

Answer 6

At Cowden, which is 3km south of Mappleton, sediment starvation caused increase cliff erosion.

Question 7

Why is the Holderness receding?

Answer 7

Geology
Fetch
Longshore drift and beach material

Question 8

What is the geology at the Holderness?

Answer 8

Mostly consists of boulder clay- which is structurally weak, little resistance to erosion and produces shallow, sloping cliffs that are 5-20m high.
Surrounded by chalk band that creates the headland e.g. Flambrough head

Question 9

What is the fetch at the Holderness Coast?

Answer 9

• Winds and waves from the north-east with small fetch of 500-800km
• Currents (or swell) circulate around the UK from the Atlantic Ocean (large fetch of over 5000km) into the North Sea- adds energy to the North Sea waves- powerful destructive waves

Question 10

Longshore drift and beach material at the Holderness Coast?

Answer 10

• Boulder clay erodes to produce many clay particles, which are transported out to sea.
• Narrow beaches offer little friction to absorb wave energy.
• Tides flow southwards, transporting sand by Longshore drift, leaving cliffs at Holderness poorly protected against erosion.

Question 11

What is the annual rate of recession at the Holderness?

Answer 11

2 metres a year

Question 12

Where is the Holderness located to?

Answer 12

East Riding of Yorkshire

Question 13

Why is Hornsea protected?

Answer 13

• It is a regional economic centre with a population of about 8500 people
• There are important historical sites in the town
• Inland is Hornsea Mere, an important lake habitat for birds that is designated as a Special Protection Area and Site of Special Scientific Importance (SSSI).

Question 14

What is the Nile Delta?

Answer 14

A depositional landform formed from sediment brought down the Nile by floods.

Question 15

What is the Dam called on the Nile and when was it constructed?

Answer 15

Aswan High Dam, and in the 1960s

Question 16

What has the dam on the Nile caused?

Answer 16

• River discharge to drop from 35 billion m^3 per year to around 10 billion m^3.
• Sediment volume has feel from 130 million tonnes to 15 million tonnes.

Question 17

What were the changes of the dam on the Nile caused by?

Answer 17

• Water withdrawals for industry, cities and farming from the reservoir behind the dam.
• Sediment being trapped by the reservoir and dam; water in reservoir flows very slowly allowing sediment to be deposited

Question 18

What are the impacts of the dam on the Nile?

Answer 18

• Erosion rates at the Rosetta (where one of the main delta branches of the river meets the sea) jumped from 20-25m per year to over 200m per year as the delta was starved of sediment.

Question 19

What is the highest point above sea level in the Maldives?

Answer 19

2.3 m above sea level

Question 20

What would happen if there was a sea level rise of 50cm by 2100 in the Maldives.

Answer 20

The Maldives would loose 77% of their land

Question 21

What is the new artificial island in the Maldives called?

Answer 21

Hulhumalé

Question 22

What is the new island in the Maldives built from and how much did it cost?

Answer 22

Coral and sediment dredged from the seabed between 1997 and 2002
Cost US$32 million

Question 23

What is the advantage of the new artificial island in the Maldives?

Answer 23

It is a full metre higher than Malé, which may come in useful in decades to come

Question 24

What year did the Netherlands have a storm surge in?

Answer 24

1953

Question 25

What was the cause of the Netherlands storm surge (The North Sea Flood)?

Answer 25

Mid-latitude depression moving south through the North Sea generating a 5m storm surge

Question 26

What were the economic costs of the Netherlands storm surge?

Answer 26

• Close to 10% of Dutch farmland was flooded
• 40,000 bus idling so damaged and 10,000 destroyed

Question 27

What were the social costs of the Netherlands storm surge?

Answer 27

1800 deaths

Question 28

What year was there winter storms in the UK?

Answer 28

2013-14

Question 29

What was the cause of the UK winter storms ?

Answer 29

Coastal and other flooding caused by a succession of depressions and their storm surges

Question 30

What were the economic costs of the UK winter storms ?

Answer 30

Damage or around £1 billion over the course of the winter

Question 31

What were the social costs of the UK winter storms?

Answer 31

17 deaths (from all causes)

Question 32

What caused the storm surge in Bangladesh? And when did it happen?

Answer 32

The Cyclone Sidr brought it with it.
On 15th November 2007

Question 33

Why is Bangladesh vulnerable to coastal flooding?

Answer 33

• The most densely populated country in the world- estimated population of 169 million in 2015
• 46% of the population lives less than 10 metres above sea level
• Deforestation of coastal mangrove forests has removed vegetation that once stabilised coastal swaps and dissipated wave energy during tropical cyclones.

Question 34

What was the max wind speed of Cyclone Sidr and what was the storm surge height in metres?

Answer 34

223km/h and 4.5-6.0 m

Question 35

What were the economic impacts of the cyclone Sidr?

Answer 35

• The high winds and floods damaged housing, roads, bridges and other infrastructure
• Electricity supplies and communications were knocked our, and roads and waterways became impassable.
  Total costs to Bangladesh estimated to be US$1.7 billion

Question 36

What are the social costs of cyclone Sidr?

Answer 36

• Drinking water was contaminated by debris, and many freshwater sources (such as wells) were inundated with salt water.
• The sanitation infrastructure was destroyed raising the risk of disease.
• Over 4000 people died and over 55,000 people were injured