Coasts Case Studies Flashcards
What defences are at Hornsea?
Sea walls, groynes and rock armour
What are the impacts of the defences at Hornsea?
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
What defences are at Withernsea?
A curved wall replaced the old sea wall in the 1990s following a cost-benefit analysis
What are the impacts of the defences at Withernsea?
Waves are noiser when they break against the wall and the promenade is smaller.
What defences are at Mappleton?
Two rock groynes which aim to prevent the removal of the beach by long shore drift. Rock armour is also used
Impact of the defences at Mappleton?
At Cowden, which is 3km south of Mappleton, sediment starvation caused increase cliff erosion.
Why is the Holderness receding?
Geology
Fetch
Longshore drift and beach material
What is the geology at the Holderness?
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
What is the fetch at the Holderness Coast?
- 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
Longshore drift and beach material at the Holderness Coast?
- 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.
What is the annual rate of recession at the Holderness?
2 metres a year
Where is the Holderness located to?
East Riding of Yorkshire
Why is Hornsea protected?
- 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).
What is the Nile Delta?
A depositional landform formed from sediment brought down the Nile by floods.
What is the Dam called on the Nile and when was it constructed?
Aswan High Dam, and in the 1960s
What has the dam on the Nile caused?
- 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.
What were the changes of the dam on the Nile caused by?
- 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
What are the impacts of the dam on the Nile?
- 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.
What is the highest point above sea level in the Maldives?
2.3 m above sea level
What would happen if there was a sea level rise of 50cm by 2100 in the Maldives.
The Maldives would loose 77% of their land
What is the new artificial island in the Maldives called?
Hulhumalé
What is the new island in the Maldives built from and how much did it cost?
Coral and sediment dredged from the seabed between 1997 and 2002
Cost US$32 million
What is the advantage of the new artificial island in the Maldives?
It is a full metre higher than Malé, which may come in useful in decades to come
What year did the Netherlands have a storm surge in?
1953
