Coasts Flashcards
What causes destructive wave and what are its characteristics?
Caused by large fetch where the backwash is stronger than the swash.
They are big and have higher energy.
They erode the coastline.
What causes constructive wave and what are its characteristics?
Caused by short fetch where swash is stronger than backwash.
They are small gentle waves with low energy.
They deposit sediment.
What is fetch?
The length of water a gust of wind has blown over, therefore the distance a wave travels.
What are the four types of mass movement?
Rockfall
Mudflow
Rotational slip
Landslide.
What is rockfall?
Created by the force of gravity and by freeze-thaw.
This loosens the rock.
Rock falls leaving a scree slope of rock beneath.
What is mudflow?
It occurs on slopes higher than 10 degrees and is caused by heavy rain in areas of too low vegetation to hold saturated soil in place.
Rock beneath soil is permeable.
Are very dangerous.
What is rotational slip?
Created by heavy rain which saturates soil on a curved surface with weakened rock.
Slowly slumps and slips onto curved plane.
What is landslide?
Occur after periods of heavy rain as overlying rock becomes saturated.
Rock becomes heavy and liable to to slide.
Location changes likelihood of one occurring.
What are the 6 types of weathering?
Biological, mechanical, chemical, freeze-thaw, pressure release, salt crystallisation.
What is mechanical weathering?
Where big rocks are broken into smaller fragments due to expansion and contraction, caused by ice forming in the cracks.
What is the prevailing wind?
The dominant direction of wind.
How is a wave formed?
Wind blows over sea, causing ripples to form.
Ripples swell and approach land.
Sea becomes shallower and bottom of wave slows due to friction.
Top continues to travel and forms a crest.
Crest eventually topples over forming a breaking wave.
What are the four types of transportation?
Traction, solution, saltation, suspension.
What is saltation?
When small rocks and pebbles are bounced along the river bed.
What is longshore drift?
When sediment is carried along the beach as a result of swash and backwash.
What causes backwash to travel at a 90 degree angle to the beach?
Gravity.
What are 4 depositional landforms?
Spit, tombolo, bay, beach.
What are the 4 stages of wave-cut platform formation?
Wave erosion
Cliff collapse
Retreat
Bugger wave-cut platform.
What causes sea level rise?
Thermal expansion, ice and glacial melt, post glacial rebound.
What are the threats to Tuvalu?
King tides, storm surges, groundwater flooding.
What are the social impacts of rising sea levels in Tuvalu?
- The government is required to plan evacuation of remaining 10,000 residents.
- Many people are forced away from homeland.
- Salt water intrusion is affecting agriculture and farmers.
- Cultures and traditions are being lost.
- Health problems, i.e. typhoid, from contaminated water is rising.
- The crop paluku is being destroyed and is a main source of carbohydrates.
What are the economic impacts of rising sea levels in Tuvalu?
- Salt water intrusion is affecting ecosystems.
- Cash crops are destroyed by contamination, leading to a downturn in GDP.
- Coral reef bleaching leads to reduced fish stock and therefore fish industry is affected financially.
What are the environmental impacts of rising sea levels in Tuvalu?
- Flooding and storm surges erode soils, leading to loss of plant and animal habitat.
- Warmer seas increase coral bleaching, decreasing important marine habitats.
What are the political impacts of rising sea levels in Tuvalu?
- Tuvalu relies on aid from New Zealand.
- Government are trying to get their voice heard.
