Year 8 - Topic 4 - Water On The Land Flashcards
What is erosion?
The wearing away of land/rock. This is caused by the power of moving water such as water in a river or by the sea at the coast. Erosion causes the shape of the land to change.
What are the four types of erosion?
Abrasion
Attrition
Solution
Hydraulic Action
What is abrasion?
Rocks carried by water scrape off surfaces, wearing them away
What is attrition?
Rocks carried by the water smash into each other and wear away
What is solution?
Particles of rock can be dissolved by water
What is hydraulic action?
Water forces air and water into existing cracks and weaknesses, causing the cracks to become larger and weaken
What is transportation (of sediment)?
The power of the water carries sediment to different places. This is called transportation. The material that it transports is called the sediment
What is deposition?
As the sediment is moved downstream, some is dropped. This is called deposition
What three sections are rivers divided into?
Upper course
Middle course
Lower course
Is the gradient of the upper course steep, gentle or very gentle?
Steep gradient
Is the gradient of the middle course steep, gentle or very gentle?
Gentle gradient
Is the gradient of the lower course steep, gentle or very gentle?
Very gentle
What shape is the valley of the upper course?
V-shaped valley
What shape is the valley of the middle course?
Wider valley, flat floor
What shape is the valley of the lower course?
Very wide valley and flat
What is the river like in the upper course?
River is narrow, shallow and turbulent
What is the river like in the middle course?
River is wider and deeper
What is the river like in the lower course?
Widest, deepest river
What is the size of the load in the upper course?
Large bedload (rocks and boulders)
What is the size of the load in the middle course?
Has small material in the load
What is the size of the load in the lower course?
Has mainly suspended load (very fine and small)
What process occurs in the upper course?
Mostly erosion
What processes occur in the middle course?
Mostly erosion and deposition
What process occurs in the lower course?
Mostly deposition
What is a coastline?
A coastline is where land ends and the sea starts
What features can be found at different coastlines?
Beaches Caves, arches, stacks, stumps Sand dunes Cliffs Destructive waves and constructive waves
What are glaciers?
Glaciers are huge rivers of ice that flow downhill very slowly. Glaciers scrape and shape the land that they flow over
Glaciers shape the land when they flow in three main ways. What are they?
Abrasion
Plucking
Freeze-thaw weathering
What is abrasion (for glaciers)?
Pieces of rock that are attached to the base of the glacier are dragged along the valley floor when the glacier is flowing. They scrape and erode the ground as they move
What is plucking (for glaciers)?
Pieces of rock that are attached to the base of the glacier become loose when the base starts to melt. The fragments are ‘plucked’ from the ground layer when the glacier moves, eroding the land underneath
What is freeze-thaw weathering?
Water gets into cracks in rocks. When it freezes it expands by 9%. This process repeats over time and the constant freezing and expansion causes the cracks to weaken and fragments of rock break off
How can prolonged and heavy rainfall lead to flooding?
Prolonged and heavy rainfall makes the ground saturated, leading to flooding
How can snowmelt lead to flooding?
Snowmelt creates lots of surface run-off, leading to flooding
How can steep land lead to flooding?
Steep land close to rivers increases the chances of flooding as rainfall travels quickly downhill and into rivers
How can deforestation lead to flooding?
Taking away the roots and leaves of trees means more rainwater collects on the ground
How can humans’ building settlements lead to flooding?
Humans’ building settlements can increase the chance of flooding as it makes the ground less permeable
Is water distribution around the world even?
No. Many countries are experiencing water stress and shortages which is mostly related to a desert climate and the countries receiving very little rainfall
What do people use water for?
Agricultural, industrial and domestic purposes
How long is the River Nile?
It travels for 6,695km
The Nile passes through 11 countries. What are they?
Burundi Egypt Eritrea Ethiopia Kenya Rwanda Sudan South Sudan Tanzania Uganda Democratic Republic of the Congo (DRC)
When and where was the Aswan High Dam built and what does it control?
The Aswan High Dam was built in Egypt. This huge dam controls the flow of the river to generate electricity, irrigate (water) farms and provide homes with drinking water
How much of Egypt’s population depend on the Aswan High Dam’s water?
More than 95% of Egypt’s population depend on its water and live within a few miles of the river banks
What did Ethiopia do that started a dispute?
Ethiopia also built a dam that was $4.5 billion called the Grand Ethiopian Renaissance Dam (Africa’s largest, with a reservoir about the size of London)
Why did the Egyptians start a dispute with Ethiopia because they built a dam?
The dam will reduce the amount of water in the Aswan Dam in Egypt and they worry that the Dam will allow Ethiopia to control the flow of the river
What is a dam?
A huge wall across the river, forming a reservoir (lake) behind the dam to store water
