Water On The Land Flashcards
(22 cards)
What are the characteristics of the upper course of the river?
Steep gradient V shaped valley Steep sides Narrow Shallow channel
What are the characteristics of the middle course of the river
Medium gradient
Gently sloping valley sides
Wider
Deeper channel
What are the characteristics of the lower course of the river
Gentle gradient Very wide Almost flat valley Very wide Deep channel
Name the four types of erosion
Hydraulic action
Abrasion
Attrition
Solution
Make the four types of transport
Traction
Saltation
Suspension
Solution
Why do rivers slow down and deposit material?
The volume of the river walls
The amount of eroded material in the water increases
The water is shallower (inside of the bend)
The river reaches its mouth
How are meanders formed?
The current is faster on the outside of the bend (deeper)
More erosion takes place on the outside of bend forming river cliffs
The current is slower in the inside (more friction)
Eroded material is deposited on inside of bend forming slip off slopes
How are Ox-Bow lakes formed?
Erosion causes the outside the get loser until there’s a small bit off land left between bends
The rivers breaks through this land during a flood and the river flows along the shortest course
Deposition cuts off the meander forming a sox-Bow lake
How are waterfalls and gorges formed?
Erosion
How are Flood plains and levees formed?
Deposition
What is river discharge?
The volume of water that flows in a river per second measured in cubic metres per second (m^3/s)
What factors affect river discharge?
Amount and type of rainfall Temperature Previous weather conditions Rock type Land use Relief
Why do rivers flood? (Physical factors)
Prolonged rainfall
Snowfall
Heavy rainfall
Relief
Why do rivers flood (human factors)
Deforestation
Building construction
Hard engineering methods
Dams and reservoirs- a huge walk build across rivers and a reservoir is formed behind the dam
Channel straightening- a rivers course is straightened and meanders are cut out by building artificial straight channels
Soft engineering methods
Flood warnings- the environment agency warns people about flooding through tv or radios etc
Flood plain zoning- restrictions prevent building on parts of a flood plain that are likely to be affected by floods
‘Do nothing’- no money is spent and nothing is done because it is a natural process
What are the disadvantages for hard engineering?
Dams and reservoirs- expensive to build and building reservoirs can flood existing settlements
Channel straightening- flooding may happen downstream because flood water is carried there faster and more erosion is caused
What are the advantages for hard engineering?
Dams and reservoirs- reservoirs store water which reduces risk of flooding and used as drinking wRt and HEP
Channel straightening- water moves out the area faster because it doesn’t travel as far
What are the disadvantages of soft engineering?
Flood warnings- they don’t actually stop a flood from happening and people might not hear or have access to flood warnings
Flood plain zoning- it’s no help in areas that have already been built on
‘Do nothing’- risks and impacts are reduced and it will cause a lot of damage and
What are the advantages of soft engineering?
Flood warnings- give people time to move possessions upstairs and put down sandbags and evacuate
Flood plain zoning- there aren’t any houses or roads to be damaged and impermeable surfaces aren’t created
‘Do nothing’- the rivers flood and eroded material is deposited on the flood plain which makes farmland more fertile
What is the UK’s average annual rainfall like?
North and west- high rainfall (good supply of water)
South east and midlands- high demand for water (greater demand than supply)
How does the UK manage its water supply?
Transfer water from areas with too much to areas with not enough
Build reservoirs to store more water
