Water on the Land Flashcards
Transpiration
Plants giving off water vapour
What is water running through soil called?
Percolation
Surface Runoff
Water running over the ground
What is meant by the Watershed?
The boundary dividing two drainage basins
What does the long profile show?
The long profile shows how the height and gradient of a river changes as it travels downstream.
What does the cross profile show?
How the river basin and bed change as the river travels downstream
How do the height and gradient of the river change as it moves downstream?
The height gets shorter, the gradient gets less steep
What are the four types of erosion?
Abrasion
Attrition
Hydraulic action
Solution / corrosion
What is abrasion
Rocks in the river wear down the river bed
What is attrition?
Rocks being carried in the river smash into each other and break into smaller rocks
What is corrosion/solution?
Soluble particles are dissolved into the river
What is hydraulic action?
The force of the river against the bank and bed weakens and breaks it
What is lateral erosion and where is it found?
Lateral erosion is found in the lower course and it the river eroding outwards widthways and can lead to river migration
What is vertical erosion and where is it commonly found?
Vertical erosion is the downwards erosion of a river creating steep valley sides and often found in the upper course of the river. It is pulled down due to gravity
In what four ways is sediment transported in a river?
Solution
Suspension
Saltation
Traction
How is sediment carried through solution?
Minerals and sediment are DISSOLVED into the river and carried as a solution
What is suspension?
Fine, light material is carried along in the water
What process bounces small pebbles along the river bed?
Saltation
What is traction?
Large boulders and rocks are ROLLED along the river bed
What methods of transportation are common in the upper course?
Traction and Saltation
What methods of transportation are common in the middle course?
Suspension and solution
Where is sediment most commonly transported through suspension and solution?
The lower / middle course
What landforms are created in the upper course and are they created due to erosion or deposition?
Waterfalls and gorges due to EROSION
What landforms are commonly found in the middle course and how do they occur?
Meanders and oxbow lakes due to EROSION and DEPOSITION
Where would you find landforms created by deposition?
In the lower course
eg
Levees / floodplains
What is alluvium?
Clay, silt, and sand carried and deposited by the river in the lower course typically creating fertile land
What is meant by helical flow?
Helical flow is the corkscrew flow of water in a meander that leads to the creation of a slipoff slope
What does the difference between peak rainfall and peak discharge on a hydrograph represent?
The lag time
What is the rising limb?
Where the river discharge is growing
What is the falling limb?
Where the river discharge is falling, post peak discharge
What factors affect a hyrdrograph (how quickly a river reaches peak discharge)
Geology and soil Gradient of valley sides Land use Amount of precipitation Drainage density
What factors affect the river discharge and lagtime?
Rainfall
Temperature
Gradient / relief of area
Rock type
Urbanisation
Deforestation
What caused the Boscastle flash flood on March 16 2004?
- Local area saturated by weeks of rainfall
- High amount of rain in short time -> 15mm in 15mins
- Impermeable rock reduced infiltration
- Steep V- shaped valleys increased runoff
- Confluence of 3 rivers
( Valency, Jordan, Paradise) - Carparks either side of river increased runoff
What were the effects of the Boscastle flash flood on March 16 2004?
- 3m wall of water destroyed infrastructure
- Silt and debris left afterwords
- Visitor centre collapsed
- Tourism reduced affecting economy massively
- £15mil in damage claims
What were the short term responses to the Boscastle floods?
- Flood warnings issued
- Rapid evacuation
- Fire brigades and police on scene within hour
- RAF air craft save 150 people
- Temporary accomodation on football pitch
- Lifeboats rescue people from housing
What were the long term responses to the Boscastle floods?
- North Cornwall council ban residents returning home for first ten days to repairs can take place
- Extensive clean up of silt and debris mean residents home within 6 months
- Telephone, water, electricity, and gas supplies reinstalled within 6 months
- Insurance and compensation awarded to homeowners
Where is Pakistan?
Pakistan is in Asia bordered by India to the east and Afghanistan to the west
What caused the Pakistan floods in 2010?
- Heavy monsoon rain lead to saturated ground
- High surface runoff due to steep gradient and impermeable rock on Himalaya mountains
River Indus broke banks on 9 August flooding the Swat Valley the worst
What were the effects of the Pakistan floods?
- 1600 dead
- 14 million impacted
- Sukker Barrage dam breached worsening flooding
- Farmland ruined by silt deposition
- The Swat Valley in the north was cut off
- Dirty and contaminated water led to outbreaks of Typhoid and Cholera
What were the responces to the Pakistan floods in august 2010?
- Slow response cause death toll to rise
- Reliance on international aid
- Swat Valley cut off and aid had to be given by donkeys which took a long time
- Taliban supplied aid in North to win over communities
- Cholera epidemic
What are the differences between hard and soft engineering?
Hard engineering structures are more expensive, effective, and offer the greatest change to the environment. Soft engineering is often more natural, cheaper, sustainable although not necessarily permanant
What are examples of soft engineering?
Bank zoning
Tree planting for interception
Areas for rivers to deposit sediment
What are examples of hard engineering?
Dams
River widening
River straightening
River walls
Where is the three gorges dam, what is its purpose, and how much did it cost?
Location: Yangtze river, China
Purpose: - Reduce risk of flooding downstream from 1/10 to 1/100 (years)
- Produce power with 32 turbines / 18000 megawatts
Cost: $39 billion
What have been the benefits of the Three Gorges Dam in China?
- HEP produced for growing Chinese population
- Less flooding further down the river
What have been the disadvantages of the Yangtze river?
- 1.4 million relocated
- 13 cities, 140 towns and 1300 villages upstream submerged
- No compensation
- Prevents deposition of alluvium, leading to infertile land
- Most polluted reservoir on earth = 265billion gallons of raw sewage pumped in every year
What is an example of river straightening?
Mississipi river USA
Pros:
- Faster river
- Water moves away from city more quickly
Cons:
- Further flooding downstream
What is an example of afforestation?
Yellow river, China
Pros:
- Planting trees increases interception
- Increases lagtime
- 20% increase in trees in last two years
- Lessens impacts of floods
- Provides habitats and employment
Cons:
- Lessons impact but does not stop completely
- Insurance for properties is high
Why has water demand risen?
- Rise in water intensive appliances (64-96%)
- Cooking
- Washing
- Drinking
- Toileting
in UK person uses 150l a day
in Africa person uses 48l a day
Where are the areas of surplus in the UK?
In the South east (+west)
How can water levels in an area of defecit be helped?
Kielder water reservoir in Northumberland is a water transfer scheme
What are the negatives of Kielder water reservoir?
- Cost £167 million
- Habitats, farmland, homes, and infrastructure all lost
What are the postives of Kielder water reservoir?
- Largest man made reservoir in Europe
- Reliable supply of water to north east
- Manages flow of River Tyne and so protects Newcastle from flooding
- Free recreational activities
- Provides water habitats
- It is a conservation area
