River processes and Pressures Flashcards
What happens to the gradient of a river as you go away from the source?
The gradient becomes shallower
What happens to discharge as you go down a river away from the source?
The discharge start small and becomes very large towards the lower course
What happens to the depth of the river as you go down it away from the source?
The Depth Becomes deeper
What happens to the Channel shape as you go down a river away from the source?
The shape begin to narrow with steep sides in the upper course. Then in middle course it becomes flat with steep sides. In the lower course it becomes a flat floor with gently sloping sides.
What happens to velocity as you go down the river wey from the source?
It starts off quite fast and towards the lower course is very fast
What happens to the valley shape as you go down a river away from the source?
It starts with steep sides and then toward the lower course has gently sloping sides.
What are the features of the upper course?
There are waterfalls and interlocking Spurs.
What are characteristics of the middle course?
Meanders and floodplains
What are characteristics of the lower course?
Meanders, floodplains, levees and oxbow lakes
What are interlocking Spurs?
Interlocking spurs are ridges and Valleys sides which meet together with the opposite Valley.
How do waterfalls cause erosion?
- they are bands of more resistant rock that lay over less resistant rocks
- the water pours over the edge into a plunge pool which causes erosion undercutting the hard resistant Rock
- This erosion causes a overhang to form
- after a while the overhang can no longer be supported hence the harder rock collapses.
What are meanders?
Bends in the rivers’ course
How are oxbow lakes created?
This is where meanders form and the neck of the meander narrows, eventually cutting off and forming an oxbow lake
On a corner of a meander what side does erosion happened and what side does deposition occur?
Outer - faster = erosion
Inner - slower = deposition
How are levees formed on a river?
As the water floods over the bank of the river the water does not have enough energy to carry larger silt particles. As a result the silt build-up causing levees to form.
What is a delta and how is it formed?
A delta is formed when the water in the River slows down as it approaches the mouth this is normally where the ground is flat causing the channels to fill up with sediment and the river splits and spreads into many different streams
What are the impacts of climate on River landscapes and sediment load?
Erosion rate, transportation rate, weathering and amount of discharge.
How does climate have an effect on a erosion rate?
In wetter climates there is generally more erosion as more water enters the river through rainfall
How does weathering become affected by climate?
Weathering can be caused by fluctuation of temperature e.g. freeze thaw
How can climate impact transportation rate?
In wetter climates transportation is greater.
How is amount of discharge affected by climate?
In what a climates discharge is greater hence there is a higher transportation rate
What is the equation for discharge of a river?
Area x velocity
What are the two types of slope processes that are caused by rivers?
Soil creeping and slumping
What is soil creeping?
Particles of soil slowly move down the sides of Valleys under the influence of gravity
What is slumping?
When valley sides are eroded by Rivers making them steaper and more prone to downward movement
On a hydrograph what does the line represent?
Discharge
On a hydrograph what is lag time?
The difference in time between the peak of the rainstorm and the peak of the River discharge
What physical factors that cause lag time to shorten and limbs to be steep?
- Soil type - impermeable soils absorb less water
- geology - more resistant rock will absorb less hence more run off
- vegetation - less = more run off
- slope - steeper
- drainage basin shape - wide with lots of tributaries - water enter river quicker
- anticedent conditions - more saturated with water prior to storm
What human activities contribute to flooding?
Urbanisation, land use change, deforestation and building on floodplains
When were the Tewkesbury floods?
2007
What physical causes of flooding affected the Tewkesbury floods?
- the River Severn went through mountains and hills at source to increase surface run off
- west of UK usually experiences heavy rainfall
- 2 of the largest rivers in the UK meet in Tewkesbury - Severn + Avon
- also contributes to the discharge of the River Severn
What human processes were involved in the Tewkesbury floods?
- urbanisation cause the town to grow, as a result there was less soil to absorb water
- recently built houses on the floodplain
- Field drains on the mountains of Wales improved Farmland but they quickly move water into the tributaries of the seven contributing to flooding downstream
How does climate change increase flood risk?
- increasing frequency of storms
- warmer periods cause soil to bake
- colder periods cause the soil to freeze
What are 4 threats to people?
- Damage to housing
- Damage to crops or farms that decreases food supply
- Death and injury
- Damage to fresh water and electricity supply
What are 4 threats to the environment?
- Death or injury to animals
- Damage to wildlife habitats
- Stress to animals - rescue
- Damage to trees and plants - decrease biodiversity
What are 4 hard engineering methods?
- Embankments and Levees
- Flood walls
- Dams and reservoirs
- Flood Barriers
Pros and cons to embankments and levees?
- Use of natural materials so it blends in with surroundings
- May burst, causing widespread flooding
Pros and Cons of Flood walls?
- Require minimal maintenance
- Blocks the view of the river
Pros and Cons of Dams and Reservoirs?
- Able to regulate and control the flow of water
- Very expensive to build
Pros and Cons of Flood Barriers?
- Can be moved to where needed and quickly erected
- Don’t provide long lasting protection
What are 4 methods of Soft engineering?
- River restoration
- Wash lands
- Floodplain retention
- Plant trees - afforestation
Pros and Cons of river restoration?
- can reduce flooding downstream
- People may not want land use to change
Cons of wash lands?
- Restricts economic developement
Pros and cons of flood plain retention?
- Provides somewhere for flood water to go
- Attractive and provides space for leisure and recreation
- Restricts economic developement
Pros and Cons of river afforestation?
- Increased infiltration
- Not suitable for all locations
Disadvantages of different data presentation methods:
Bar graphs - doesn’t show relationship between categories
Triangular graphs - data must be in %
Choropleth maps - hides variations within areas
Pie charts - lots of small segments make it hard to interpret
Scatter graph - can only show relationships between two variables
What are rural settlements?
in the UK, settlements with fewer than 10,000 inhabitants - fewer than 3000 in Scotland
Conurbation?
When a city has expanded outwards and absorbs smaller settlements that used to be seperated
Urban core?
the central part of a conurbation - high population density
Urban Fringe?
the settlement areas around the edge of the urban core - low density
Population density?
the number of people per square km
(3) economic differences:
- many people who live in rural areas work in urban areas
- More primary sector in rural areas e.g. fishing
- Rural settlements generally have lower wages than urban cores
Policies to reduce economic differences between rural and urban areas:
- EU’s European regional Development Fund - £2.6 Billion
- Enterprise zones - regions with tax cuts and super fast broadband to attract businesses to specific regions
2 facts about immigration:
- in 2015, 13% of people living in the UK were foreign born - 8 million
- In 1961 only 3 percent living in the UK were foreign born
In the past 50 yrs what sector has grown most in the UK?
Tertiary which has taken over the previously dominant Secondary sector.
What was the 2016 goal for UK immigration?
To reduce the level of net migration to 100,000 people per year
What is globalisation?
the process by which trade and investment build more and more connections between countries
What is FDI?
Foreign Direct Investment - when people in one country invest in businesses in another country to the extent that they gain significant control over how those businesses are run
What are TNC’s?
Transnational Corporations - businesses run from one country that have control over enterprises in other countries
2 reasons why FDI has increased in the UK?
- Globalisation is strong in banking and finance
- The government has encouraged FDI by privatising industries and allowing foreign companies to buy them
What are 2 advantages of TNC’s?
- Investment
- Innovation
What are 2 disadvantages of TNC’s?
- Security
- Competition
What are the 4 different parts of a city?
- CBD
- Inner city
- suburbs
- rural-urban fringe
Why was Birmingham a key location for urban growth in the industrial revolution?
Canals
What is deprivation?
not having access to the same resources and opportunities as other people
What is IMD?
Index of Multiple Deprivation - Scores small area across the whole of the UK on a number of measures
What is deindustrialisation?
industries moving out of cities to cheaper locations
What is decentralisation?
Where shopping centers and shops were built in the suburbs
What is sprawl of rural to urban fringe?
When demand for housing increases and as a result houses are built on the rural-urban fringe expanding it
What is gentrification?
When wealthier people move to cities with cheap property, pushing poorer individuals out
What is Studentification?
When large amounts of students travel and move to a city to study. As a result this causes areas of the city become dominated by students and student housing
What are positive impacts of regeneration?
- job opportunities
- better access to facilities e.g. cinemas
- Derelict, dangerous housing is removed
What are negative impacts of regeneration?
- The area may become to expensive for poorer individuals
- new jobs may be poorly payed
- A city may loose individuality
What are 6 ways to make urban living in the UK more sustainable?
- Renovate old buildings
- Use brownfield sites for development
- Improve public transport systems
- Build new housing that is energy efficient and cheaper
- Involve local communities in decision making
- Reduce waste
Give 3 ways in which rural and urban areas’ relationship is beneficial:
- Economic - work
- Social - hospitals
- Environmental - access to pleasant rural landscapes
Give 3 ways in which rural and urban areas’ relationship is negative:
- Economic - decentralisation has caused businesses to move to rural-urban
- social - rural locations become too expensive for local young people to live there
- Environmental - development of greenfield sites make rural areas more urbanised
What are 3 features of an expanding commuter village?
- richer newcomers and poorer locals
- many young families
- many older people retiring and moving away from the city
Why do rural areas experience economic and social changes?
- pressure on housing
- population change
- change in services
- commuter lifestyles
