Everything you need to know for Water on the Land

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River course
The path of a river as it flows downhill
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The part of the valley the water occupies
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The area of land which the river runs through
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Upper course
V-shaped, steep valley. Narrow, shallow channel
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Middle course
Gently sloping valley sides. Wider, deeper channel
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Lower course
Wide, flat valley. very wide, deep channel
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Hydraulic action
The force of water hitting the channel and breaking parts away
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Rhe action of river sediment being carried by the water and scrape and rub against the channel, wearing it away
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Rocks and sediment carried by the river bumping against each other and wearing down
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Solution (erosion)
River dissolving some types of rock such as chalk or limestone
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Solution (transportation)
Soluble rock is carried in the river
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Small sediment particles are carried with the river flow
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Larger sediment is bounced along the river bed
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Large rocks/ boulders are rolled along the river bed
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The river loses speed and energy and deposits eroded material that it is transporting
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Reasons for deposition
The river loses volume. The amount of sediment increases. The river is shallower. The river has reached its mouth
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How meanders are formed 1)
Meanders are formed in the lower parts of a river course. The river flows faster on the outside of a bend because the channel is deeper, so more erosion happens there (forming river cliffs)
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How meanders are formed 2)
The water flows slower on the inside of a bend due to friction. Eroded material/ sediment is deposited and a slip-off slope forms
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Ox-bow lake 1)
Outside bend becomes larger and closer together, separated by a small section of land called a neck
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Ox-bow lake 2)
The river breaks through the neck (usually during a flood) and cuts off the bend
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Ox-bow lake 3)
Deposition occurs and cuts off the meander
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Waterfalls 1)
Occurs when river flows on areas of hard rock and then soft rock.
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Waterfalls 2)
The softer rock erodes quicker and forms a step in which water flows over and forms a waterfall and a plunge pool
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Gorge 1)
Sediment in the plunge pool erodes the underside of the hard rock (abrasion)
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Gorge 2 )
The hard rock is undercut and collapses, adding more sediment into the plunge pool
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Gorge 3)
The process repeats until the waterfall retreats back up the channel and a steep sided gorge is formed
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Flood plain
The wide valley in the lower course which usually gets flooded. Deposition from flooding and formed meanders make it higher
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When a river floods it deposits the heaviest material closer to the banks. The sediment builds up and forms raised sides along the edges
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River discharge
The volume of water that flows IN the river per second
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Hydrograph peak discharge
The highest (point on the curve) discharge in an amount of time
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Hydrograph lag time
Delay between peak rainfall and peak discharge
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Hydrograph rising limb
The increase in discharge as rainfall flows into river
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Hydrograph falling limb
Decrease in discharge as river returns to normal level
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Amount + type of rainfall
Heavy, frequent rain = more runoff = lag time decrease = river discharge increase
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Hot and dry OR cold and freezing = hard, impermeable land = increased run off = river discharge increase
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Previous rain
Land is saturated so no more water can infiltrate = increases run off = increased discharge
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Permeable rock
Water can infiltrate rock and flow underground = decreased run off = increased lag time = decreased discharge
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Impermeable rock
Water cannot infiltrate so has to flow above land = increasing run off = increasing discharge
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Urbanised areas (human)
Impermeable surfaces e.g concrete increases run off and drainage systems increase discharge
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Steep slopes
Increased run off = decreased lag time = increased river discharge
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Deforestation (human)
Tree leaves intercept rainwater and roots store it in the ground. A decrease in trees means an increase in run off
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Carlisle flood case study
In a rich part of the world (England). River Eden flooded January 2008
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Carlisle causes
Heavy rainfall (200mm in 36 hours) saturated soil and increased run off into the river. Urbanised area with impermeable materials increased run off. River discharge reached 1520 cumecs
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Carlisle primary effects
3 deaths. 3000 homeless. 4 schools flooded. 350 business shut down. 70,000 homes lost power. Damaged infrastructure. Rivers polluted
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Carlisle secondary effects
Children lost education. Stress related illnesses were common. 3000 jobs were at risk
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Immediate responses
People evacuated. Food and drinks given out at reception centres. Temporary accommodation set up
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Long term responses
Community groups set up to give people emotional support and practical help. Flood defence schemes set up e.g building a bank
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Bangladesh flood case study
In poor part of world. Rivers Brahmaputra and Ganges flooded July and August 2007
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Bangladesh causes
Heavy rainfall (900mm) in July saturated soil and increased run off. Melting ice in Himalayas. Both rivers reached peak discharge at same time
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Primary effects
Over 2000 deaths. 25mil homeless. 44 schools destroyed. Factories closed and livestock killed. 10,000km road destroyed. 112,000 houses destroyed. Rivers polluted
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Secondary effects
Education suffered as 4000 schools affected. 100,000 people caught water borne diseases. Flooded fields reduced yields (basmati rice price increased by 10%). High unemployment
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Immediate responses
Many people couldn't evacuate due to blocked roads. International charities provided aid and supplies. Rescue boats sent to help those who were stranded
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Long term responses
International charities funded rebuilding of homes, agriculture and some industries. Some homes rebuilt on stilts to help withstand future floods
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Water surplus
Supply is greater than demand e.g North and West of England
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Water deficit
Demand is less then supply e.g Midlands and South East England
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UK water demand
Over past 25 years, water demand has increased by 50%. Population to increase by 10mil over next 20 years
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Managing water supply
Water transfer. Reservoirs. Fixing leaky pipes
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Water transfer
Transfer water from areas of surplus to areas of deficit to manage demand
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Economic issue of water transfer
Dams and aqueducts used to store and transport water are expensive
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Environmental issue of water transfer
Wildlife disrupted such as fish migration patterns
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Political issue of water transfer
People may not want water in their area being used/ taken elsewhere
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Store water so increase water supply, however can involve flooding settlements to build
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Fixing leaky pipes
Millions of litres are lots every day due to leaky pipes around London
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Reducing demands of water
By using less water at home e.g showers instead of baths, and owning water metres
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Water metres
Charge people for the exact volume of water (every drop) they use so they are more careful
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Channelisation (hard engineering)
Artificially straightening or deepening the channel to make it more efficient
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Advantages of channelisation
Effectively protects immediate area as water is moved away quickly
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Disadvantages of channelisation
Expensive and must be continually done. May cause flooding downstream as water is carried there faster
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Flood walls (hard engineering)
Built to prevent banks from breeching and allow a higher river discharge.
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Advantages of flood walls
Do not take up much space and are easily erected
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Disadvantages of flood walls
Water may circumnavigate around wall when flooded. Water may get through cracks in wall and weaken it
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Dams (hard engineering)
A giant structure built to store water. Three Gorges in China cost £25bn
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Advantages of dams
Efficient at protecting against flooding. Hydroelectric power (HEP) can be generated. Water can be stored for drinking + droughts. Total control over river flow
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Disadvantages of dams
Settlements behind dam flooded (1.2 mil people made to move for Three Gorges). Affects biodiversity. Areas downstream are not flooded so soil is not fertilised from sediment. Very expensive
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Artificial wetlands (soft engineering)
Allows an area to flood, reducing discharge downstream
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Advantages of artificial wetlands
Cost effective. Wetlands provide habitat. Sediment enriches soil
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Disadvantages of artificial wetlands
Agricultural land lost and becomes land which is unable to be built on
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Afforestation (soft engineering)
Planting trees to increase interception and decrease run-off
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Advantages of afforestation
Low cost. Improves quality of environment and prevents soil erosion. Is natural to look at
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Disadvantages of afforestation
Delayed success as takes time to grow. Conifer trees make soil acidic. Increases fire risk
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Flood alerts (soft engineering)
Media used to send warnings and inform people on the likelihood of flooding
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Advantages of flood alerts
Increases awareness and people's safety as they have a faster reaction
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Disadvantages of flood alerts
Does nothing to stop or decrease the intensity of flood
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Land use zoning
Gives land uses based on flood occurrence level
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Zone A
Lowest value or essential construction only
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Zone B
Little and flood proof development
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Zone C
More development but residents warned of risks and how to react
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Advantages of Land use zoning
Decreased number of people and buildings affected
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Disadvantages of land use zoning
Does nothing to stop or decrease the intensity of flood
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Card 2


The part of the valley the water occupies



Card 3


The area of land which the river runs through


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Card 4


V-shaped, steep valley. Narrow, shallow channel


Preview of the back of card 4

Card 5


Gently sloping valley sides. Wider, deeper channel


Preview of the back of card 5
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