Water on the Land

  • Created by: KateStoc
  • Created on: 29-12-16 16:11
Describe 4 ways river transports material.
Traction- Large particles (e.g. boulders) are pushed along the bed by the force of the river. Saltation- pebble-sized particles are bounced along the bed. Suspension- small particles are carried by the water. Solution- soluble material is dissolved.
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Describe 4 ways how rivers erode material.
Hydraulic action- The force of the river breaks rock particles. Abrasion- Rocks scraps against the channel, wearing it away. Attrition- rocks rub together to become smaller and rounded. Solution- river water dissolved rocks e.g. chalk and limestone.
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How is the outside of a meander different to the inside of a meander?
The current is faster on the outside of a meander. This means that erosion (River cliff) occurs on the outside of a meander and deposition (slip-off slope) occurs on the inside of a meander.
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How is the upper course of a river different to the lower course?
The upper course of a river has a steeper gradient than the lower course. The upper course has a V-shaped valley with steep sides whereas the lower course had a very vide, almost flat valley.
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How is the upper course of a river different to the lower course? (Continued)
The upper course has a narrow, shallow channel compared to the lower course that has a wide and deep channel.
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What does the long profile of a river show?
The long profile shows the gradient of the land.
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What does the cross profile of a river show?
The cross profile shows a cross-section of a river (What the valley and channel shape is)
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Describe 2 physical causes of flooding.
Prolonged rainfall - The ground is saturated, so rainfall can no-longer infiltrate, causing it to run-off. Relief (height of the land) - A steep relief will cause more surface run-off, meaning water gets to the river faster.
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Describe 2 human causes of flooding.
Deforestation - Cutting down trees reduces interception and encourages surface run-off. Building Construction - Impermeable materials (Tarmac and concrete) encourages surface run-off, increasing discharge quickly, causing flooding.
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What is river discharge?
The volume of water that flows in a river per second, measured in cumecs (cubic centimetres per second)
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State 2 factors which determines how much water is in the river?
Amount of rainfall - Lots of rain/ short, heavy periods mean there is more surface run off. Previous weather - after lots of rain, the soil is saturated and cannot absorb more water, causing more run-off.
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State 2 more factors which determines how much water is in the river?
Land Use - Impermeable rocks in urban areas increases surface run-off. Relief - a steeper relief causes more surface run-off. All of these decrease lag time and therefore increase discharge.
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Describe the formation of levees.
During a flood, eroded material is deposited over the floodplain. The heaviest material is dropped first, creating raised embankments called levees
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Describe the formation of floodplains.
Floodplains are created by meanders migrating over an area of land.
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Describe the formation of an ox-bow lake.
Erosion causes the outer bend of a meander to get closer, leaving a small band called the neck. The river eventually breaks through the neck (usually during a flood). Deposition then cuts off the meander, forming an ox-bow lake
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What is a waterfall?
A waterfall is where a ricer flows over an area of hard then soft rock, causing a steep drop.
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Describe the formation of a waterfall.
The softer rock is eroded faster than the hard rock, creating a step, that then becomes a steep drop. The hard rock is undercut by erosion, then collapses. At the bottom a deep plunge pool is formed.
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Describe the formation of a gorge.
A steep sided gorge is formed when a waterfall retreats (moves back up the channel) leaving the steep sides.
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Draw the formation of an ox-bow lake.
.
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Draw the formation of a waterfall.
.
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Draw the formation of a gorge.
.
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Draw the formation of a levee.
.
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What is meant by the term ‘lag time’?
Lag time is the delay between peak rainfall and peak discharge.
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Sketch and label a Hydrograph.
.
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Name a case study of a flood in a MEDC.
Boscastle, England. 16th August 2004. River: Valency.
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Describe the causes of the Boscastle flood.
Heavy rainfall: 200mm in 4 hours. Steep relief- surface run-off. Small area of woodland due to deforestation- encouraged surface run-off.
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Describe the primary impacts of the Boscastle flood.
0 deaths. Majority of people temporality left homeless. 80 properties damaged, 4 compleatly destroyed.
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Describe the secondary impacts of the Boscastle flood.
Loss of tourism meant loss of income. Businesses were closed for up to 6 months. Insurance costs rose. £2500 lost income. £500 mill. spent of repairs.
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Describe the short-term responses of the Boscastle flood.
Emergency services responded quickly. 150 people were airlifted to safety by 7 helicopters. The community centre was used for shelter and as a place to gather.
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Describe the long-term responses of the Boscastle flood.
£800 000 spent on a flood defence scheme. The river Valency was widen by 3m.
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Name a case study in a LEDC
Bangladesh and India. July and August 2007. Rivers: Brahmaputra and Ganges.
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Describe the causes of the Bangladesh flood.
Heavy rainfall - 900m in July. Melting snow from glaciers in the Himalayas. Peak discharge of both rivers happened at the same time, causing increased discharge downstream.
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Describe the primary impacts of the Bangladesh flood.
Over 2000 deaths. 25 mill. were left homeless. 44 schools destroyed. Many factories were damaged and livestock was killed. Rivers became polluted with waste and sewage.
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Describe the secondary impacts of the Bangladesh flood.
Children lost out on education. 100 000 people caught water-borne diseases. Flooded fields reduced food yield, increasing price. Farmers and factory workers because unemployed.
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Describe the short-term responses of the Bangladesh flood.
Many people couldn't evacuate and were stranded by broken transport lines. International charities and government distributed food, water and medical aid. Technical equipment like rescue boats were also sent to help those stranded.
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Describe the long-term responses of the Bangladesh flood.
International charities have funded rebuilding of homes and helped the agriculture and fishing industries. Homes have been rebuilt on stilts so they're less likely to be damaged by future floods.
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What is hard engineering?
Hard engineering strategies are man-made structures built to control the flow of rivers and reduce flooding. This includes channel straightening and dams/resivoirs.
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What is soft engineering?
Soft engineering strategies are schemes set up using knowledge of a river and it's processes to reduce the effects of flooding. This includes flood warnings and planting trees.
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Describe Channel Straightening and the advantages/disadvantages. (Hard Engineering)
The river's course is straightened out so the water movers from that area faster (Adv.), but causes more erosion downstream due to moving faster and there is more chance of downstream flooding since it is getting there faster (Dis.).
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Describe Dams/Reservoirs and the advantages/disadvantages. (Hard Engineering)
Dams are built across a river and a reservoir is a lake that forms behind. Reservoirs regulate water going into the river, can be used as drinking water or for HEP (Adv). They are very expensive, flood existing settlement & stop material moving (Dis)
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Describe Flood Warnings and the advantages/disadvantages. (Soft Engineering)
The Environment Agency warns people about floods. This reduces the impacts of flooding because people can prepare (Adv.) but it doesn't stop the flood, people may not receive the warnings and it may cause insurances to rise (Dis.)
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Describe Preparation and the advantages/disadvantages. (Soft Engineering)
Buildings are modified to reduce damage and people plan what to do in a flood. People are less likely to worry and impacts of floods are reduced (Adv.) however, it doesn't guarantee safety, gives a false sense of security and can be expensive (Dis.)
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Describe Floodplain zoning and the advantages/disadvantages. (Soft Engineering)
Restiction on where to build in regards to where is likely to be effected by a flood. Risk of flooding is reduced and so are the impacts (Adv.), however it doesn't work in areas that have already been built on or where expansion is necessary.
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Describe 'Do Nothing' and the advantages/disadvantages. (Soft Engineering)
No money is spent on management and the idea is that flooding in natural and should happen. The flooded land becomes more fertile (Adv.) but the risks and impacts of a flood aren't reduced and will a flood would causes a lot of damage.
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State a Case Study of a Reservoir.
Kielder Water, over 10 km long, located close to the Scottish border in Northumberland. Opened in 1982. Water is pumped into the river Tyne.
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Physical advantages of the area.
High Annual rainfall (1370mm). Limited loss of wildlife habitats due to rough grazing and coniferous woodlands. Base rock was impermeable volcanic rock. Large water catchment area.
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Human advantages of the area.
Few people lived in the valley, only 7 families rehoused. Little farming on the poor quality soil.
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Physical advantage of the scheme.
There were no adverse impacts due to similar water balance. It is used to fill the primary sources for the Tyne and Weir in times of drought. The dam improves flood control.
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Human advantage of the scheme.
Jobs increased and the economy of the remote area was drastically improved. Water (and land) activities attracts over a quarter of a million visitors a year. A small HEP scheme gives power to about 10000 people. Increased wildlife conservation.
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Other cards in this set

Card 2

Front

Describe 4 ways how rivers erode material.

Back

Hydraulic action- The force of the river breaks rock particles. Abrasion- Rocks scraps against the channel, wearing it away. Attrition- rocks rub together to become smaller and rounded. Solution- river water dissolved rocks e.g. chalk and limestone.

Card 3

Front

How is the outside of a meander different to the inside of a meander?

Back

Preview of the front of card 3

Card 4

Front

How is the upper course of a river different to the lower course?

Back

Preview of the front of card 4

Card 5

Front

How is the upper course of a river different to the lower course? (Continued)

Back

Preview of the front of card 5
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