geography unit 1

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What is a drainage basin?
It is an area of land drained by a river and its tributaries.
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What do all systems have?
1) inputs 2) transfers 3) stores 4) outputs
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What is and input?
Things that go into them
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What are transfers?
Ways of moving something from one place to another
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What are stores?
Places where things are sorted
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What are outputs?
Things which come out at the end
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What is precipitation?
1) an input 2) any water from the sky
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Give 4 examples .
1) rain 2) hail 3) sleet 4) snow
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What is interception by vegetation?
1) A store 2) when leaves and grass catch raindrops as they fall and store them 3) It helps slow down surface run off and prevent flooding.
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What is surface run off/ overland flow?
1) A transfer 2) Water running over the surface of the ground 3) because land is either saturated or permeable
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What is infiltration ?
The downward movement of water from the surface into the soil.
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What is throughflow?
The water flows down slope/ hill through the soil. This is not the same as infiltration where the water percolates down rather than through the soil. Always shown as an angle.
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What is percolation?
The process by which water moves downwards through the soil and permeable rock. This is after infiltration.
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What is ground water flow?
This is the water stored underground. Gravity causes groundwater to flow through the rocks and soil towards the sea
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What is river discharge?
1) An output 2) water flowing away from the river
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What is evaporation?
1) An output 2) change water into water vapour.
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What is transpiration?
When plants give off water vapour
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What is condensation?
When water vapour changes to water droplets
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What is surface water?
movement of water over the ground
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What is ground water?
movement of water below the ground
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Name the parts of the water cycle in order.
1) Evaporation 2) Transpiration 3) Condensation 4) Precipitation 5) Surface Water 6) Ground water
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What does infiltration depend on ?
1) the amount and intensity of the rain 2) the amount of surface water 3) the amount of water already in the soil 4) The vegetation cover 5) the permeability of the soil
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What is the watershed?
The imaginary line which surrounds a drainage basin
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What is the source?
The starting point of the river
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What is a tributary ?
Smaller rivers which flow into a larger river
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What is a confluence?
A point where 2 rivers meet
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What is the mouth ?
Where a river enters a sea or lake
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What is attrition?
Attrition takes place when stones that are being carried downstream knocks against eachother and start to wear each other down. This knocks the edges of the stones and results in smaller, rounder sized stones further downstream.
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What is abrasion / corrosion?
The force of the moving water in the river throws the stones and other eroded particles that it is carrying against the bed and banks of the river, and this dislodges more material. It works little a piece of sand paper grinding and eroding the rocks
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What is hydraulic action?
This is when the force of the water pounds into the river bed and banks and dislodges more material. It is like a power hose.
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What is solution?
This is when weak acid ( chemicals ) in the water react with the rock and dissolves soluble minerals. It happens often in limestone materials.
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What is transportation?
When eroded material in the river is carried from place to place
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What is traction?
When heavy particles of eroded material are rolled along the river bed.
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What is saltation?
When some of the heavy particles are not held up in the flow of the river . The be bounced along the bed instead.
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What is suspension?
When the speed of the water increases, the river is unable to pick up larger particles and stones in its flow. When particles are carried along in the flow of the water and do not make contact with the river bed , they are suspended within the water.
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What is solution?
When some minerals ( like limestone) dissolves easily in water and the microscopic particles are held up in the solution of the water.
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How is a waterfall formed?
1) A layer of hard rock lies on top of a layer of soft rock 2) River flows over hard rock and erodes the soft rock 3) a step develops 4) Hydraulic action and abrasion deepen a step 5) Undercutting develops 6) Deep plunge pool under waterfall
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What happens then?
7) hard rock hangs over plunge pool 8) hard rock is too unstable , breaks + collapses 9) waterfall formed - retreating + gage formed
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When do floods happen?
When there is a temporary , extra amount of water in the river system , which causes the water in the river cahnnel to overflow , covering area of land and the surrounding flood plains that are usually dry.
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what are the 4 physical causes?
1) precipitation 2) soil and underlying rock 3) land use/ vegetation 4) steepness of drainage basin
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Explain how precipitation effects flooding.
- more rainfall over a few days - more rapidly water fills spaces in soil- ground saturated - water forced to run off into river . In droughts, rain water struggles to infiltrate into soil - ground is backed by ground.
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Explain how soil and underlying rock effects flooding.
Sandy soils are permeable and allow water to pass through quickly. Clay soils are less permeable and stop the water- causing flooding at surface and increased surface run off.
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What is the name for a permeable rock?
porous
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What is a porous rock?
Allows water to pass through with ease
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3 Examples ?
Limestone, chalk and sandstone
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What s the name for an impermeable rock?
non-porous
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What is a non-porous rock?
water does not pass through them
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3 examples?
basalt , slate and granite
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How does land use affect flooding?
Any drainage basin that has very little vegetation will be more likely to experience flooding than areas where there is much vegetation and forests. Trees interrupt water through their leaves and root systems . Water is stored not in river.
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How does the steepness of the drainage basin affect flooding?
A large drainage basin means that the water will take a long time to reach the river and is less likely to flood quickly.
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What are hard engineering strategies?
These are major alterations and changes to the river. Machinery is used to change the river and new walls and banks are built . These measures are not sustainable in long term.
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Give 6 examples.
1) Channel enlargement 2) Bridge widening 3) River straightening 4) Levees and embankments 5) Dams/ reservoirs 6) Storage areas
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Explain Channel Enlargement .
Deepening and Widening. - More space- more water capacity
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What are the disadvantages?
1) river often silts up rapidly 2) heavy machinery 3) negative impact on local ecosystems 4) Removing bottom and sides of river will increase velocity
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Explain River straightening .
remove meanders - increase velocity - water away from flood plain faster
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Explain Levees and embankment.
Water can not get over wall or levee - cannot cause damage
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What happens when a river flows naturally?
It usually deposits silt on the flood plain.
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what are dams/ reservoirs used for?
Can be used to make hydraulic power. Can be used for recreational activities.
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How are storage areas used?
Water can be pumped out of the river and stored in temporary lakes
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What are soft engineering strategies?
soft engineering is the use of ecological principles and practices to reduce erosion and achieve the stabilization and safety of shorelines and the area surrounding rivers, while enhancing habitat, improving aesthetics, and saving money.
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Name 2 strategies.
1) Land zoning 2) Afforestation
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Explain land zoning.
dividing the floodplain up into areas which experiment different degrees of flood water risk.
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What zone are there?
1) Red zone - non residential land eg golf courses ,parks , farms 2) amber zone- Car parks , sports facilities 3) Green zone - Residential housing
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Why is this effective?
it is cheap and easy to create
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What is afforestation?
Trees are planted near to the river. This means greater interception of rainwater and lower river discharge. This is a relatively low cost option, which enhances the environmental quality of the drainage basin.
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What is a meander?
A bend in the rivers course
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How is a meander formed?
On the outside of a meander the water is deeper and flows faster. The force of the water erodes the outside bend by abrasion forming a river cliff.
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What about the inside of the bend.
The water is shallower and flows slower. There is not enough energy to transport material so sand and small pebbles are deposited creating a gentle slip off slope.
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What happens as the meander get eroded on the outside of the bend?
The bend get wider. Lateral erosion on the valley floor.
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What is a river cliff?
Formed by erosion of the outside bend of a meander. This is where the water moves quickest and the river undercuts the bank because of erosion , corrosion ( abrasion) and hydraulic action.
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What is a Slip of slope?
Formed on the inside of the bend where the river flows slowly and deposition takes place. This is also the shallow part of the river.
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What is a levee?
A naturally raised bank of alluvium at the side of a river.
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How is it formed?
- River floods onto flood plain , speed reduced and slit deposited - Coarse heavy material is deposited first followed by finer material - more material = build up into large embarkments = levees.
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What is a flood plain?
This is a flat area over which a river meanders mainly in its lower course.
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How is it formed?
1) Erosion and deposition 2) as river meanders migrate down stream they erode sideways and make the flood plain wider. 3) When the river floods it deposits silt and alluvium onto the valley floors which makes floodplains fertile and desirable.
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Name a case study outside the uk for river flooding.
Mississippi river flood 1993
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How was it caused?
Rapid snow melt, heavy rain April 1993, rapid run off, flash floods
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How was it managed?
1) 100 + dams built on the ohio river 2) Strengthened and heightened levees 15m high 3000km long 3) Straightened river - 1750km
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Name a case study inside the uk for river flooding.
River Derwent, England March 1999
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How was it caused ?
1) 250mm rain over 12 days - ground saturated 2) Removal of peat 3) houses built on floodplain less infiltration more runoff
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What is swash?
Water which rushes up the beach .
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What is back wash ?
Waves wash up shore and loses momentum and energy is transferred back to the sea.
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What is a constructive wave?
It builds landscape . It is gently flat and low( 1m). energy limited on a few waves per min ( 6-9)
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What is a destructive wave?
more energy , steep ( 3-4m), close together , more waves per min ( 15) strong back wash pull material back into the sea creating steep beaches.
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What is a cliff?
a vertical rock face along the coast.
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What is a wave cut platform?
A narrow flat area often seen at the base of a cliff. Caused by erosion. 1) notch formed in base cuz of corrosion +HA - WEAKNESS. 2) Upper cliff undercut + collapses
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how is a stack made?
1)wave cut notch enlarges=cave 2)+erosion through headland=arch 3)waves+weathering= undermine upper portion= cannot hold weight= collapses= stack
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How is a beach formed?
DEPOSITION. 1)Constructive waves push material like sand + shingle on coast 2) material builds up 3) blown inshore = beach
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How is a spit formed?
1)waves lift eroded material by longshoredrift 2) bend in coastline= deposition 3)material buids= sea ridge 4) mud+marsh trapped behind spit 5)spit reaches deep water+ wind + sea currents = curve end = hooked spit
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How does RESIDENTIAL activity effect the human activity on the coast?
Sea View = :) people want to see sea from house = pressure onlocal land owners+ coucils to develop houese / hotels
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How does TOURISM activity effect the human activity on the coast?
beach holiday= :)= conflict with residential + industry. Tourism = Money BUT hard to sustain
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How does TRANSPORT activity effect the human activity on the coast?
Road + Railways = follow coastlines = money to maintain
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Why do we need coastal defences?
3.2billion ppl live within 200km of sea. Global warming= more important for low lying coastal regions
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