Rivers

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  • Created by: Cat Gray
  • Created on: 22-03-13 18:22
Drainage baisin
the area of land drained by a river
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Catchment area
the area within the drainage baisin
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Watershed
the edge of highland surrounding a drainage basin. It marks the boundary between two drainage basins
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Source
the beggining or start of a river
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Confluence
the point at which two rivers or streams join
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Tributary
a stream or smaller river which joins a larger stream or river
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Mouth
the point where the river comes to the end, usually when entering a sea
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What is the water cycle also know as?
the hydrological cycle
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How much of the worlds water is stored in seas and oceans?
97%
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Long profile
a slice through a river from source to mouth
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How are V-shaped valleys formed?
watre flowing down steep slopes near its source causing verticle erosion
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Hydraulic action
the force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away
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Abrasion
rocks carried along by the river wear down the river bed and banks
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Attrition
rocks being carried by the river smash together and break into smaller, smoother and rounder particles
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Solution
minerals are dissolved in the water and carried along in solution
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Suspension
fine light material is carried along in the water
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Saltation
small pebbles and stones are bounced along the river bed
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Traction
large boulders and rocks are rolled along the river bed
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What are the four different river transport processes?
solution, suspension, saltation, traction
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What are the four main forms of river erosion?
hydraulic action, abrasion, attrition, solution
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When can large rocks and boulders be transported?
when energy levels are high usually near a river's source when its cource steep and its valley narrow
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When is a rivers energy levels lowest?
when velocity drops as a river enters a lake or sea (at the mouth)
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Deposition
when a river loses energy, it will drop or deposit some of the material it is carrying
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Deltas
formed when deposition occurs at a rivers mouth, when a river deposits its material faster than the sea can remove it eg Mississippi
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What do upper-course rivers feature?
steep-sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges
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What do middle-course rivers feature?
wider, shallower valleys, meanders, and oxbow lakes
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What do lower-course rivers feature?
wide flat-bottomed valleys, floodplains and deltas
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Interlocking spurs
formed as the river erodes the landscape in the upper course, it winds and bends to avoid areas of hard rock
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How are rapids and waterfalls formed?
when a river runs over alternating layers of hard and soft rock
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Meanders
as the river erodes laterally, to the right side then the left side, it forms large bends, and then horseshoe-like loops
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What happens in the inside of a bend of a meander?
the river flow is slower, material is deposited, as there is more friction
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Discharge
the water flowing in a river
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Oxbow lakes
as the horeshoe becomes tighter the ends get closer and when the river breaks through the ends join and the loop is cut off from the main channel
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What are the three types of delt?
arcuate or fan-shape, birds foot, cuspate
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Flood plain
the area around a river that is covered in times of flood, they are fertile and good for agriculture because of the rich alluvium in floodwaters
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Arcuate or fan-shaped delta
the land around the river mouth arches out into the sea and the river splits many times on the way to the sea, creating a fan effect
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Birds foot
the river splits on the way to the sea, each part http://getrevising.co.uk/revision-tests/create?st=flashcardsof the river juts out into the sea, rather like a bird's foot
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Cuspate
the land around the mouth of the river juts out arrow-like into the sea
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Steep-sided channel
a river channel surrounded by steep slopes causes fast surface run-off
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What encourages flooding?
a steep-sided channel, a lack of vegetation or woodland, drainage baisin
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A lack of vegetation or woodland
trees and plants intercept precipitation (ie they catch or drink water). If there is little vegetation in the drainage basin then surface run-off will be high
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How does a drainage baisin encourage flooding?
drainage basin, consisting of mainly impermeable rock - this will mean that water cannot percolate through the rock layer, and so will run faster over the surface
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How does a drainage baisin in an urban area encourage flooding?
these consist largely of impermeable concrete, which encourages overland flow. Drains and sewers take water quickly and directly to the river channel. Houses with sloping roofs further increase the amount of run-off
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Surface run-off
the water that runs over the surface of land when the soil is unnable to absorb it
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Name some flood managing techniques
river engineering, afforestation and planning controls to restrict urban development on floodplains
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LEDC case study
causes and effects of flooding in Mozambique (2000) + flooding in Bangladesh
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MEDC case study
causes and effects of flooding in Boscastle, UK (2004)
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Hard engineering options
damn construction, river engineering
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Soft engineering options
afforestation, planning, managed/ecological flooding
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Who prefers soft engineering and why?
environmental groups and local residents, cause little damage to the environment and do not involve the resettlement of communities
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Who prefers hard engineering and why?
governements and developers, they can generate income and profit
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LEDCs tend to use a large percentage of their water for:
agricultural (farming) use
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One way in which water is used for agriculture is called:
irrigation
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MEDCs demand more domestic use of water because:
the lifestyle includes time-saving devices which use more water – such as washing machines
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Human activities that cause drought are:
cutting trees down for fuel makes soil less able to hold water causing desertification +constructing dams to give water to farms for irrigation causing drought downstream
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Effects of drought
thirst, famine, puts pressure on resources in neighbouring countries
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Drought case study
drought in the Sahel
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Drought case study
the impact of drought in the UK (2004)
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Other cards in this set

Card 2

Front

Catchment area

Back

the area within the drainage baisin

Card 3

Front

Watershed

Back

Preview of the front of card 3

Card 4

Front

Source

Back

Preview of the front of card 4

Card 5

Front

Confluence

Back

Preview of the front of card 5
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