OCR A-Level Geography Physical Notes- Unit 1

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  • Created on: 10-05-13 11:14
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River Environments
What processes and factors are responsible for distinctive
landforms?
Slope processes and channel processes give rise to distinctive fluvial landforms. These processes are
influenced by a range of factors which vary from place to place.
Features of Erosion and/or Deposition
Features Features Both
of of
Erosion Depositio
n
Feature Info Features Info Features Info
V-shaped Upper course has Braided Main channel Meanders High velocity,
Valleys steeper valleys. Channels separates into finer load &
smaller, interlocking straight channels.
channels. Formed Near bank full
when river cannot stage these
hold load in single curves are
channel. developed.
Graded Streams adopt a Floodplain Increased discharge Ox-bow Where a bend in
stream concave, long s so river spills out. lakes the meander
profiles profile. Steeper in Increased flooding becomes steeper
headwaters. and deposition forms & eventually
floodplain with sealed off by
alluvium. deposition.
Waterfall Resistant rock over Levees Raised ridges,
s and weaker rock, parallel to edge.
Gorges undercut by Formed when
hydraulic action & flooding occurs.
abrasion. Coarse material
deposited.
Potholes Hole in base of Deltas Large amounts of
stream or river sediment carried,
formed by abrasion. entering still body of
water (sea).
Sediment deposited
in salty water.
Factors affecting these features
Rock type and structure
Slopes
Climate
Change in sea level
Processes responsible for these features
V-shaped Valleys: erosion on base, weathering and mass movement on slopes

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Graded stream profiles: erosion
Waterfalls and gorges: hydraulic action, abrasion & mass movement
Potholes: abrasion
Braided channels: deposition
Floodplains: flooding, deposition, snow melt & rain
Levees: flooding & deposition
Deltas: deposition
Meanders: erosion & deposition
Ox-bow lakes: erosion & deposition
Deposition is the load the river is carrying which is formed by erosion and weathering of surfaces
consisting of both fine and coarse materials.…read more

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Recreation & Leisure Cotswold water park- Iguazu Falls- world
windsurfing, sailing, heritage site
etc. Attracts 1,500,000
Valley of Cherwood- visitors a year
sports ground, 4 & 5* hotels near falls
botanical gardens, etc.
Water Supply Overuse= low flow Sao Paulo
4700m litres distracted
Used 8x from
Cotswold before
reaching Thames
Energy Supply Not steep enough for Itaipu: generates
HEP 12,600mw, loss of
Used for industry to forest land & plants,
create power provides 25% Brazils
demand, disrupts
travel, 25-35%
Paraguay's income.
Residential Dev.…read more

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Slope gradient: steeper= faster run-off
Vegetation: good interceptor, slow run-off
Geology: Porous- allows water in, slows down flooding; Igneous- no water in
Precipitation type: snowmelt- rapid melt= seasonal flooding
Drainage density: Greater density= shorter distance to travel
Rainfall duration and intensity: High intensity, short duration storms= flash floods
CASE STUDY
2007 floods in England
Torrential downpours which hit central and western England- worst rainfall on record in over
200yrs
More than double seasonal average
Months' worth of rainfall in day 1 (South Yorkshire), Months' worth…read more

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What are the management challenges associated with the
development of river landscapes?
Successful management requires an understanding of physical processes. Managing river landscapes
is often about balancing socio-economic and environmental needs. This requires detailed planning
and management.
CASE STUDY
Managing the Thames at Managing the flood risk:
Oxford Bangladesh
Hazard Oxford is low-lying- 2 Why is it Large areas made up of
major rivers meet impossib Ganges and Delta
Dev. Can cause conflict le to 5m above sea level
and Inc.…read more

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Prevent backflow- Inc. risk of
cholera and malaria
Loss of biodiversity- dries
out land
Decrease in flooding= less
fish, Dec. in protein source
among poor
Proposed 8km long, 25m wide
Strategies flood channel from
Thames at Binsey to
Sandford Locke
Western corridor- SSSI
Water storage areas- 4
areas
Large farmland areas
allowed to flood
Above ground reservoirs
Cold Environments
What processes and factors give cold environments their
distinctive characteristics?
The distinctive characteristics of cold environments are a result of climatic and geomorphological
processes.…read more

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Ways that ice and water shape the landscape to produce distinctive landforms
Climate & Weathering:
Plucking- ripping out material from bedrock, bottom of glaciers, Downhill pressure/drag, once
plucked it can be used for abrasion.
Abrasion- sand paper effect, material carried by glacier, more angular load-greater erosion, difficult
to observe- dig tunnels (basal cavity)
Freeze Thaw- during and after glaciation, rock fracture from pressure release, expansion and
contraction of cracks after ice melt, fractured- more likely.…read more

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Waterfalls & scree which now often covers sides of troughs. Moraines
Ribbon Lakes now lie on floor damming water forming ribbon lakes.
Moraines Gorner Glacier, Subglacial- debris carried in ice making way into crevasse-
Switzerland found at base, after steady retreat of Ice.
Medial- 2 glaciers meet lateral moraine of each in centre of
glacier.
Terminal- At stout of still or slow moving glacier, lots of
material deposited at crescent to shape mound.
Lines of loose rock fragments weathered from valley sides.…read more

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CASE STUDY
Changes in Europe's permafrost
25C Summer dropping to 2C & 6C in Winter
High elevations- flowers/Low elevations- growing
Colour attracts insects for pollination
Coniferous trees photosynthesise at low temps.
Threatens Alpine villages and ski villages with rock falls and landslides.
PACE- monitors creeping effect of climate change on stability of mountain
Permafrost exists as far South as Sierra Nevada, Spain.
Alps at 2500m in Sweden, Svalbard, Arctic found at sea level.
Too hot and mountains are too low for Permafrost.…read more

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Inupiaq rely on marine ecosystems while Gwich'in rely on Caribou herds
Area 1002- near Prudhoe Bay, reserves of oil and gas
Less than 1/10th of ANWR but crucial to Caribou and ecosystem
Oil and Gas extraction disrupt Caribou
Oil and gas- greater security on supplies cutting imports
Modern technologies used to make it less environmentally intrusive
Extraction will harm Gwich'in tribes culture and disrupt migration of wildlife
Networks will be needed e.g. pipelines, roads, etc.…read more

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MrNicecarl

THANK YOU SO MUCH!!!!

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