Geography- paper 1

• Definition of natural hazard

  Types of natural hazards

  Factors affecting hazard risk

  -Extreme natural events that can cause loss of life, extreme damage to property and disrupt human activities.

  -E.g. Tropical storms, floods, tornadoes, droughts

  -Population, amount of buildings, protection done to buildings
• Plate movements

  Collision- two plates collide into each other (if two continental plates collide they buckle up to from mountains).

  Destructive- oceanic (which is denser) subducts under the continental plate forcing mantle to rise up as magma through volcanoes.

  Conservative- two plates slide past each other building up friction and causing pressure which is released from the focus to the epicentre as seismic waves to cause earthquakes.

  Constructive- two plates move away from each other creating an earthquake and allowing magma to rise and cool to from shield volcanoes.
• Plate tectonic theory

  -These plates move due to the circular movement of convectional currents. Magma is heated up from the outer core and then sinks back down as it gets cooled by the crust.
• Nepal Earthquake 2015


  Primary Effect-$5billion cost of damage

  Secondary effect-triggered avalanche that left 250 missing people

  Immediate response-search and rescue teams, water and medical support from UK, India and China

  Long term response-stricter controls on buildings
• Japan Earthquake


  Effect: cost of damage was $235 billion and 4 million left without electricity

  Responses:50,0000 people evacuated and power was restored
• Reasons why people still live in areas at risk from tectonic hazards

  -Use of geothermal energy from volcanoes

  -volcanic environment provides nutrients for soil for growth

  -can't afford to relocate or area may be worth value for them

  -takes time for another hazard to strike
• Earthquake Aware by:

  Monitoring-use seismometer to record ground shaking

  Prediction-use historical records of earthquakes at plate margins

  Protection-reinforce buildings with concrete columns and steel frames

  Planning-have earthquake drills
• Volcanic aware by:

  Monitoring-record heat changes from satellites

  Prediction-use previous records

  Protection-create path to divert lava away from vulnerable buildings

  Planning-find out safe routes around the volcano
• Atmospheric circulation:


  Hot air rises from the equator (low pressure) when it gets high it cools and sinks back down towards earth(high pressure).

  
• tropical storm Cause:

  Ocean surface water reach ≥27°C due to solar heating, the warm vapour rises, causing a low pressure belt. As the air rises quickly more warm moist air spirals up creating strong winds before cooling into cumulonimbus clouds that give off precipitation (causing a high pressure belt).

  
  

  +With climate change the magnitude and frequency of tropical storms will increase.
• Typhoon Haiyan 2013

  Primary effect- power supplies cut off due to collapsed buildings

  Secondary effect- looting and violence broke out

  Immediate response- Red Cross gave food, water and search and rescue teams

  Long term response- rice farming re-established to provide income
• Tropical storm aware

  Monitoring- watch satellite data of cumulonimbus clouds

  Prediction- warning system

  Protection- drains to prevent flooding

  Planning- community awareness programme for people to understand what to do
• Sommerset Flooding

  Causes: river not dredged for 20 years, hills trapped rainwater inside the city

  Impacts: 16 farms evacuated(soc), railways closed(eco), huge amounts of debris had to be cleared(env)

  Response: river was dredged, drains built, used sandbags as temporary flood defences
• Evidence of climate change

  -thin tree rings shows cold and dry years while thick tree rings show warm and wet years

  -number of co2 in ice cores

  -rate of glaciers retreating from past data
• Causes of climate change:

  -Sunspots are eruptions on the sun's surface that increase temperature and brightness towards the earth.

  -Volcanic eruptions release ash that reflect the sun's rays causing a volcanic winter. In the long run, Co2 that is emitted is added onto the greenhouse gasses that trap heat inside.

  -Elliptical movement, when the earth is further away from the sun causing our planet to cool vice versa

  -agricultural fertilisers release nitrous oxide

  -livestock farming releases methane

  -deforestation releases co2
• Adapting to climate change


  _Farming problem-extreme weather events, change in pattern of rainfall and temperature+solution-new irrigation system, changing planting dates_Water supply Prob-over 1/5 world's population rely on glaciers that feed water to rivers, which is reducing+sol-collect water and freeze water in the winter through canals and embankments. To be melted in the summer to provide water for locals and crops_Sea level rise pro-costal erosion increases, more areas prone to storm surges+sol-build homes on stilts, construction of sea walls with sandbags or coastal mangrove forests
• Mitigation(reducing the risk) of climate change

  -Catch carbon from industries and inject them into the ground or under the reservoir

  -afforestation means that more trees absorb co2 from photosynthesis

  -use alternative energy: solar, hydro, wind
• NutrientsCycle

  The weathering (breaking down) of rocks provide nutrients for the soil. The roots of the plants take up the nutrients for growth to be used as biomass. When leaves fall off (litter), they are washed away by rainfall or decomposed (broken down) to provide nutrients in the soil. Sometimes nutrients from the soil may also be washed away (leached).
• Tropical Rainforest

  Most nutrients are found at the surface. Dead leaves decompose rapidly due to high temperatures. Trees and plants have shallow roots to absorb the nutrients. Heavy rainfall can quickly dissolve and carry away nutrients by leaching. It leaves behind a infertile soil.
• Tropical Rainforests' formation

  Emergent- very sunny because its the very top. only the tallest trees reach this level.

  Canopy- much of the rain is stopped by the thick leaves. Most grow to this height.

  Under canopy- many vines, dense vegetation, not much sunlight as the canopy trees are blocking it.

  Shrub layer- dark, damp, full of many dead leaves, twigs and dead plants
• Forest Adaptions

  Buttress roots- massive ridge to help support the base of tall trees and help transport water.

  Drip tip- allows water to drip off the leaves and prevent algae growing which blocks the sunlight.

  Lianas- vines rooted in the soil and uses trees to get high enough to receive sunlight
• Forest threats

  -logging for resources or to create land for mining

  -cutting down trees for livestock farming or buildings
• Animal in the forests adaptions

  -camouflage like green eyed tree frog blend into the environment to protect against predators

  -limited diet like the toucan eating fruits that other animals are unable to access
• Forest Impacts

  -increase climate change due to less carbon being captured

  -loss of 25% of all plant species and 600 animal species

  -development for mining but pollutes water sources

  -soli easily erodes away by wind and rain
• Forest managements


  -selective logging and replanting

  -Ecotourist

  -International Agreements
• Polar environments:

  -soil is permanently frozen

  -temperature fall between -50°c

  -precipitation levels are very low

  -animals have thick fur, insulating layer of fat, black pads to absorb sunshine

  -some mosses and lichens grow on the fringes of ice

  -water drains through the soil, washing away nutrients
• Tundra environments

  -temperatures fall to -20°c

  -low growing plants like bushes

  -soil is frozen but melts in the summer

  -many animals like the Artic fox and hare live there

  -birds and insects are here in the summer

  -precipitation is mainly snow and can fall in high levels near coast
• Opportunities in Svalbard

  -fishing from 150 species

  -tourism provides 300 jobs

  -energy development like Iceland (on a constructive margin)using geothermal energy
• Challenges in Svalbard

  -inaccessibility, difficult to transport though most people use snowmobiles. e.g. 50km of raod only in Longyearbyen

  -provision of buildings, constructing roads on top of gravel, permafrost can provide solid foundation but need to be protected from melting

  -extreme temperatures make it dangerous to work outside and makes outdoor work slow and difficult with 2 pairs of gloves and layers of jumpers
• River process

  Tributary- a river which joins a larger river

  Mouth- where the river flows into the sea/lake

  Source- The up land area where the river begins

  Watershed- ridge of high land dividing one drainage basin from another

  Confluence- the point at which two rivers join

  Drainage basin- area which is drained by its river and its tributaries
• Erosion

  Hydraulic action-force of water hitting against the bed and banks wears away the loosened material, making the river wider and deeper.

  Attrition-material carried by the river bump into each other and are smoothened and broken down into smaller particles.

  Abrasion-The bed and banks and worn down by the river's load being thrown at them

  Solution-acidic water erodes of dissolves rocks.
• Transportation

  Traction-large boulders and pebbles roll along the river bed.

  Saltation-small stones, pebbles and stilt bounce along the river bed.

  Suspension-fine materials are carried by the river

  Solution-dissolved minerals are carried within the river
• Interlocking spurs(upper course)


  Highest vertical erosion. The river cuts down the into the valley. If there are areas of hard rock, which are harder to erode, the river will bend around it.
• Waterfalls (upper course)


  Soft rock blow the hard rock erodes through abrasion and hydraulic action because the soft rock is less resistant. Due to repeated erosion, an undercut in soft rock creates the overhang in the hard rock. Overhang collapses into plunge pool deepening the bank. Over many centuries, the waterfall may retreat to form a gorge of recession.
• Ox bow lakes (middle course)

  The river meanders. The fastest current being on the outer bend uses hydraulic action to erode the neck until a thin piece of land separates two meanders. The river floods and erodes through the thin meander neck. the river now takes a quicker straight route. Materials are deposited at the bends to create a ox bow lake.
• Floodplain and levees (lower course)

  The narrow valley is widened as the river begins to erode sideways. The meanders create a wide flat valley floor which is the floodplain. When the river floods after heavy rain, sediments in the water spills outside the banks. The finer material is carried further and is deposited as the water loses energy and the floods recede. As flooding is repeated over the years, layers of sediments build up completing the formation levees next to the channels.
• Causes of floods:

  Short lag time and high peak

  -small basins often lead to rapid water transfer

  -steep slopes lead to rapid water transfer

  -urbanization(impermeable rocks)encourages rapid water transfer

  (long lag time and low peak means water transfer is slowed down by forestry, gentle slopes, large basins)
• Dams and reservoirs

  Cost-algae collected behind deoxygenated the water for sea animals and causes distress for people who live in the area

  Benefit-provides hydroelectric power and promotes new habitats
• Straitening meanders

  Cost-expensive

  Benefit-easier navigation for trade
• Embankments


  cost-prone to erosion due to increase in sedimentation

  benefit-cost of building is low