A-Level Geography Revision notes 2015

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Contents World Development .............................................................................................................................. 2

Ecosystems ............................................................................................................................................ 4

Urban Profiles ........................................................................................................................................ 6

Soils ...................................................................................................................................................... 10

Natural Hazards .................................................................................................................................. 12

Tourism ................................................................................................................................................ 17

Environmental Hazards ...................................................................................................................... 19

River Profiles........................................................................................................................................ 20

River Processes and Management ................................................................................................... 22

Population ............................................................................................................................................ 24

Introduction to Weather and Climate .............................................................................................. 27

Weather Conditions ............................................................................................................................ 32

Coastal Processes ............................................................................................................................... 34

Deltas, Estuaries and Changes to Coastal Areas ........................................................................... 37

Agriculture ........................................................................................................................................... 39

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World Development

Indicators of development

Gross Domestic Product (GDP): This is the value of all goods and services produced within a country. It is

usually measured in US$ and calculated per capita. This makes comparisons between different countries easier.

Main advantage: universally understood.

Main disadvantage: hides inequalities within a country.

Infant mortality: this is the number of infants that die prematurely.

Main advantage: Indicates quality of health care, water quality, food supply and clearly identifies a problem in

need of addressing.

Main disadvantage: Hard to get an accurate figure as many births in the less developed countries would be un-

registered.

Remember: every indicator has weaknesses. It may be worth using a number of indicators like:

Human development index: gives countries a score between 0 and 1 for wealth, health and education. By

looking at previous placing and position on GDP tables, countries can evaluate their performances.

A divided world: in our world there are huge discrepancies in wealth, resources, standards of living. These can

be explained by:

Historical factors - coal, colonialism, slavery.

Economic factors - Debt, trade, corruption, the multiplier.

Environmental factors - natural disasters, resources.

Differences within the developing world: Do not group the developing world as one. There are differences

within it:

Oil rich countries - use wealth from oil to invest in other industries, health, sanitation and education.

Newly industrialised countries - are increasing manufacturing and exports. Firstly they produced more of their

own goods so imported less then they targeted areas in the world export market like computers and televisions.

Reducing inequalities

Debt: the possibility that developing world countries will have a lot of their debt written off is excellent but there

has been criticism of the lack of actual actions since.

Aid: it is not possible to simply give aid to a country as easy as it may sound. You must consider the

consequences of that action. Not all aid is given as a freebee - there are often strings attached.

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Bi-lateral aid: is when one country gives directly to another.

Advantage - The recipient country can get a substantial sum of money to invest in their country in whatever they

choose.

Disadvantage - Can be used to set up exploitative trade deals. For example the UK insists that several of the

countries we give aid to purchase our arms.

Multi-lateral aid: is that which is given to several countries from an. international organisation like the World

Bank.

Advantage - Can lead to the establishment of stable industry. For example India's dairy industry that supplies

most of the country was set up using powdered milk donations from the European Union.

Disadvantage - Debt repayments can massively outweigh any aid received.

There are non-governmental organisations that we refer to as charities. These try to direct the money

generated by charity at the needs of the poor, local communities or environment.

Advantage - More responsive to the immediate needs of the population. Work at a smaller scale using technology

more appropriate to the skills and needs of the locals.

Disadvantage - Unless they can have a greater influence on the policy makers then they will only ever provide

'stop-gap' measures.

Appropriate technology: This is where the local industry is geared to the needs and skills of the local people

and environment. It provides cheap and useful products. Is seen as a way of increasing standard of living,

employment, industry, allowing local people to make the decisions and being relatively kind to the environment.

E.g. separate projects in Kenya make roofing tiles and cooking stoves.

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Ecosystems

Abiotic Non-living components of the ecosystem (water, rock, air, sediments).

Autotrophs (producers) Organisms that can convert energy from the sun by photosynthesis.

Biotic Living components of the ecosystem.

Calcification Calcium accumulation in the soil as a result of low rainfall.

Carnivores Meat eaters.

Cheluviation Iron and aluminium sesquioxides removed by chelating agents.

Climatic climax Final stage in an ecosystem reached by vegetation.

Community All species found in an ecosystem.

Detritivores Decomposers.

Herbivores Plant eaters.

Heterotrophs

(consumers)

Feed on other organisms.

Illuviation Material deposited in lower soil horizons.

Leaching Material that is soluble moved downwards through the soil by solution.

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Lessivage Removal of fine clay particles from soil.

Net Primary

Productivity (NPP)

Energy made available by plants for animals.

Plagio climax Plant community unable to reach climatic climax due to human influence.

Podsolisation Intensive leaching.

Primary productivity Productivity of plants only.

Salinisation Soluble salts moved upwards through the soil as a result of capillary action.

Secondary Productivity - productivity of animals.

Sere A group of species, found as an ecosystem progresses towards climatic climax.

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Urban Profiles

Urbanisation

An urban area is a city or town.

Urbanisation: The process whereby rural areas (countryside) are becoming urban.

Reasons for growth

1. The developed world

Reasons for growth of most cities in the UK would include:

a. The industrial revolution.

b. The multiplier effect.

c. Continued growth as businesses and retail compete for areas close to the CBD and, slum clearance and the

building of high-rise developments increases population densities.

d. Most recently, the growth in car ownership, improvements in road networks and the congested nature of many

city centres has led to counter-urbanisation.

2. The developing world

It is important that you understand the reasons behind the rapid population growth.

There are two main reasons:

a. High natural growth rates.

b. Rural to urban migration.

Urban models

Models are used to simplify reality and help us understand what is usually a whole range of complex processes.

It is often useful to compare towns or cities to different models.

You should also be able to draw, explain and evaluate the models of Burgess, Hoyt and the developing

world city.

The main criticisms are that they do not take into account physical landscape and that land-uses are not as clear-

cut as the models make out.

They do, however, simplify a complex set of processes and act as a point of reference.

Urban hierarchies

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Rank size rule: This simply states that in any country, you have one very large city. The second largest is half

the size of the first, the third largest is a third of the size of the first; the fourth largest is a quarter of the size of

the largest then a sixth then a seventh and so on.

A primate city: A city that has more than twice the population of the next biggest city.

Central place theory tells us that if there is an even distribution of population, all with equal money and

transport opportunities, and the land is flat and featureless, then settlements will follow a distribution pattern

according to size. It introduces:

1. Threshold: The minimum number of people needed to support a service.

2. Range: The maximum distance people are prepared to travel to purchase a good or service.

Urban problems

More developed world

Any city in the developed world will face considerable problems. These could include:

1. Inequality. Inequalities exist in all cities in the developed world. The most deprived groups can often be found

in old inner city areas. These areas are often typified by:

2. High levels of unemployment and a lack of employment opportunities.

3. Poor household amenities.

4. Air, water and land pollution and derelict land.

5. High social problems such as alcoholism, drug abuse and crime.

6. Greater frequency of health problems.

Remember: there are positive aspects, as many people see inner cities as desirable place.

Cities will also face problems of traffic congestion and a declining CBD.

Urban solutions

There have been a number of policies and initiatives that have had the overall objective of regenerating urban

areas. In the past twenty years, these have changed frequently, but have included Urban Development

Corporations and more recently, schemes where councils have to bid for various sources of money. One of

those sources is lottery money.

The UDC in Bristol had three main successes:

1. The building of a major new road link.

2. Attracting new industry providing over 4000 new jobs.

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3. Significant housing development much of which was bought by first time buyers.

However, amongst its failures were:

1. It pursued many large flagship proposals that never happened.

2. During recession, unemployment in UDC areas went up to 25% as opposed to 5%, the city average.

3. Jobs were low skilled and poorly paid.

Another attempt to improve the urban environment has been Bristol's Harbour-side regeneration.

Bristol city council put together a regeneration bid and successfully gained £41 million from the lottery and £21

million from English partnerships.

Successes include:

1. Over £500 million pounds of inward investment. Over 3000 new jobs.

2. A mixed commercial environment that includes café bars, restaurants, cinemas, shops.

3. Residential developments providing much needed housing.

Failures include:

1. Concerns about how the area would fare during recession.

2. New houses are very expensive.

3. Less developed world.

The developing world cities are suffering many very serious problems. These are a consequence of the rapid

population growth, a lack of capital to invest and a non-existent, very poor and/or outdated infrastructure.

Problems in developing world cities include:

1. Collapsing infrastructure.

2. Increasing levels of pollution.

3. A polluted water supply.

4. Inadequate housing and services.

5. A lack of employment.

Solutions:

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Solutions to any problem are made more difficult by the lack of available resources and the sheer scale of the

problems faced. Below are some examples of different policies:

1. Site and service schemes.

2. Rehabilitation.

3. Housing developments.

4. Sewage rehabilitation.

Finally, you need to know about the influence of urbanisation on the rural environment.

Counter-urbanisation: The process by which people and businesses are leaving the urban areas to relocate in

smaller towns or rural villages.

Reasons for counter-urbanisation

Environmental and social problems with inner cities pushed people away from urban areas. At the same time,

more rural areas were seen as peaceful, unpolluted, offering greater space and the community spirit that was

lacking in inner city areas.

Improvements in rural transport infrastructures and increased car ownership allowed a greater freedom of choice

when choosing where to live.

Counter urbanisation has had a major impact on rural villages and communities.

Amongst these impacts are:

1. House prices can be pushed.

2. Public transport goes into decline.

3. Traditional rural services start to close.

4. Shops and services change to meet the needs of the new population.

5. Traffic congestion increases.

You should have a case study of a village that has been affected by counter-urbanisation.

In addition the urban area will affect the land-use particularly in the rural urban fringe.

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Soils

Regolith Weathering of parent material to give a layer of loose broken rock.

Parent material The supply of minerals comes from underlying rock, which has different rates of

weathering. It controls depth, texture, drainage, and quality of the soil.

Topography The relief of land.

Biota Organisms - Plants and bacteria, fungi, and animals all interact in the nutrient

cycle.

Peds Individual soil particles.

Soil texture How fine or course the mineral matter is in the soil.

Soil nutrients (bases) Chemical elements in the soil that come from rainwater, fertilizer, parent rock,

decaying organic matter and clay.

Soil moisture Level of moisture in the soil - important because it influences upward and

downward movement of nutrients and water in the soil.

Translocation Includes numerous processes but is primarily the downward movement of water

or materials in soil.

Leaching Where soluble material is removed in solution.

Cheluviation When iron and aluminium sesquioxides are removed due to chelating agents.

Illuviation Material re-deposited in the lower horizons.

Zonal soils Are classified on a global scale and have climate as the major determining

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factor. They are mature, have distinct profiles and clear horizons.

Azonal soils More recent than zonal soils and soil forming processes have not been in

operation for long. Horizons are unclear and they are not linked with climate

and vegetation.

Intrazonal soils Soils found within the climate belt.

Calcomorphic/calcareous

soils Develop on limestone.

Hydromorphic soils Water content is always high.

Halomorphic soils Saline due to high salt level.

Podsol Develops if precipitation exceeds evapotranspiration.

Podsolisation Intensive leaching.

Brown earths Moderately or well-drained soils, found where precipitation exceeds potential

evapotranspiration, and particles move downward through the soil.

Lessivage Removal of fine clay particles from soil.

Salinisation Soluble salts moved upwards through the soil as a result of capillary action.

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Natural Hazards

Earth's Structure

Consists of a thin outer layer, the crust.

The mantle is composed mainly of silicate rocks, which contain a lot of magnesium and iron. This is a much

thicker part of the earth.

The mantle contains many minerals, particularly iron and nickel.

In the temperatures can reach 5000 degrees Celsius, which generate convection currents.

The core is in the centre of the earth.

Natural Hazards

Physical hazards include events such as; earthquakes, volcanic explosions, flooding, drought, tropical storms and

landslides.

Remember that some of these may trigger other hazards such as tidal waves following earthquakes.

In order for a physical event or process, such as an earthquake to be hazardous there must be the potential for

some loss of life.

It is generally felt that that the less developed a country (LEDC) is the more damage, both economically and in

terms of loss of life the hazard causes.

The impact of a hazard can be increased by human activity.

Areas vulnerable to tectonic activity are usually found on or near to plate boundaries

Tectonic Processes

The location of continents today of far removed from what it was millions of years ago, when it is believed that

all continents were joined to one land mass.

Plate movement is either towards, away, or alongside adjacent plates.

Plate movement can be one of three types:

1. Convergent (destructive or collision) - Towards each other. For example: The Indian Plate and Eurasian Plate

created the Himalayas.

2. Divergent - Away from each other. For example: North American plate moving away from the Eurasian plate

resulting in the mid-Atlantic ridge.

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3. Transform or transcurrent - Alongside each other. For example: Earthquakes such as those linked with the San

Andreas Fault.

Earthquakes

Earthquakes occur because of a slow build-up of pressure in the earth's rocks, which is quickly released.

Primary Hazards are hazards due directly to the earthquake itself, and consist of ground movement and shaking.

Earthquakes emit body waves (travel through the earth) and surface waves. It is surface waves that cause most

damage as they impact on what is on the surface of the earth

Secondary Hazards are indirect hazards that may result from an earthquake:

Soil Liquefaction - Solid material changed into a liquid state. Damages building foundations, resulting in them

sinking.

Landslides - Often as a result of the ground shaking, even if a slope is gentle. Cause burial of people and overrun

buildings.

Tsunami (tidal waves) - If the focus of the quake is beneath the sea, tsunami can occur. Ninety percent occur in

the Pacific basin. The more movement of the sea floor and the shallower the focus the larger the wave that is

created.

Volcanoes

Volcanoes occur when magma from the earth's interior is able to make its way to the surface, via a vent.

The shapes of volcanoes that you should be able to recall are:

1. Fissure: Very gentle slope, found at diverging ocean plates, basaltic lava, can flow over large distances.

2. Basic / Shield: Have gentle slopes, steeper than fissure due to repeated explosions and subsequent build-up of

basalt based lava. (Mauna Loa Hawaii)

3. Cone: Symmetrical in shape, A acid where thick viscous lava, rapidly cools B) Ash / Cinder.

4. Composite: Very large old volcanoes. Both ash and lava are deposited (Mt. St. Helens)

5. Crater / Caldera: Form when a very violent eruption occurs after a build-up of gas beneath the volcano. Can

destroy the magma chamber leaving a large crater.

Types of lava Flow

This ranges from being extremely thick and viscous, to highly fluid. The amount of pyroclastic material also

varies. The two types are:

Aa flow - This is a few metres thick, a mix of uneven shaped, sharp edged ash and cinder blocks. It is unstable.

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Pahoehoe flow - Is fluid rather than viscous, but does not move quickly. Often the surface layer is static whilst

flow continues beneath.

Tropical Cyclones

Called by a variety of names: Hurricanes, Typhoons, Cyclones, Willy Willies

Tropical cyclones are generated over the Atlantic and Pacific oceans and are most common in autumn when

ocean temperatures are at their highest. There is some evidence to suggest that their frequency and severity is

increasing as a result of global warming.

Several basic conditions are necessary for hurricane formation:

1. Warm oceans with surface temperatures in excess of 27 degrees, and a deep layer of water to 60m

2. A location between 5degrees north and south of the equator. (Without this the coreolis force is not sufficient to

create the spinning motion characteristics of hurricanes.

3. Relatively stable and uniform atmospheric conditions of temperature, humidity and pressure. In the upper

troposphere air drawn in at lower altitudes must be able to escape.

4. Relative humidity of over 60% to provide sufficient energy to power the hurricane.

5. Little change of horizontal wind with height.

6. Existing cyclonic spinning of winds in the lower troposphere.

Tornadoes

Most tornado activity (70%) is found in the Great Plains of the USA. They form as a result of intensive convective

rainfall systems and are highly unpredictable.

The two meeting air masses are conditionally unstable.

Low level air has a relative humidity of over 65%.

A low level southerly jet stream exists in the humid air.

Mass Movements:

This is where land movement at a range of speeds results in destruction of property and/or loss of life. It is often

triggered by human activity. In its broadest sense it is the movement down slope of any weathered material

(regolith) under the influence of gravity.

The type of movement that occurs is influenced by:

1. Angle of slope (steeper is faster)

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2. Nature of regolith

3. Amount and type of vegetation

4. Water

5. Type and structure of rock

6. Human activity

7. Climate

Managing Hazards

Despite their apparent unpredictable nature, attempts have been made to control and influence the amount of

damage a hazard causes. Success varies due to issues such as development, frequency and perception.

There is a general belief that often individuals do not perceive themselves to be living in a hazardous area (take

Los Angeles, for example), and that it takes experience of a hazard to appreciate the danger.

This then subsides as the time since the hazard increases. In some cases, the advantages of an area may far

outweigh the potential disadvantages of the hazard (good fertile soils, favourable climate) and in the case of

technologically advanced countries the population may believe they have the technology to manage the hazard.

Hazard Impact:

Obviously this varies depending on the scale, frequency and vulnerability of the population. It is closely tied to

wealth, education, health, population and technological advances. (See earlier work on impacts of hazards).

Hazard Prediction:

This is highly complicated and its usefulness is the subject of debate. The main areas covered include forecasting

and warning in an attempt to minimise the impact. In the USA hurricane warning systems exist, satellite

monitoring equipment, as do posters TV and radio broadcasts informing people of action to take in the event of a

hurricane. Seismographs monitor tectonic activity in an attempt to find clues to a large quake.

Hazard Prevention:

Most work regard reducing the impacts of hazards is concentrated in this area as it is considered the most direct

and cost effective.

The aim is to reduce the potential impact of hazards by ensuring people are fully prepared should they occur.

Hazard prevention exists in a number of ways:

Cities in earthquake zones often use training and education, to ensure that all citizens know what to do in an

earthquake situation.

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Building Restrictions and Land Use planning - This is far more commonplace in MEDC's where there is a lower

density of population and the money available to enforce such codes.

Buildings can be restricted in height, have to conform to a certain design to ensure they have the greatest

chance of remaining intact in the event of a hazard.

Problems exist in LEDC's such as the Philippines where housing is vulnerable, due to material being salvaged

from homes destroyed in a typhoon in order to rebuild others. There is currently a move towards educating the

public on low-cost typhoon resistant housing.

Aid - Often the most contentious issues regards preventing hazards. LEDC's are eager to limit short-term hand-

outs, such as clothes, money, food, and focus on long-term measures that they believe can help a country

become more self-dependant and learn to cope with the impacts of hazards for themselves.

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Tourism

There are three mains sections to this topic...

1. Where are the tourism growth regions?

The biggest tourist destinations are more developed countries. France and the USA the largest two. These have

huge populations either within their countries or in bordering countries. They also have established reputations

and services.

Significantly the developing world is experiencing the greatest growth as long haul flights mean people can

explore further a field and Governments - See tourism as an essential source of foreign currency.

2. Why has there been such a growth?

More holidays - paid holidays increased

A smaller world - faster travel time increase tourism

Development - Governments promote tourism as it can benefit their economy

Elderly - Health care and pensions has meant that people are living longer

Society - Holidays are a normal part of Western society

Income - People are earning more than ever before and prices are relatively cheaper

Communication - ICT makes booking holidays easier and cheaper

3. What are the costs and benefits of tourism?

Factor: Developed world: Developing world:

Environmental Positive - Listed buildings

have been reclaimed on

Bristol's harbour-side and

sympathetically restored.

Negative - Snowdonia

national park has serious

problems with soil erosion

due to tourist.

Positive - Operation

campfire in Zimbabwe has

helped manage the

indigenous animals,

reducing soil erosion and

increasing land available for

agriculture.

Negative - In Goa mass

tourism has bought about

pollution of the beaches.

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Economic Positive - Regeneration of

Bristol's harbour-side

provides jobs.

Negative - There are

some doubts about how

Bristol's new developments

would survive a recession.

Positive - Operation

Campfire has been very

successful in earning

foreign currency which it

injects back into the local

economy

Negative - Mass tourism in

Goa has seen the closure of

traditional farming and

fishing industries.

Cultural Positive - Bristol's

harbour-side provide a new

and varied cultural

environment.

Negative - Question

marks about the number of

bars involved in the

development at Bristol and

the related problems with

alcohol.

Positive - Operation

campfire has meant locals

are once again earning

their living from game.

Negative - Goans

complain that tourism has

bought with it an influx of

drugs, prostitution and HIV.

4. How can tourism be used to regenerate a deprived region?

Provides jobs for a broad cross-section.

Stimulates other parts of the economy.

Improves derelict areas.

Provides facilities for locals and tourist alike.

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Environmental Hazards

Acid rain The increase in the acidity of rainfall as a result of pollution.

Condensation nuclei Particles found in the atmosphere, which encourage condensation, by attracting water.

Global warming Un-natural increase in temperature of the earth's atmosphere, due to pollution.

Greenhouse effect Natural warming of the atmosphere.

Insolation Short wave radiation from the sun.

Ozone layer Layer in the stratosphere where ozone molecules are concentrated.

Precipitation Moisture from the atmosphere in its variety of forms.

Stratosphere Layer found in the atmosphere above the troposphere.

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River Profiles

Attrition Boulders collide with one another as they move down the river, and can break into

smaller pieces. Over time rocks become more rounded in appearance.

Baseflow Water moving slowly through the ground.

Base level

The lowest point to which erosion by running water can occur.

Bedload Can be either exogenetic or endogenetic, and moves by sliding, saltating, or rolling.

Climatic change Glaciations and changes in rainfall.

Corrasion When a river picks up material and then rubs it against its bed and banks. Erosion

occurs by the process of abrasion. Most effective during times of flood. Main method of

both vertical and horizontal erosion.

Deltas River sediment deposited as a river enters lake, lagoon or ocean.

Discharge Volume of water flowing in a river at a particular point, during a particular period of

time.

Dissolved load Held in solution and can come from erosion, pollution, mineral springs and chemical

weathering.

Drainage basin Area of land that is drained by a river.

Drainage density Found by dividing total length of all streams in a basin (L) by its area (A).

Estuaries Drowned lower part of a river, as it enters the sea.

Evapotranspiration Water lost from vegetation via both evaporation and transpiration.

Groundwater Water held in the ground.

Hydraulic action Force of water that hits river banks, and then pushes water into cracks. Air becomes

compressed, pressure increased and the riverbank may, in time collapse.

Interception This is when plants prevent some rainfall from directly reaching the ground, for

example, water on leaves.

Infiltration Where water slowly soaks into the soil from the ground.

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Lag time Length of time between peak rainfall and peak discharge.

Overland flow Water flowing overland, often as a result of land being saturated.

Percolation Water in the soil does not remain there but moves down slowly into the lower layers of

soil and rock.

Potential

evapotranspiration

The amount of water that could be lost by evapotranspiration.

Regime Changes in the flow of a river throughout that occur with different seasons.

Saltation Pebbles, sand and gravel are lifted up by the current and bounced along the bed.

Solution/corrosion A continual process, which is as a result of the chemical composition of the water.

Storm hydrograph Graphs that show how a drainage basin responds to a period of rainfall.

Suspended sediment

load

Carried with the body of the current.

Suspension Very small particles of clay and silt are carried in suspension.

Tectonic change Where land is uplifted after plate movement or volcanic activity.

Traction Larger boulders rolling or sliding along the riverbed. Only experienced in times of great

flood.

Transpiration Loss of water from plants.

Throughflow Where water moves downwards through layers of soil.

Watershed Dividing line between drainage basins (usually higher ground).

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River Processes and Management

Attrition Boulders collide with one another as they move down the river, and can break into

smaller pieces. Over time rocks become more rounded in appearance.

Baseflow Water moving slowly through the ground.

Base level

The lowest point to which erosion by running water can occur.

Bedload Can be either exogenetic or endogenetic, and moves by sliding, saltating, or rolling.

Climatic change Glaciations and changes in rainfall.

Corrasion When a river picks up material and then rubs it against its bed and banks. Erosion

occurs by the process of abrasion. Most effective during times of flood. Main method of

both vertical and horizontal erosion.

Deltas River sediment deposited as a river enters lake, lagoon or ocean.

Discharge Volume of water flowing in a river at a particular point, during a particular period of

time.

Dissolved load Held in solution and can come from erosion, pollution, mineral springs and chemical

weathering.

Drainage basin Area of land that is drained by a river.

Drainage density Found by dividing total length of all streams in a basin (L) by its area (A).

Estuaries Drowned lower part of a river, as it enters the sea.

Evapotranspiration Water lost from vegetation via both evaporation and transpiration.

Groundwater Water held in the ground.

Hydraulic action Force of water that hits river banks, and then pushes water into cracks. Air becomes

compressed, pressure increased and the riverbank may, in time collapse.

Interception This is when plants prevent some rainfall from directly reaching the ground, for

example, water on leaves.

Infiltration Where water slowly soaks into the soil from the ground.

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Lag time Length of time between peak rainfall and peak discharge.

Overland flow Water flowing overland, often as a result of land being saturated.

Percolation Water in the soil does not remain there but moves down slowly into the lower layers of

soil and rock.

Potential

evapotranspiration

The amount of water that could be lost by evapotranspiration.

Regime Changes in the flow of a river throughout that occur with different seasons.

Saltation Pebbles, sand and gravel are lifted up by the current and bounced along the bed.

Solution/corrosion A continual process, which is as a result of the chemical composition of the water.

Storm hydrograph Graphs that show how a drainage basin responds to a period of rainfall.

Suspended sediment

load

Carried with the body of the current.

Suspension Very small particles of clay and silt are carried in suspension.

Tectonic change Where land is uplifted after plate movement or volcanic activity.

Traction Larger boulders rolling or sliding along the riverbed. Only experienced in times of great

flood.

Transpiration Loss of water from plants.

Throughflow Where water moves downwards through layers of soil.

Watershed Dividing line between drainage basins (usually higher ground).

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Population

Population statistics

Below are a few statistics you should learn:

1. The population of the world is growing by 2.7 people per second.

2. 95% of this growth is in the less developed world.

3. Today approximately one in three people are under fifteen. This has huge implications for future population

growth.

Population distribution

Population distribution - The way in which a population is spread over an area. This usually requires a

description.

Population density - The number of people per specified area, for example, population per kilometre squared.

This will be a figure, for example, 78 people/km2.

It is very common for the examiners to question you on your knowledge of population distribution at a global or

national scale.

Global distribution

On a global scale you will have to describe the global distribution of the population but will most likely be given a

map to help. Try practising using a population map from your atlas.

Perhaps more significantly you will have to be able to explain why the population is distributed the way it is. For

example, why are there large populations at X and a low population at Y?

A checklist of factors is given below. Make sure for each that you can explain the factor and an example

to go with it:

Physical factors - Relief, Water, Climate, Vegetation, Soil, Disease.

Human factors - Political, Economic, Resources.

Remember: Any population distribution is likely to result from a combination of factors.

National Distribution

You will also need to be able to describe the distribution of population on a national scale. Make sure that you

can draw a sketch map of population distribution, annotate and describe it with reference to places. You will also

have to explain reasons for distribution.

Population change

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Birth rate - This is the number of births per thousand people per year.

Death rate - The number of deaths per thousand people per year.

Natural change - This is difference between birth rate and death rate. It tells you by how much the population

will be growing per thousand of population per year.

The Demographic Transition Model - Shows how a development will affect birth rate and death rate and,

therefore, population.

Stage 1 of development BR (birth rates) and DR (death rates) are high so there is a low population.

Stage 2, DR has fallen but BR remains high. Natural increase is high.

Stage 3, BR also falls. Natural increase is high but falling.

Stage 4, DR and BR level out and population stabilises.

Stage 5, BR drops below DR so population is falling.

Migration

Migration could be described as a movement. It can involve a permanent or temporary movement and can be

voluntary or as in the case of refugees forced. You need to know five things:

1. Why do people choose to migrate?

2. What are the effects on the area they migrate to?

3. What are the effects on the area they leave?

4. What are the consequences for the migrant?

5. Case studies.

What are the consequences of migration?

You need to be able to talk about the consequences of migration on the areas the migrant leave, the area they

arrive in and on the migrants themselves.

Try and list Economic, Socio-cultural and political consequences.

Two case studies:

Transmigration in Indonesia.

Rural to urban in India.

Population characteristics

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Population pyramids - A way of displaying the age/sex structure of a population. We can analyse it to predict

the future and plan accordingly.

Dependency ratios - A ratio that compares the percentage of population available for work (15 - 64) and those

economically inactive.

Population structures - this is the age/ sex balance that exists.

Optimum, over and under population

Optimum population - The population is such that it can maximise the benefits from the resources available. It

is only when we have optimum population that the quality of life is maximised.

Over population - The resources cannot sustain the current population. As long as there is over population the

quality of life will decline through unemployment, pollution, degradation of the environment.

Under population - The population cannot fully utilise the resources available. Quality of life can only slowly be

improved. An increase in population would lead to an increase in quality of life.

Population policies

A population policy is a deliberate attempt by a Government to influence the population of a country. A

government could try to encourage or discourage population growth.

Case studies

1. China's one child policy - reducing the population.

2. France's attempt to boost population.

Population models

Malthus says population is controlled by food supply.

Boserup on the other hand said that food supply would increase to accommodate population growth.

You need to be able to explain each with arguments for and against.

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Introduction to Weather and Climate

Weather and climate

When referring to weather and climate it is important to distinguish the difference between the

two:

Weather

This relates to hourly, daily atmospheric conditions such as precipitation, hours of sunshine, cloud cover,

temperature and humidity. The most important fact is that it is short-term.

Climate

The climate of a place is based on the average weather conditions for a particular place taken over a minimum of

a 30-year period. It is a general picture and the weather received for a place can be vastly different from its

usual climate.

Recording data

Weather and climate is recorded in a variety of ways, but for an exam the most important points to know are:

1. How to interpret a climate graph.

2. How to interpret a synoptic weather chart.

Synoptic charts

synoptic chart shows certain meteological characteristics for specific weather stations, (usually pressure,

temperature, cloud cover, present weather, wind strength and direction).

In addition to this, satellite photographs are also used. Isobars are present on the map and are similar to contour

lines - the closer together they are, the stronger the wind is.

The diagrams below show the weather symbols for pressure and temperature, wind, weather and

cloud:

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Heating of the Atmosphere

There are four vertical layers within the atmosphere, each with its own particular characteristics. The outer limit

of the atmosphere is set at 1000km, but the vast majority of our weather and climate is found within the lower

12km.

Beginning at the earth's surface, the four layers of the atmosphere are listed below:

1. Troposphere

2. tratosphere

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3. Mesosphere

4. Thermosphere

Radiation

Short wave

Energy that comes from the sun and passes through the atmosphere to earth is in the form of short wave

radiation or insolation. It is responsible for the Earth's weather and climate and is converted via photosynthesis

to support all forms of life.

Long wave

Once insolation has reached the surface of the Earth, it is converted into heat energy. The ground begins to

warm and slowly heats the atmosphere above it, meaning that the atmosphere is warmed from ground level

upwards. The amount of heating of the atmosphere that occurs depends on the surface (for example, water, ice,

grass, sand) that is being heated.

Solar energy distribution

As energy passes through the atmosphere on its way to Earth, much of it is lost resulting in under 50 % actually

reaching the Earth's surface. Energy is lost via the processes of absorption, by ozone, dust, clouds and carbon

dioxide.

Scattering: This happens if gas molecules divert incoming radiation.

Reflection: Clouds reflect energy back into space (acts as a barrier).

Energy Transfers and Insolation

Energy transfers occur within the atmosphere in order to maintain a balance between the amount of energy

received at the poles and the equator.

Negative heat balance: Exists at the poles - a loss of energy to the atmosphere.

Positive heat balance: Exists within the tropics, a surplus of energy.

Heat transfers

Horizontal heat transfers

The transfer of heat from the equator to the poles occurs via winds - 80% (large scale to small scale) and ocean

currents (20%).

Vertical heat transfers

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Exist to stop the atmosphere from cooling and the Earth's surface from overheating. They occur via conduction,

convection, latent heat transfers and radiation.

Insolation

Long-term factors

These are factors which influence the amount of radiation reaching the Earth that remain relatively constant over

time.

Height of the Sun:

Lower latitudes (equatorial regions) have higher temperatures than higher latitudes (Poles) this is as a result

of the amount of heating that each area receives.

Height above sea level:

It is important to remember that the atmosphere is heated from ground level upwards via long-wave radiation.

Distance from land and sea:

Land and sea have vastly different specific heat capacities (the amount of energy needed to raise 1kg of a

substance by 1 degree).

Prevailing winds:

The temperature of a wind and the subsequent effect it has on an area is dependent on:

1. Where it originated.

2. The surfaces it has blown over.

Atmospheric Circulation and Motion

The tri-cellular model

This shows how energy is redistributed across the globe and ensures there is not a surplus at the equator and

deficit at the Poles. There are three major cells present: Hadley, Ferrel and Polar.

Atmospheric motion

There are two ways air can move in the atmosphere - vertically and horizontally (winds). Winds occur due to

differences in pressure, shown by isobars on a synoptic chart.

The Coriolis force

This relates to the apparent deflection of winds to the right in the northern hemisphere and the left in the

southern hemisphere due to the spinning of the Earth.

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Pressure gradient

The movement of air between areas of high and low pressure. Isobars show this phenomenon and the closer the

isobars, the stronger the winds. Winds act to balance out differences in pressure, humidity and temperature.

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Weather Conditions

Adiabatic lapse rate Used to explain what occurs as a parcel of air rises, decreases in pressure and

temperature, but increases in volume.

Advection cooling When warm, moist air is cooled as it crosses over a cooler sea or land surface.

Air mass Area of air with relatively uniform properties of temperature and humidity.

Anabatic winds Winds that blow up-valley, formed during warm afternoons.

Anticyclone Area of high pressure, descending/stable air giving rise to clear skies, and light winds.

Compression heating The contraction of air and associated temperature increase.

Convection rain Rain that forms as a result of intense ground heating.

Coriolis force Deflection of winds as a result of the rotation of the Earth.

Depressions Low-pressure weather systems formed along a polar front giving rise to strong winds,

cloud and rain.

Dry adiabatic lapse

rate

The rate a parcel of air cools at as it rises (or warms if falling) if condensation does not

occur.

Environmental lapse

rate

The average decrease in temperature with height (6.5 degrees per 1000m).

Fohn Air flowing over mountains causing a rapid increase in temperature.

Geostrophic wind Wind flowing parallel to isobars.

Jet streams Strong, fast moving winds found in the upper atmosphere.

Kanabatic winds Down valley winds.

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Lapse rates Rates at which air temperatures decrease with height. Variations exist between dry air

and saturated air.

Latent heat Heat that remains after energy has been used to convert water into water vapour.

Long-wave radiation Heat radiated from the Earth's surface that heats the lower troposphere.

Microclimate Area (often urban) that exhibits considerable differences in temperature, humidity,

clouds and precipitation, for example, from its surroundings.

Monsoons Seasonal reversals of wind direction that affect the Indian sub-continent.

Negative heat

balance

Exists at the poles - a loss of energy to the atmosphere.

Precipitation Rain, snow, hail, fog.

Orographic rain Rain formed as a result of relief that encourages warm, moist air to rise.

Positive heat balance Exists within the tropics, a surplus of energy.

Pressure gradient

force

Movement of air from areas of high pressure to areas of low pressure.

Radiation cooling When skies are clear at night, the ground loses heat very quickly. As a result, the air

directly above the ground also cools quickly. Fog and dew may form.

Rossby waves 'Wavering channels of air' formed by westerly winds, and relief barriers.

Saturated Adiabatic

Lapse Rate

The rate at which air cools if it has risen sufficiently to reach dew point temperature and

condensation occurs.

Short wave radiation Energy given off from the Sun.

Source region When air remains in one area for a period of time and it assumes the characteristics of

the surface over which it has been present.

Tri-cellular model Model that helps explain the transfer of energy within the atmosphere, and resultant

pressure belts.

Weather Relates to hourly, daily atmospheric conditions such as precipitation, hours of sunshine,

cloud cover, temperature and humidity.

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Coastal Processes

Backshore This area is not usually encroached upon by waves - unless storm conditions arise.

Foreshore and near

shore

The foreshore is located closest to the backshore and it is here, due to the breaking

of waves that sediment transport may take place.

Offshore There is limited direct sediment movement here as tidal currents are more important

than wave action.

Constructive waves These are depositional waves as they lead to sediment build up, and are most

common where a large fetch exists.

Destructive waves These act as agents of erosion, because backwash is greater than swash.

Wave fetch The distance of open water over which a wave has passed.

Wave crest Highest point of a wave.

Wave trough Lowest point of a wave.

Wave height Distance between trough and crest.

Wave length Distance between one crest/trough and the next.

Swash Water movement up a beach.

Backwash Water movement down a beach.

Abrasion/corrasion Occurs when material, such as sand, shingle, pebbles and boulders is hurled against

cliffs as waves hit them, wearing the cliff away.

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Hydraulic pressure When water is thrown against rock, a parcel of air can become trapped/compressed

in a joint or crack. The increase in pressure leads to a weakening/cracking of the

rock.

Corrosion/solution Seawater contains carbonic acid, which is capable of dissolving limestone. The

evaporation of salts in seawater produces crystals and their formation can lead to the

disintegration of rocks.

Sub-aerial

Coastal erosional processes that are not linked to the action of the sea. Erosion

occurs via rain, weathering by wind and frost. Its impact is often seen in soil creep,

slumping and landslides.

Human activity Much building and recreation occurs at the coast, and this increases pressure on cliff

"tops, making them more liable to erosion and subsidence.

Hard rock cliffs Examples include granite and basalt cliffs. They exhibit a slow rate of erosion and

tend to be stable.

Soft rock cliffs Examples include cliffs comprised of glacial till and clay. These cliffs often erode

rapidly.

Headlands and bays Hard rock, which resists erosion followed by soft rock that has been eroded to form a

bay.

Wave cut platforms These are gently sloping features, often found extending from the base of a cliff.

Caves, arches, stacks,

blowholes

Secondary features occurring during cliff formation. Originate due to lines of

weakness (joints or faults) being attacked and made larger by marine erosion.

Arch When two caves formed on either side of a headland join together.

Stacks Collapsed arches.

Stumps Stacks that have been eroded and lost height.

Clastic sediment Comes from weathering of rock and varies from very small clay particles to

sand/pebbles/boulders.

Biogenic sediment Skeletons and sediments of marine organisms.

Non-cohesive

sediment

Larger particles (for example, sand) moved grain by grain.

Cohesive sediment Very small clay and mud particles that bond together.

Longshore drift Process whereby material is moved along a stretch of coastline. Material is

transported in a zig-zag fashion.

Beaches Commonest form of coastal deposition - occurs as a result of sediment being

deposited, that may have come from rivers, and cliff erosion.

Spits Narrow, long stretches of sand/shingle that extends out to sea, or partway across a

river estuary.

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Sandy spits Form as a result of dominant constructive swell waves.

Shingle spits Form as a result of dominant destructive waves.

Tombolos Where a spit or bar connects the mainland to an island.

Barrier beaches and

islands

A number of sandy beaches that are totally separate to the main land, but run

parallel to it.

Cuspate forelands Triangular beaches formed by longshore drift operating on a coastline from two

different directions.

Sand dunes Not strictly a feature resulting directly from marine action, but the blowing of sand

from a beach inland.

Embryo dune The first part of the dune to develop.

Yellow dune Colour is due to a lack of humus, but with distance inland they become increasingly

grey due to greater amounts of humus.

Fixed grey dunes Limited growth due to distance from beach.

Dune slacks Depressions between dune ridges, which will be damp in summer and water-filled in

winter.

Blow outs Large ‘holes’ that appear in the dunes. Often evidence of over use by humans.

Mud flat A level area of fine silt along a shore as in a sheltered estuary. Alternatively covered

and uncovered by the tide, or covered by shallow water.

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Deltas, Estuaries and Changes to Coastal Areas

Deltas 3-dimensional features found where rivers that contain much sediment flow into the sea;

velocity is reduced and deposition of material occurs.

Estuaries Where fresh water (rivers) and salt water (sea) interact.

Accurate

estuary

Rounded, convex edges.

Cuspate

estuary

Material evenly spread from the river.

Birds foot

estuary

Spread over a wide area with many 'distributaries' extending out to sea.

Bottom set bed Have finest material, carried furthest in suspension and sinks to sea bed.

Foreset bed More readily deposited coarser material. Builds out to sea.

"top"set bed Deposits from river with the most coarse material.

Negative

change

A fall in sea level in relation to the land.

Positive

change

Sea level rises in relation to the land (or land sinking in relation to the sea).

Isostatic

change

Local changes in sea level, due to ice weight depressing earth’s crust lying beneath it.

Eustatic

change

Large scale/worldwide changes.

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Rias Drowned river valleys.

Fjords Flooded U-shaped valleys.

Fjards Glaciated lowland areas that have since been flooded.

Raised beaches Landforms that occur due to isolated uplift of the land in comparison to the sea, as the

weight of ice is slowly removed.

Hard

engineering

Structures that try to limit the impact on waves and their energy on a stretch of coastline.

Soft

engineering

More environmentally friendly - tries to work with natural processes to reduce, rather than

prevent erosion.

Managed

retreat

Nature is allowed to take its course. Sometimes seen as the ‘do nothing’ approach.

39

Agriculture

Types of agriculture

Classification

Term Definition

Intensive High input or yields for given area of land

Extensive Low inputs or yields for given area of land

Commercial Crops are cultivated and animals reared to be sold.

Subsistence Cultivating crops or rearing animals for consumption by the

farmer and his family.

Arable The cultivating of crops

Pastoral The rearing of animals

Mixed A combination of arable and pastoral

Agricultural systems

Subsistence farming

The aim of subsistence farming is to cultivate crops or rear animals for consumption by the farmer and his

family.

It is typical of agriculture in less economically developed countries.

Agribusiness

Agribusiness uses modern technologies to increase crop yields. Farmers produce cash crops for food or as a

raw material in manufacturing.

Farms are generally very large with high capital investment. This means that farms can benefit from economies

of scale.

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Collectives

Collectives refer to the situation where a farm is run by several people or whole communities who share in the

management, work and profits. The farms are usually government owned but the collective is given a permanent

lease.

These are a feature of agriculture in communist states such as China and North Korea.

Factors that affect the global distribution of agriculture

You will need to be able to discuss factors that affect the global distribution of agricultural systems. The

reasons are outlined below:

Physical

Climate

Climatic factors include...

Temperature - extremes prevent agricultural use.

Rainfall - reliability and distribution throughout the year are more significant that annual amount

Wind - can physically destroy a crop

Soil - certain soils favour certain plants

Slope - steep slopes encourage run-off and soil erosion rather than infiltration. They will only be used if

absolutely necessary

Human

Human factors include...

Land tenure - owner occupiers have the greatest incentives to increase yields

Market - farmers will grow crops that are profitable

Transport - see Von Thunen

Capital - will determine the level of technology a farmer can utilise

Technology - new technology can increase yields and affect the landscape

Government - policies will influence what systems a farmer uses or crops he grows

Von Thunen - provides us with an explanation of land-use. He uses locational rent to explain how land use will

change as you move away from an urban area. As you move away so intensity will decrease as a consequence of

inhibitive transport costs.

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Changes in Farming

One significant change in recent years has been the movement to organic farming.

We can define organic farming, as:

"Farming that does not use industrially produced chemicals as pesticide, herbicide, fertiliser. Nor does it use

drugs to increase the size/ yield of its livestock."

Organic farming has increased for two reasons:

1. It has been led by farmers with smallholdings who feel a deep commitment to the environment.

2. It is also consumer led as people are concerned about the chemical content and safety of many foods. The BSE

crisis has furthered the demand for organically grown food.

Impact of agriculture on the physical environment

Loss of natural habitat

Farming can lead to the loss of natural habitats.

The total amount of hedgerow removed or damaged is 6 x the circumference of the globe.

Reasons for loss of hedgerow?

Increased mechanisation in agriculture encourages farmers to increase the size of their fields. This they do by

removing hedgerows.

The following table outlines the arguments for and against hedgerows:

For hedgerow preservation Against hedgerow

preservation

They are a unique and balanced

ecosystem. They may harbour pests but

they also harbour the predator of that

pest

They can provide homes for pests

and weeds which damage crops

They contain a vast array of wildlife

including many endangered species and

they increase bio-diversity

They are a hindrance to the large

machinery that makes farming

efficient and reduces food prices to

the consumer

Evidence to suggest that they act as a They need to be maintained which

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natural barrier to the spread of disease.

They also act as wind breaks that protect

crops and reduce soil erosion

is costly

They are a part of our rural heritage They were planted by farmers in

the first place so are not traditional

Ps. 39 out of 42 hedgerow birds are beneficial to farmers.

Farmers to increase the available land and reduce the potential disease from stagnant water have drained ponds.

This removes another habitat for birds, fish, insects and plants.

The soil itself is an ecosystem and inappropriate farming techniques can lead to soil erosion. Overgrazing, over

cultivation and deforestation all damage the soil making it more prone to the effect of erosion.

In the developing world the pressure growing populations and foreign debt repayments has seen the removal of

natural vegetation cover to make way for cash cropping.

Use of chemicals

As farmers attempt to increase yields so they can increase their use of fertiliser, pesticides or slurry. Each of

these can have potentially damaging effects on the environment.

Eutrophication

Fertiliser and slurry are used to increase the nitrogen content of the soil so encouraging healthy plant growth. If

too much is used then it can be leached into underground water supplies and rivers. This is called eutrophication.

It then encourages algal and plant growth in the river or lake. These multiply rapidly then die off as oxygen is

used up. Bacteria then multiply as the plants decompose. These bacteria use up any remaining oxygen and

produce toxic bi-products. The lack of oxygen and increased toxicity kill fish life. This can encourage even more

harmful bacteria.

Pesticides

Another problem. In the developing world there are countless examples of pesticide poisoning. In the UK the

"Mammal Society" claim there are 24 species in danger of extinction as a consequence of pesticide use.

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