Geography revision

what is urbanisation

Urbanisation is the growth in the proportion or percentage of the world's population who live in cities

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why does urbanisation happen

Urbanisation happens because of a natural increase in the population and from migrations into cities

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how and why urbanisation rates change

rates of urbanisation vary across the world, richer, developed countries have a slower rate of urbanisation compared to poorer countries. Rates aren't spread evenly for example three countries (China,India and Nigeria) take up 37 percent of the rate

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why do cities grow

There are two ways a city grows (natural increase - when the birth rate exceeds the death rate)(Rural-Urban migration - when people move from the countryside to the city)

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why do people move from the countryside to the city?

there are push and pull factor on the next cards. but it is usually the young and economically active who make the move.

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push factors

push factors: 1. lack of employment opportunities 2. poor harvest leading to famine 3. drought and other climate hazards, such as flooding 4. subsistence farming, which doesn't bring any extra money to the family 5. very few services like doctors

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pull factors

pull factor: 1. better paid jobs 2. a higher standard of living 3. access to better education and health care 4. family and friends have already made the move to the city

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mega cities

mega cities are cities with a population of over 10 million

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challenges of squatter settlements

favelas have grown up and around rio de Janeiro. people have migrated from the north-eat of Brazil and the Amazon regions as they are looking for a better way of life but favelas are illegal settlements people have built homes on illegal land

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space for buildings

Greenfield sites are areas of land that haven't been built on and so it is a lot quicker and easier to build but this leads to urban sprawl (extending out from urban to rural. brown field sites are land that has been built on and you must re-develop

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changes in rivers and their valleys

A drainage basin is an area of land drained by a river and its tributaries. A river is divided into three section upper, middle, lower course and each of these has a distinct shape of the valley or river

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lower course

1. steep gradient 2. shallow depth 3. narrow, steep-sided channel 4. quite fast velocity 5. steep v-shape valley 6. waterfalls and interlocking spurs

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middle course

1. gentle gradient 2. deeper 3. flatter channel 4. faster velocity 5. u-shape valley 6. meanders

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Upper course

1.very gentle gradient 2.very deep 3.flat channel 4.very fast velocity 5.very flat valley 6. ox-bow lake and meanders

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fluvial process

erosion: the wearing away of materials by water - transportation: the movement of materials by water - deposition: dropping of materials by water

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hydraulic action

this is the force of the water hitting the river bank and river bed

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abrasion

the load that is carried by the river scrapes along the bank and bed and wears them away

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Attrition

the stones carried by the river hit each other and break up into smaller pieces

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solution

material is dissolved when the water travels over rocks, making the water acidic

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traction

large particles roll along the river bed

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suspension

smaller sediment floats in the water

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saltation

smaller particles bounce along the river bed

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solution

the dissolved material is carried in solution

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deposition

1. large rocks get deposited upper course 2 smaller particle held in suspension are deposited when a river slows 3. most deposition happens at the mouth

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what is a flood plains

a floodplain is a wide, flat area of land either side of the river

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how are floodplains formed

when a meander migrates from side to side causing the valley sides to erode and become wider, flat valley floor. 2. during a period of floods. silt is deposited on to the flood plain and builds up layer of fertile land.

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what is a levee and how is it formed

a levee is a raised river bed created by sediment from the river during a flood. materials are deposited and build up over time

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flood risk management

flooding occurs when there is an increase in the volume of water because of this it overflows on to the land sorrounding the river

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2x Physical factors (flood risk)

1. precipitation: a sudden heavy downpour can lead to flash foods or long periods of rain 2. saturated soil: waterlogged growned will not allow the water to soak in

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other 2x Physical factors (flood risk)

3. Geology: impermable rock that doesn't allow water to soak in which allows the water to run of the surface quicker to the river 4. steep slopes: water will run off a steep slope in a mountainous area quicker

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Human factors (flood risk)

1. Urbanisation: creates impermable sufaces like roads alsio drains and sewers speed the movement of water 2. Deforestation : is the removal of trees which means means less interpection which means water gets to the channel quicker

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Another Human factor (flood risk)

3. Agriculture: water travels quicker along ploughed and fields that are left unplanted

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Hydrographs

Hydrographs show the amount or volume of wtaer in a river after a storm. there are two types of hydrograph short lag and high peak or long lag and low peak

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where does long lag and low peak occur

they usually occur around 1. a large drainge basin 2. permable rock 3. forest 4. gentle relief 5. dry soil 6. light rainfall

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where does short lag and high peak occor

they usually occur around 1. small drainage basin 2. impermable rock 3. urbanisation 4. steep relief 5. saturated soil 6. heavy rainfall

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hard engineering

Hard engineering is the use of human-made structures to prevent or control flooding. these can be very expensive to install, but are often used to protect areas of high value, such as housing estates. Hard engineering schemes have a number of costs

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soft engineering

soft engineering is when natural river processes are managed to reduce flood risk.

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Afforestation

Afforestation is the planning of trees to increase interceptions and absorption of rainwater.

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Wetland and flood storage

Wetlands are areas of land that are allowed to deliberately flood and become flood storage areas.

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Floodplain zoning

floodplain zoning is where areas of land on the floodplain are divided up to allow certain types of land use. land nearer the river is used for low-cost uses, such as parkland. high-cost uses, such as housing and the further away the safer it is.

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river restoration

river restoration returns a river to its natural state and allows its natural features to slowdown water down water flow, such as meanders and wetlands

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Dams and reservoirs (benefits)

1. regulate flow of water 2. store water 3. allow for slow release of rainfall 4. multi-functional (hydro electric power).

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Dams and reservoirs (costs)

1. very expensive 2. flood large areas of land permanently 3. people moved from their homes

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channel straightening (benefits)

1. speed up the flow of water 2. protects the vulnerable area next to the channel

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channel straightening (cost)

1. increases flood risk downstream 2. silt can build up in concrete channels 3. concrete channels are unattractive and unnatural

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Embankments (benefits)

1. raised river banks allow the river to hold more water during a flood 2. can be sustainable if dredged material is used 3. protect towns and cities from flooding

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Embankments (cost)

1. high concrete walls can look unattractive

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Flood relief channel (benefits)

1. new river channel bypasses the urban area 2. redirect the river away from from a town during a periods of heavy rain

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Flood relief channel (cost)

1. expensive

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scale of ecosystem (small scale)

small-scale local ecosystem such as ponds or sand dunes. small scale ecosystems are influenced by local factors such as rock type, soil characteristics and amount of water

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scale of ecosystem (large scale)

large-scale global economic such as tropical rainforests, hot desert or tundra these are sometimes called biomes which are affected by global factors

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interactions within ecosystems

there are two parts 1 abiotic means the non-living parts of an ecosystem, such as soil and water 2. biotic means the living parts of an ecosystem, such as plants and animals these interact with the nutrient cycle and the water cycle

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food chain

a food chains where living things are placed in a line of what eats what

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food web

a food web is where many food chains link together within an ecosystem with certain living thing being the food for several creatures or one creature eating lots of things

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producers part 1

primary producers are sometimes known as autotrophs - these are plants that automatically convert sunlight, water and minerals through the process of photosynthesis into energy starches so that they can grow

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producers part 2

plants are the basis for all the other levels of creatures in an ecosystem, as they are the food for consumers like leaves

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consumers

consumers are either herbivores/primary consumers, carnivores, or omnivores.

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decomposers

when producers and consumers die, they accumulate on or in the ground where decomposers break them down into basic minerals

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nutrient cycle 1

mineral nutrient accumulate in soil, dissolve in rainwater and are absorbed by plants through their roots. some important minerals are carbon, nitrogen and phosphorus

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nutrient cycle 2

nutrients help plants grow and the minerals are then passed on to the consumer and the cycle is complete when the leaves become litter and decompose into the soil and so they become biomass

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balance

a natural ecosystem develops a balance between all of its parts over a long period of time. in this way, ecosystems remain stable unless they is a big change.

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change caused by human activity

when humans remove natural vegetation or alter ground to create farmland. they create greenhouse gases and climate change

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change caused by physical conditions:

small-scale UK ecosystem may face extreme weather conditions such as drought or storms

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tropical rainforest

tropical rainforests are located mostly between the tropic lines either side of the equator. the largest concentration is in South Africa

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why are tropical storms in these areas

these areas are very hot and for most of the year although some exist where there isa dry season. average temperature are between 27oc and 30oc . its is very hot because the the suns energy is concentrated on a small surface area

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vegetation (tropical storm)

the vegetation is based on layers of trees, which thrive due to the ideal combination of sunlight, heat and water because they have more than 2000

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hot deserts

hot deserts are found either side of the tropic of cancer and the tropic of Capricorn where it is dry and hot over 30oc with less than 250mm rainfall a year

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het deserts part 2

hot deserts are found where air sinks on a large where air sinks on a large scale as part of the global atmospheric circulation, such as the Sahara in Africa. it is so hot because the moisture has been left behind

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vegetation ( hot deserts)

there are not many plant because of the lack of moisture and poor soil - only a few that have adapted, often by storing water - and animals usually only come out at night

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tundra

tundra ecosystem are found in zones in and around the polar regions. there is only a small amount of tundra in the southern hemisphere because there is a limited land at the latitude

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tundra temp

temperatures are below 0oc for most of the year and peak at about 10oc and the precipitation is below 250mm because of evaporation

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tundra vegetation

there aren't many plants because it is so cold. plants grow low to the ground to avoid the bitterly cold

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tropical rainforest structure (emergent layer)

there are the tallest trees over 50m like kapok these are known as the emergent layer

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tropical rainforest structure (canopies)

below the emergent layer is a least two levels of trees which form canopies from there dense green leaves. the main canopies are about 35m tall (most food is found here)

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tropical rainforest structure (shrub layer)

below the canopies is the shrub layer where enough sunlight gets through the canopy layers. there is very little vegetation at the ground level as it is quite dark, which means that there is less food for animals at ground level

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the growing season

the growing season for plants is about 12 months, as it is always hot and wet. with such a wealth of food it is not surprising to find that the tropical rainforest is the most biodiverse ecosystem on the planet, 50 percent of the species live there

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how it effects the tropical rainforest

the hot, wet conditions also speed up nutrient cycling. the largest store of nutrients is in the large trees. the litter from these decomposes quicker in the top soil layer

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soil nutrient

the soil lacks nutrients because the nutrient are recycled quickly back into the plants

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interdependence (nutrient flow)

the nutrient flow in a tropical rainforest is fast because it is so hot and wet and therefore, chemical reactions are faster. leaves and branches that fall on to the ground decompose quickly and so the roots of the trees absorb them quickly

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interdependence (soil)

the soils are not very fertile. they lack nutrients because of leaching. most nutrients in the tropical rainforest ecosystem are stored in the vegetation

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interdependence (moisture)

trees transpire moisture through their leaves, which then evaporate into the air this is called evapotranspiration which creates large amounts of humidity

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adaptation by plants

1. growing tall to reach the sunlight 2. they have larger leaves that pivot on their stalks to capture sunlight 3. having waxy leaves so that heavy rainfall runs off 4. shallow roots to obtain nutrients 5. buttress roots that give stability

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adaptation by animals

1. monkeys and other mammals can swing and climb 2. gliding snakes fatten themselves into a ribbon to glide between trees 3. flogs lay there tadpoles in pools of water to protect them 4. insects developed camo

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Biodiversity issues

1. extinction of species endangers others 2. loss of genetic material from which we find medicine 3. unbalanced ecosystem

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impacts of deforestation

1. the soil maybe exposed by deforestation, enabling the rain to wash it a way so nothing will grow

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rates of deforestation (old)

humans have always cut down the tropical rainforest. tribes made their homes from the timber clearing small areas and farmer took them down to farm. however it was sustainble

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rates of deforestation (new)

modern humans with technology, such as machinery and because of this they cut down the trees to make the space and as the population grows they expand further

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rates of deforestation (over time)

deforestation rates have varied over time depending on economic influence such as demand for certain materials or crops. however at the current rate the tropics will be gone in 100 years

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sustainable management

ways of decreasing deforestation

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value of tropical rain forest (people)

1. for some the rainforest was a place that provides shelter and food 2. for people with economic motives there is timber, crops and other food which is of value 3. and for some the rain forest they balance the oxygen level

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value of tropical rain forest (natural environment)

it is known that the tropic rainforest ecosystem has an influence on local climate and scientists think that it will affect global warming 2. it is the oldest dime and has a greatest biodiversity by far 3. it acts as a store of carbon

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sustainable strategies (selective logging and replacing)

selective logging involves choosing carefully where to extract timber and so if we extracted a wide range instead on one which would lead it to extinction 2. and even if you do log to stop deforestation and desertion we should replant

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sustainable strategies (conservation)

conservation means looking after the forest so that he can conserve national parks and forest

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sustainable strategies (internatonal agreement)

people would make agreements to lower other countries dept do they wouldn't have to sell of chop down trees.

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Hot desert (characteristics of hot desert)(weather)

Hot deserts have an extreme climate compared with many others on earth. the hot desert is really dry and has less than 250mm of water which means not much life can grow and the average daytime heat is 50oc but it is a lot cooler at night the reason

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Hot desert (characteristics of hot desert)(biodiversity)

the ecosystem is not very biodiverse with few plants and animals due to lack of water and poor soil

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Hot desert (characteristics of hot desert)(physical lands)

deserts are often thought of as a sea of sand with dunes, but many desert areas are rock or consist of salt flats as well as having sand dunes.

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Hot desert (characteristics of hot desert)(desertification)

Deserts may increase in size of surrounding areas become drier or are mismanaged by people - a process called desertifiaction

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Hot desert (interdependence)

indigenous people have adapted to the climate conditions and natural patterns. crops are difficult to grow and animals have had to go place to place for water

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hot deserts (adaptation of plant)

1.long, deep roots or wide shallow roots to reach the water 2. ability to store water 3. in sync with the growing cycle for when it rains 4. thick outer layer or waxy skin 5. cactus have turned leaves into spines to block sun and stop insects

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hot deserts (adaptation of animals)

1. camel store fat in the hump 2. many animals come out at night because its cooler 3. rely on food for water 4. some beetles collect water when it condenses on their bodies

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hot deserts (biodiversity issues)

deserts have low biodiversity. although the plants and animal have adapted there still vulnerable and because the emission to greenhouse gases have caused climate change which causes long periods with out rain

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hot deserts (opportunities and challenges)

even though the hot and dry desert climate presents human survival challenges but there are opportunities such as solar farming

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desertification

desertification means turning semi-arid areas into desert

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hot deserts (desertification)(causes)

1. natural climate change may be responsible 2. the average temperature has increased by about 1oc since the industrial revolution 3. in the last 40 year climate change and changed the rainfall pattern have changed 4. rain is heavy and doesn't soak

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hot deserts (desertification)(population growth)

the population of the world has increased dramatically and this includes semi - arid areas and because they are more people need water and food so it is used to expand farming 2. because of lack or resources people are forced to move making it worse

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removal of fuel wood

with poorer people in the desert there is a higher demand for fuel for cooking and so they chop down trees to extract the fuel and when the roots of the tree die the soil goes dry

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overgrazing

As more people are forced to live in semi arid areas and the cattle is there money but they eat the grass it then dries it out and is consumed by the desert

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Over-cultivation and soil erosion

over-cultivation is where people use land too much beyond the level or repair

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strategies to reduce risk (water and soil management)

1. irrigation methods can make the water last longer using the appropriate technology like a well 2.building terraces on slopes to create flat land which reduces run off water 3. soil can be conserved by not over using/ protecting using wind breaker

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strategies to reduce risk (tree planting)

there are some types of trees or bush that have adapted more to arid environment. these can be used to keep soil together.

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use of appropriate technology

1. using small metal cookers that require a smaller quantity of wood. or solar cooker 2. building dams or bund out of rocks

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