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2012 Topical Notes
[CORE PHYSICAL GEOGRAPHY] Lim Ting Jie VS Class of 2011
TOPIC 1: PLATE TECTONICS AND RESULTING LANDFORMS What is the Plate Tectonics Theory? Tectonic plates are pieces of the Earth that make up the surface of the Earth and are in constant
motion. It describes the Earth as restless and suggests that the Earth’s crust is made up of 7 major
crustal plates. Why do the plates move? 1. There are convection currents in the mantle which drag the plates above them. 2. Magma in the mantle is intensely heated, expands and rises. The rising magma spreads out below the plates, cools and sinks. 3. The continuous heating and cooling of the magma set up convection currents in the mantle. What are the differences between continental plates and oceanic plates?
CONTINENTAL PLATES 1. carry the continents 2. mainly made up of continental crust with oceanic crust lying beneath it 3. consists mainly of granitic rocks (lighter in colour, less dense) 4. rich in sial (compounds of silicon and aluminum) 5. discontinuous, forming the continents 6. Examples: Eurasian African North American
South American Indo-Australian Antarctic
OCEANIC PLATES 1. lie beneath the oceans 2. mainly made up of oceanic crust 3. consists mainly of basaltic rocks (darker in colour, denser) 4. rich in sima (compounds of silicon an magnesium) 5. continuous, forming the ocean floors and bases of continents 6. Examples: Pacific Caribbean Nazca Cocos Philippine Scotia
Oceanic-oceanic divergent plate movement (South American and African plate Mid-Atlantic ridge) 9+1
C F B S S P M D V O
Convectional currents in mantle result in tensional divergent plate movement
Cause the African plate to be pulled apart from the South American plate Fractures and cracks appear Basaltic magma flows out from the mantle Spreads outwards along the fractures Magma solidifies and forms new crust or new sea floor at the constructive boundaries Causes old crust to be pushed away from plate boundary by sea-floor spreading More basaltic magma piles up and solidifies forms a chain of mountains known as midoceanic ridges on either side of the spreading zone Youngest mountains are the closest to the spreading zone while the oldest are the furthest away from it (distancing) Mid-Atlantic ridge, part of it rises above the sea to form a chain of volcanic islands (i.e. Iceland) Rift valleys, submarine rift volcanoes and earthquakes also form (others)
Continental-continental divergent plate movement (African and Arabian plate East African Rift Valley) Convectional currents in mantle result in tensional divergent plate movement Cause the African plate to be pulled apart in opposite directions along the eastern and western rifts from the Arabian plate C Plates are pushed upward as well Both plates are continental F Hence cracks to appear known as normal faults with further tensional forces Faulting Further application of pressure More tension is generated B African plate starts breaking into several blocks like the Somalia block, Nubian block and Tanzania block M Further application of pressure generates more tension Central block of rocks start moving up along the fault lines to form block mountains V Some parts slip down along the fault lines to form rift valleys The rift valleys get filled with water over time L Form lakes like Lake Victoria and seas like the Red Sea Upwelling of magma along the fault line which escapes onto the Earth’s surface R Builds up into rift volcanoes like Mount Kilimanjaro and Mount Kenya
6+1
*How is the appearance of the East African Rift Valley described? 1. Apperance: Stepped appearance presence of multiple fault lines cause blocks to be displaced in relations to each other 2. Mountains: Blocked mountains formed as raised blocks on either side on the rift valley 3. Escarpments: where faults have developed and the centre block subsided 4. Lakes: where water accumulates within the valley or depression 5. Volcanoes: where magma escapes through cracks or faults and solidifies Continental-continental convergent plate movement (Indo-Australian and Eurasian plate Himalayas) T
Large area of sedimentary layers in the Tethys Sea once separated Asia and India Convectional currents in mantle result in convergent plate movement 7+2 Cause the two land masses surrounding the Tethys Sea, Eurasian plate and IndoC Australian plate, to converge L N C B S A G
Oceanic lithosphere subducts beneath the Eurasian plate Both plates made of relatively light and buoyant rocks with equal thicknesses and have similar densities There is no subduction between the two plates Rock strata along the boundary are compressed Continental sedimentary rock layers between the plates are forced to buckle and fold Sediments are scraped off from the edges of the Indo-Australian plate Build up and accumulate to form the continental fold mountains Himalayas Indian landmass still pushing into Eurasian plate Himalayan mountains still growing skyward about 5 cm per year
What are the differences between faulting and folding?
FAULTING [C-C=D]
FOLDING [C-C=C]
1. rocks are displaced relative to each other to cause breaks or fractures in rocks 2. caused by stresses and strains in rocks of two plates as they move in response to convection currents 3. frequent in areas with brittle rocks (igneous and metamorphic rocks) 4. stores up stress and suddenly releases it, causing earthquakes
1. rock strata along the boundary are compressed to cause the strata to buckle and fold 2. caused by the bending of the Earth’s crust under the pressure of compression 3. frequent in areas with sedimentary rocks 4. gradually releases stress
Oceanic-continental convergent plate movement (South American and Nazca plate Andes) 8+1
C D S D T F S S V
Convectional currents in mantle result in tensional divergent plate movement
Cause the Pacific plate to be brought towards the Philippine plate Plates are pushed upward as well The oceanic Nazca plate, being thinner and denser Subducts under the thicker, less dense continental South American plate Dipping of oceanic plate into the mantle Forms a long, deep and narrow trench Peru-Chile of about 8000 m deep Continental South American plate rides over Nazca plate Part of the ocean floor is scraped of Edges and sediments near the edges and on the ocean floor are folded and crumpled Thick layers of squeezed sediments rise to form the fold mountains Andes Edges of Nazca plate melt as it gets pushed into the mantle Forms silica rich magma at destructive boundaries Magma formed by melted oceanic crust erupt Rises to Earth’s surface through fractures Forms subduction volcanoes Nevado del Ruiz and the Cotopasi volcano
Oceanic-oceanic convergent plate movement (Pacific and Philippine plate Mariana islands) 8+1
C D S D T F S U V
Convectional currents in mantle result in tensional divergent plate movement
Cause the Pacific plate to be brought close to the Philippine plate Plates are pushed upward as well The Pacific plate, being furthest away from sea-floor spreading and hence denser Both plates are continental Pacific plate subducts under the less dense Philippine Both plates Dipping of Pacific plate into the mantle Forms a long, deep and narrow trench Mariana Trench of about 11 thousand metres deep Both plates are about the same density as both are very dense No blucking occurs No fold mountains are present Edges of Pacific plate melt as it subducts under the Philippine plate Forms silica rich magma at destructive boundaries Magma formed by melted oceanic crust erupt Rises to Earth’s surface through fractures Forms undersea submarine volcanoes Volcanoes build up and appear above the sea to form volcanic islands
Transform plate movement (Pacific and North American plate San Andreas Fault) 1. Both plates slide past each other lateral movement occurs 2. There is little volcanic activity and crustal material is neither created or destroyed along the conservative plate boundary 3. Plates grind against each other as they move in opposite directions tear faults form cause earthquakes due to the great amount of stress built up How are the landforms formed by faulting and folding different?
PROCESS
RESULTANT
Types of folds
Symmetrical fold Asymmetrical fold Overfold Recumbent fold Overthurst fold
CONSEQUENCES Both limbs are of equal steepness One limb is steeper than the other One fold is pushed over the other limb Limbs are nearly parallel to each other One limb is pushed forward and overrides the other
EFFECT Compression from opposite sides is equal Compression is greater from one side than the other side Increasing compression Increasing compression Fracture occurs along the fault plane
Normal fault
Types of faults Reverse fault
Tear fault
Two blocks of rocks are pulled apart, forming a steep cliff or scarp Tensional forces cause rocks to break and fractures to form Land in between the fault sinks
Two blocks of rocks are compressed, forming an overhanging escarpment Compressional forces cause rocks to break and fractures to form
Two blocks of crust left standing above the surrounding land as block mountains Graben forms between the fault
Two blocks are uplifted to form block mountains
Graben forms between the fault
Occurs when adjacent blocks slide past each other horizontally along the fracture
Block mountains
When a block mountain is horizontal, it is called a horst. However, erosion and weathering may reduce the horst to a range of rounded hills.
Graben
When the graben is widened, an elongated deep valley with two high blocks at the sides known as the rift valley is formed. Lakes and volcanoes may form on the floor of a rift valley. Faults provide a passage for magma to rise to the surface to form rift volcanoes
Types of landforms
What is the distribution of earthquakes and volcanoes around the world due to plate movements? 1. Earthquakes and volcanoes are found along plate boundaries where they are areas of instability. 2. Constant plate movement where plates converge, diverge or slide past one another give rise to earthquakes and volcanoes.
3. Other landforms that forms that the zones Mid-oceanic ridge
O-O=D C-C=D O-C=C O-O=C C-C=C
Rift valley
Oceanic trench
Fold mountains
Volcanoes
Earthquakes
Few/none
Transform
4. Circum-Pacific Belt / Pacific Ring of Fire a. Zones of colliding or sliding plates which stretch from New Zealand, South Western Pacific, Indonesia, Philippines, Japan, past the Aleutian Islands, Alaska in North America, down the Cascade Range and Andes Mountains on the west coast of South America. 5. Mediterranean-Alpine Belt / Alpine-Himalayas-North India system a. Zones of colliding plates which stretch from the Himalayas to the Alps and the Mediterranean region. 6. Belts of minor (earthquake) activities a. Mid-Atlantic Belt that coincides with the belt of volcanic islands in Atlantic Ocean and is in the zone of diverging plates beneath an ocean. b. East African Rift Valley which is in a zone of diverging plates beneath a continent 7. Areas of minor (volcanic) activities a. Hotspots found away from plate boundaries in the interior of the plates like the Hawaiian islands and Easter island give rise to volcanoes Describe the main types of volcanoes and account for the differences in their shapes
COMPOSITE VOLCANO 1. Lighter pyroclasts erupts first, then followed by lava composed of alternate layers of pyroclasts (ash and cinder) and acid lava 2. Viscous (moves slowly and cools quickly) forming steep slopes at the top gentler slopes at the base 3. Solidifies in central pipe, building up pressure, resulting in a violent eruption lighter pyroclasts fall around the vent the top to be steeper than the base 4. More lava and pyroclasts are added to the volcano constant elevation of volcano
ACID VOLCANO
SHIELD VOLCANO
1. Composed of layers of acid lava
1. Composed of layers of basic lava
2. Viscous (moves slowly and cools quickly) forming steep slopes 3. Solidifies in central pipe, building up pressure, resulting in a violent eruption steep slopes of acid lava only
2. Fluid (moves quickly than acid lava and spreads out far before cooling) gentle slopes 3. Spreads out quickly before cooling gentle slopes broad base
4. More lava added to the volcano constant elevation of volcano
4. Spreads out quickly, solidifies usually near base constant widening of volcano’s base area
Earthquakes Danger and direct effects of earthquake
Landslides
Fires
Infrastructure collapse
a) b) c)
Tsunamis
d)
e) f)
Diseases spreading
Lives lost
Example 1999 Taiwan Earthquake caused many vehicles travelling along were swept down mountain slopes. Entire villages were buried under the massive landslides.
Soil on hill slopes loosen Large amounts of rocks and soil from a hill slope slide down. People and infrastructure like roads and water pipes may be buried under the soil. Caused by damaged wires, overturned stoves and broken gas pipes when the ground shakes. Fires can cause deaths and the collapse of infrastructure, leaving more people injured and homeless. Furthermore, water, electricity and gas supplies and emergency services would be disrupted, delaying the help given to the affected regions. Infrastructure may not be designed to withstand earthquakes as they are built on weak foundations. Some earthquakes may not cause immediate collapse on infrastructure, but may weaken the foundations of buildings and transport networks. Repair works has to be carried out; otherwise the affected infrastructure may collapse within months. Constant movement of 2 (named) tectonic plates due to convectional currents under the mantle This results in the build-up of pressure and stored energy due to the unsmooth movement of the plates Stored energy is released when the rocks snap and fissure causes the sea level to dip temporarily Sudden movements in the sea bed and underwater vibrations along the plate boundary result in a series of giant waves. The waves travel at speeds of up to 800km per hour across the ocean. Increased friction between the waves and shoreline reduces the speed of the waves, slowing down the waves to a huge wall of up to 6m before crashing onto land. Impacts and long-term effects of earthquakes Homeless people put in temporary shelters like schools and tents. Temporary shelters usually overcrowded and lack of proper sanitation. Poisonous materials from broken sewage pipes can cause diseases like typhoid and cholera. Results from fires, collapse of buildings or tsunamis causing severe injuries and death Aftershocks delay rescue efforts and endanger rescuer’s lives
1995 Kobe Earthquake in Japan caused many wooden houses to catch fire and leaving the inhabitants homeless.
1999 Turkey Earthquake caused 4000 buildings to collapse as they were not built to withstand earthquakes.
2004 December undersea earthquake occurred in the Indian Ocean near Sumatra, triggering tsunamis. These waves travelled thousands of kilometers before crashing onto the shores of Indonesia, Thailand, Sri Lanka and India.
Example
Haiti earthquake 2010 resulted in more people dying and falling ill instead of the earthquake itself due to the spread of diseases
2005 Kashmir Earthquake destroyed many houses, took away many supplies and left many roads buried under rubble
Economic impacts
Trauma
Impacts and long-term effects of earthquakes Inconvenience may be caused to the business area with the destruction of roads, industrial buildings, water pipes and electrical supplies Tsunamis by undersea earthquakes can destroy habitats of marine life, decreasing the amounts of fish and prawn farmers catch Hard to live with loss of families and friends Ongoing triggers bring back the trauma like taking transport or deadly silence
Example
2004 Indian Ocean Tsunami caused Phuket to suffer a drastic drop in the number of visitors
1985 Mexico City Earthquake caused many civilians to be seen suffering from uncontrollable crying and fits of anger even after a few years since the earthquake.
Success of preparing for an earthquake 1. Education and Drills Complacency Drills are conducted regularly to educate and familiarise The success depends solely on the people on what to do. people. In Japan, students have to crouch under the nearest If they are complacent and do not table when the earthquake signal goes off. see the importance of earthquake Posters and signs are put up to show evacuation routes so education, they will be less that people do not panic and can move to safer regions prepared when an earthquake immediately. strikes. 2. Planning of location of infrastructure Difficult control of land use Local authorities must determine the nature and extent However, in developing countries, of earthquake risks in earthquake-prone areas. it is difficult to control land use They can control land use so that houses or tall buildings as population growth is fast. are not built in earthquake prone areas. Also, people migrate from rural Authorities were able to determine the nature of the areas to cities and build their earthquake risks in Washington by estimating the level of homes illegally on earthquake expected ground shaking and identifying the sites prone prone areas without approval to ground failures and tsunamis. from authorities. 3. Designing new infrastructure Expensive to construct Steel bars are used in the cross-bracing method to Transamerica Pyramid in San strengthen new infrastructure to be better equipped to Franciso costed S$75 million to withstand earthquakes build Shock absorbers are used in foundations to help absorb Poorer places in the world may tremors of the earthquake not be able to afford such Transamerica Pyramid in San Francisco was able to technology withstand the Loma Prieta Earthquake of 7.1 on the Richter scale 4. Earthquake monitoring and warning system
Factors influencing earthquake extent
The strength of the force the earthquake releases. [1] Magnitude
[2] Distance from epicentre
[3] Population density
[4] Level of preparedness
3 on the Richter scale usually cannot be felt. 8 causes total destruction, destroying even concrete structures.
Places near the epicentre (i.e. point on the Earth’s surface that is directly above the focus of an earthquake) generally receive the strongest shock waves due to shorter wavelengths. Hence they are most likely to receive the greatest damage.
Earthquake
More deaths
Less deaths
1993 Maharashtra Earthquake India
Village of Killari (nearer to epicentre)
Village of Gulbarga (further away)
If the population density of an earthquake-prone area is high, the chances of many people being killed or injured will be high. During the earthquake of Anchorage, Alaska in 1964 of magnitude 9.2, the death toll was only 115 as it had a small and sparse population then
When drills are not conducted regularly in earthquake prone areas and posters not put up to keep people on guard, these people will not be familiar of what to do in the event of an earthquake. Also, if it has been a long time since a major earthquake occurred, they tend to be less prepared. Citizens of Tokyo are aware that it is an earthquake prone area but are less prepared compared to other parts of Tokyo as the last major earthquake was in 1923.
People who live in areas with soft soil tend to be affected more greatly on areas of hard solid rock.
[5] Type of soil
Soft soil tends to amplify the effects of an earthquake, infrastructure more likely to cause damage These places are hence at a risk of greater damage than other towns and cities around it
Earthquake
More damage
Less damage
1985 Mexico City Earthquake
Mexico City (further away from epicentre, but lies on soft soil)
Acapulco (nearer to epicentre, but lies on hard soil)
TOPIC 2: WEATHER AND CLIMATE 1. Weather and Climate and their elements Weather Climate Temperature Maritime effect Continental effect Altitude Relative humidity Precipitation Air pressure Deflection
The conditions in the atmosphere at a specific place over a relatively short period of time The average atmospheric conditions of a specific place over a considerable period of time (>30 years) The degree of hotness and coldness of a place The effect large ocean bodies have on the climate of coastal areas (that causes coastal areas to have a smaller temperature range annually) The effect that continental surface have on the climate of inland areas (that causes inland areas to have a larger temperature range annually) The height of a point above sea level. Where A = x m, θ = (32.5 - 0.0065 x) °C The proportion of water vapour present in the air to the maximum amount that the air can hold at a particular temperature Water falling from the atmosphere to the Earth’s surface The downward force exerted by the weight of air per unit area on the Earth’s surface The change in the direction of winds by the Coriolis effect
2. Monsoon winds due to the Coriolis effect
Southwest Monsoon June to September
Northeast Monsoon October to January
Monsoons in greater detail Northern Hemisphere experiences summer with warm air while Southern Hemisphere experiences winter with cold air Warm air is less dense than cold air Low pressure develops over Indian sub-continent while high pressure develops over the Australian continent. Hence the Southwest Monsoon blows from the Australian continent across the Indian Ocean and the Bay of Bengal, picking up large amounts moisture. Heavy rains are brought to Southwestern India and Bangladesh, experiencing hot and wet climate Northern Hemisphere experiences winter with cold air while Southern Hemisphere experiences summer with warm air Warm air is less dense than cold air High pressure develops over Indian sub-continent while low pressure develops over the Australian continent. Hence the Northeast Monsoon blows across the Asian continent and Indian Ocean, picking up large amounts moisture. Heavy rains are brought to Australia, experiencing hot and wet climate No rain is brought to countries like Bangladesh due to the dry winds from Asia.
3. Types of climate in the world
Locations
Latitudes
Tropical equatorial climate
Tropical monsoon climate
Singapore (experiences generally lower
Myanmar, India, Sri Lanka, Thailand,
temperatures and higher rainfall from
Taiwan, Vietnam, Pakistan (the
October to March), Indonesia, Malaysia,
above are TOC areas), Africa (E),
Congo Basin of Africa, South America
Madagascar, Brazil (N and
(N and E), Brazil (NE)
E) , Australia (N)
SIMCSA Between 10˚ N and S
MISTT, VPAMB 10˚ to 25˚ N and S
Cool temperate climate Canada, USA, New Zealand, Japan (N), Europe (NW), Korea, China (SE area may be affected
by monsoons) (only the above are located in the N Hemisphere), Chile (S), Argentina (S) CUNJEK, CCA 35˚ to 70˚ N and S
4. Factors affecting temperature at a location #
1
Factor
Latitude
2
Altitude
3
Distance from sea
Description At low latitude, Sun’s rays reaching areas near the Equator are concentrated on the Earth’s surface almost perpendicularly, resulting in high temperatures Angle of incidence of the Sun’s rays strike lower latitudes at an acute angle, heating it up more intensely than higher latitude areas Places located further away from the Equator receive less direct sunlight At lower ground surfaces, air is dense Contains more water vapour and dust particles BY ENVIRONMENTAL Heat energy escapes from the surface slowly LAPSE At lower ground surfaces, air is more rarified and RATE Contains little water vapour and dust particles Heat energy rapidly escapes from the surface During winter, air above land is cooler than the air above sea. The Land absorbs and loses coastal areas are hence warmer than inland areas. (Coastal area heat faster than the sea have cooler summers and warmer winters) as the sun has to penetrate deeper into the During summer, land is warmer and the cool air from sea brings oceans to heat it up than the temperature of the coast down. (Inland areas have warmer the shallower land summers and cooler winters)
Examples / Locations Tropical equatorial climate Tropical monsoon climate Cool temperate climate
Areas of high altitude
Areas at the coast and areas inland
#
4
5
Factor Aspect (direction of a slope relative to the Sun)
Length of day
6
Winds
7
Ocean currents
8
Seasonal monsoon winds
9
Cloud cover
10
Varied Sun positions
11
Equatorial climate
Description
Examples / Locations
In N hemispheres, S-facing slopes receive more direct sunlight and are warmer than N-facing slopes
Cool temperate climate in N hemispheres
In S hemispheres, N-facing slopes receive more direct sunlight and are hotter than S-facing slopes
Cool temperate climate in S hemispheres
Longer days More time for the Earth’s surface to absorb Sun’s energy Warmer days
-
Shorter days Less time for the Earth’s surface to absorb Sun’s energy Cooler days Offshore winds (Land breeze) Onshore winds (Sea breeze, wind from sea over land near coasts) Winds which has blown over a warm current will have its temperature raised
Areas near coasts
-
Winds which has blown over cold current lowers its temperature. Dry weather results from May to September Moist onshore winds pick up moisture from the Indian Ocean during the Southwest Monsoon Cool weather results from May to September Dry weather results from December to March Moist winds blow offshore due to the Northeast Monsoon from the interior of India Cool weather results from December to March More cloud cover in wet season reduces incoming solar radiation and outgoing terrestrial radiation In summer, from about May to July, the Earth’s axis is tilted such that the Sun is overhead the Tropic of Cancer. More daylight hours than in winter Higher temperatures compared to winter Temperature is high all year round
Australia (monsoon) Southeastern China, Taiwan, Hong Kong, (monsoon) India and Bangladesh (equatorial) Australia (monsoon) Areas experiencing monsoon winds Tropical monsoon climate at the Tropic of Cancer areas
Tropical equatorial climate
5. General temperatures in the world climates
Temperature
Tropical equatorial climate
Tropical monsoon climate
Cool temperate climate
High and uniform throughout the year
High and uniform throughout the year
High in summer, Low in winter
High mean 27°C
High mean 26°C
High mean -5.5°C to 2.3°C
Low range 25.7°C < T < 27.5°C
Low range but higher than equatorial climate 24.4°C < T < 30.2°C
High range varying from 15°C to 30°C -19.1°C < T < 19.7°C
Statistics
Reasons
Mean 1) Latitude 9) Would be higher if not for the thick cloud cover Range 9) Cloud cover 11) Temperature is high throughout the year
Mean 1) Latitude 8) Monsoon winds that create 9) More cloud cover 10) Varied Sun positions Range 9) Cloud cover in wet season
Mean 1) Latitude Range 3) Continentality
6. Factors affecting rainfall at a location #
Factor
A
Convectional rain
B
Relief rain and “rain shadow effect”
C
Global atmospheric processes
Description Earth’s hot surface heats up the air above it, causing air to rise quickly. Condensation occurs and clouds are formed. Heavy rain accompanied by thunder and lightning falls. Warm air continues to rise and condensation continues to occur, and only eases when moisture is lost. Wind picks up large amounts of water vapour from water surface of water body. Relative humidity of the air increases. Air is forced to rise above the nearby highland. Air becomes saturated when it reaches a particular altitude and temperature falls. Relief rain falls on the windward side when the clouds can no longer hold the water droplets. Air is warmed when the winds descend and moisture is lost. Hence air is dry on the leeward side. El Nino, abnormal warming of the surface at Southeastern Pacific Ocean for several weeks, every La Nina follows after El Nino, occurring three to seven years every three to five years. Ocean off the coast of South America heats up Heavy rains are experienced in Trade winds push warm surface waters eastwards Indonesia and Australia Peru and South America has more heavy rains
Locations Tropical equatorial and monsoon climate (areas of high humidity) Coastal areas between a large water body and a nearby highland Peru in South America (equatorial) Indonesia (equatorial) and Australia (monsoon)
7. General rainfall in the world climates
Rainfall
Reasons
Tropical equatorial climate
Tropical monsoon climate
Cool temperate climate
High 2343.7 mm Even 158 < R < 282.8 A) Relative humidity is high, above 80%. C) Western South America and Indonesia receive heavy rainfall during the El Nino and La Nina periods respectively 8) Monsoon winds and Convectional winds 11) High temperatures cause water to evaporate rapidly into the air
High 2146.1 mm Distinct 0.5 < R < 751.4 B) Places to the sea and on windward slope with receive more seasonal rainfall C) Australia may receive heavy rainfall during the La Nina period 8) Monsoon winds blowing in opposite directions from September to October
Moderately low 525.3 mm Even 17.4 < R < 80.1 A) Low temp prevents air from holding much moisture hence low humidity A) In summer, higher temperatures result in higher evapotranspiration rates and in rainfall slightly heavier B) High when moisture is brought onshore by winds towards highlands causing relief rain
8. Climate change
Enhanced greenhouse effect
Rapid increase in use of fossil fuels
Large-scale clearing of forests
Global warming The greenhouse effect occurs when greenhouse gases absorb heat from the Sun’s rays and trap it in the atmosphere. With an increase in world population, more greenhouse gases are released and trapped in the atmosphere. This enhanced greenhouse effect causes a rise in the Earth’s average global temperature known as global warming. Rapid increase in the use of fossil fuels in vehicles and factories has led to high levels of greenhouse gases released into the atmosphere. The usage of chemicals like chlorofluorocarbons found in aerosol cans, refrigerators and air-conditioners, has also contributed to the enhanced greenhouse effect by depleting the ozone layer. Large-scale deforestation and forest fires have reduced the amount of vegetation cover on the Earth’s surface. Trees and other plants take in carbon dioxide and release oxygen through the natural process of photosynthesis. When more trees and other plants are cut down or are destroyed by forest fires, less carbon dioxide is absorbed from the atmosphere.
Example Many countries such as Papua New Guinea and Afghanistan have been significantly increasing the world population growth rate, which stands at 1.17% currently. Many large nuclear power plants that emit tons of gases to the atmosphere are built in Korea and China to accommodate the large amount of people in their countries. Forests are cleared for timber and mining, and to create land for other activities such as agriculture and urban development Forest fires in Australia and Indonesia
Increased cultivation and livestock rearing
Increase of domestic waste
Global warming Increase in the levels of greenhouse gases due to agricultural activities like wet rice cultivation and cattle ranching. The cultivation of rice in padi fields and the use of inorganic fertilisers release methane and nitrous oxides into the atmosphere. The rearing of cattle and other livestock releases methane into the atmosphere as the result of the animals’ digestive processes. More and more domestic and organic waste is being buried in landfills. The decaying of rubbish produces methane, which adds to global warming as a greenhouse gas.
Example Australia is known for high levels of cattle ranching and large areas in Southeast Asia grow padi as food for consumption. Poland produces 3 million tons of rubbish per year and relies on many landfills to clear the rubbish.
9. Floods
Natural causes
Excessive rainfall
Global atmospheric processes
Storm surges
Description Tropical monsoon climates have moist monsoon winds blow over land Heavy prolonged rains Excess water unable to seep into ground Rivers overflow banks E.g. El Nino, abnormal warming of the surface at Southeastern Pacific Ocean Ocean off the coast of South America heats up Trade winds push warm surface waters eastwards Occurs when strong winds raise waves in the ocean to high levels Flood coastal areas when the giant waves crash
Human causes
Example Description In China, where rivers Clearing of forests increase In China, the Yangtze are high, forests in deforestation and decrease River are usually flooded mountainous regions are vegetation to intercept as rains wash large cleared to create land rainwater amounts of sediments into for housing and wood for Bare slopes promote surface the river, causing rivers to fuel, increasing frequency runoff that increases become shallower. of floods. surface runoff Laboratories in Louisiana Increase in human activities Peru and South America, has estimated a 1½ feet has enhanced global warming as heavy rains are brought increase in sea level Ice cover in polar regions away from them past the there and parts of are reduced Pacific Ocean to South California to ½ foot Low-lying coastal regions may America increase in sea level in face the possibility of the next 50 years flooding 80% of Bangladesh sits on In London, areas around Concrete pavements and floodplains surrounding River Thames experience tarred roads has replaced the river system like regular flooding due to vegetation and soil Ganges and 35% less than urbanisation, increasing Interception of rain is lower 6m, prone to storm surges surface runoff Groundwater decreases
Forest clearing
Enhanced greenhouse effect
Urban development
Natural causes Melting snow
Movements of the Earth’s surface
Lives lost Damage to infrastructure Diseases spreading
Environmental damage
Impact of floods Floodplains provide fertile alluvium, making them very attractive for cultivation of crops, and hence densely populated More lives are hence lost when a flood occurs at these lowlands unexpectedly Homes are ruined and weakened by floodwaters, damaging property and infrastructure Disrupts power supply and phone lines, cutting off communication. When people evacuate to makeshift shelters, they are usually overcrowded, lacking sanitation and drinking water. Malaria and cholera are common diseases. Destruction of trees, other plant life and natural habitats of animals
Fertile soil for agriculture
Description In cool temperate climates, the melting snow releases large amounts of water into rivers Rivers overflow their banks when they are unable to hold excess water Soil may loosen along mountain slopes during an earthquake and cause landslides When deposited into a nearby river, it reduces the capacity of the river and water is made easier to overflow its banks.
Advantages of floods Regular flooding of rivers provides soil along river banks with fertile alluvium, making the soil suitable for farming Many people hence live on low-lying plains near rivers despite the risks.
Example St John River in Canada had a flood in 1986 Several homes submerged in flood waters Families had to be evacuated from flooded areas Landslide triggered by heavy rains along steep banks of the Yangtze river in China makes the surrounding areas more prone to floods
Examples
Heavy downpour led to rising floodwaters in the northerncentral Huai River Basin in China in 2003, claiming 298 lives and more people to evacuate to elsewhere
Hurricane Katrina in USA 2005 led to massive flooding of several states around the Gulf Coast Flood damage in New Orleans costed around US$44 billion
Dhaka, Bangladesh 2004, extensive flooding forced people to take cover in makeshift shelters Crowded and unsanitary Tsunami in Southern Java in 2006 flooded coastal regions to cause severe damage to coastal ecology like the Pangandaran Beach Examples
Nile Delta in Egypt is where crops are commonly cultivated because of the fertile alluvium deposited and flooded fields
Building control
Post flood management measures Watershed management
When a severe flood occurs, the authorities may decide to evacuate flood victims to shelter.
The watershed is managed directly to deal with floods Planting of trees and grass on slopes reducing surface runoff and soil erosion to decrease chances of flooding Provides people with financial resources to rebuild their property if a flood strikes. People pay different amounts for the insurance depending on the history of floods in the location.
Dykes
Dams
Education and monitoring
Adaptations to cope with floods Walls of sand, stone and concrete built along river banks Increase the capacity of the river Chances of flooding is reduced Walls of dams have gates to hold back or release water from the man made reservoir behind it Controls the amount of water that flows downstream Increases amount of water upstream Scientists are able to monitor weather patterns and issue warnings when a flood is about to occur Authorities use them to put up warning signs at flood prone areas.
Flood insurance
Adaptations to cope with floods Local government draw up maps to show areas prone to flooding Developers ensure that flood would not affect the buildings they construct
Examples Singapore Ministry of Environment of Water Resources requires ground levels to be raised in low-lying areas Has successfully reduced flood prone areas from 1970 to 2006 by 90%. Victims were evacuated by boats and helicopters to temporary shelters like the unused New Orleans Airport in Hurricane Katrina in USA in 2005.
Royal Forest Department in Thailand developed a programme Detailed plans to conserve vegetation cover, surface runoff and amount of sediments washed into the rivers and replanting of trees
The government in United Kingdom has a national flood insurance programme to help reduce financial burden of the people who have lost their homes due to a flood. Examples
Dykes has been built along the Yellow River in China for centuries. Three Gorges Dam in China was constructed in 2006 to overcome floods by water control Evacuation plans to the safest and fastest route are created in the USA for the people to seek flood shelters on higher grounds
Disadvantages Continual build-up of sediments on river bed makes channel shallower and water levels to raise higher over the years. Sediments regularly dug up from the bed. The reservoir slows down the speed of water in the river More sediments will accumulate in the reservoir to raise the reservoir bed Unanticipated floods The success depends solely on the people. If they are complacent and do not see the importance of flood education, they will be less prepared when a flood strikes unexpectedly in their region.
10. Droughts Natural causes Human causes Description Examples Description Bangladesh and India Cleared forests Deforestation in when monsoon winds Ground exposed to direct heating Delayed or This is found in arid areas Amazon rainforest are delayed due to the Soil dries up quickly insufficient like the tropical monsoon where miles of exposed differences in Lower transpiration rates rainfall regions near the Equator banks are dried up or pressure in Australia Less water vapour in atmosphere eroded by wind and its continent. Fewer clouds E.g. El Nino, abnormal Kothariya in India has Rapid population growth Indonesia and warming of the surface at experienced droughts More water needed for homes, Australia, as heavy Global Southeastern Pacific Ocean for a decade where industry and agriculture rains are brought away atmospheric Ocean off the coast of population of 4000 has Rivers and ground-water will be from them past the processes South America heats up used up all water holes more heavily depended on Pacific Ocean to South Trade winds push warm and wells and have to dig Livestock will be badly affected in America surface waters eastwards deep into the ground these areas High temperatures and global Sahel in Africa is warming cause rapid evaporation located near the Equator Land, lakes and rivers dry and water bodies are Droughts occur when rain does not limited fill water bodies
Resources of water and food shortage Environmental damage Forest fires and haze
Impact of droughts People and animals die from dehydration and famine due to failing crops and droughts prevents the necessary conditions for growth Affecting many developing countries Desertification due to prolonged droughts in arid regions With little or no rain, dry soil is unable to support vegetation growth Soil is blown away to leave a barren land No rain for a long time Vegetation becomes dry Easy to catch fire Winds blow across forests Blankets cities and haze to produce effects of SO2 and NO2 (Chem)
Reduced forest cover
Water over usage
Enhanced greenhouse effect
Examples 2006 Ethiopia drought left 737 thousand people struggling and had to rely on water provided by the government water tankers Sahara desert expansion in 1968 due to prolonged droughts, resulting in the loss of trees and greenery in the environment, promoting global warming Australia has frequent droughts that has destroyed forests spanning many hectares, spreading smoke to other parts of the world by monsoon winds
Adaptations to cope with floods
Examples In Mongolia (water-scarce) laws are implemented to limit number of trees being cut down like the use of firewood only
Watershed and agricultural management
Management measures like the planting of thousands of seedlings and planting of specially adapted plants can help to cope with floods
Proper irrigation techniques
Irrigation brings water to areas receiving little or no rainfall through manmade channels. Proper irrigation and save water for other uses in droughts.
Turkey farmers use spray irrigation where precision sprinkers drip small amounts of water onto crops to reduce water loss and save water for other uses.
Cloud seeding
Dispersal of silver iodide and dry ice into the sky airplanes to induce easier formation of water droplets and rain
It was used in Malaysia and Thailand in 2005 in hope to end the prolonged droughts in rain harvests. It eased the drought by 80%.
Post drought management measures
Countries affected require assistance from other countries or international aid organisations
US Agency for International Development (USAID) provided donations of money, food and water to Ethiopia during the 2006 drought
Israel farmers plant apple cacti as they require less water and can bear fruit for up to 92% of the time
Disadvantages However, some groups in the world like Kothariya in India do not have the unity or technology to implement the laws. They Lack of technology require the importing of food and the switch of staple diet, and the UN would have to supply these requirements. It is hard to find the perfect irrigation method to suit the development of the area. For example drip line irrigation Hard to suit area enables water to seep directly development through the roots effectively, but is expensive and farmers may not be able to afford it. However the cost is high and success is not always guaranteed as some areas like India may experience abnormal Guarantee of success atmospheric process and deter the functions of clouding seeding.
CHAPTER 3: WEATHER AND CLIMATE & NATURAL VEGETATION Biome profile (Rainforest, Monsoon and Coniferous) Tropical monsoon forest Temperature coniferous forest
Tropical equatorial rainforest Dense and abundant vegetation growth, very luxuriant 30 m - 50 m Made up of tallest trees
To reach out for sunlight
V
Fewer non-parastic plants
Prevents sunlight from reaching forest floor
Few non-parastic plants 5 m - 6 m Tree saplings and woody plants 0 m - 5 m Sparse Little sunlight reaches the vegeta- floor as emergent and canopy tion areas spread out like umbrellas
U. S S U. G
U.S
-
Evergeen and found close together
To withstand strong winds
Uniform height and conical shaped
Sways instead of toppling
Little undergrowth
0 m - 5 m Poorly leeched soils Little sunlight reaches floor Thin layer of leaf litter Needle-shaped leaves do not favour fast decomposition
0 m - 6 m Dense vegetation, more undergrowth, shed leaves
Sunlight able to reach the ground when trees
Tropical equatorial rainforest
Understorey
Lianas (thick woody vines, up to 90m), Epiphytes (grows on trees for support, rainwater and decaying leaves land on for supply of water and nutrients), Raflessia (parasitic, competes with host tree, causing the death of the tree) Shrubs, ferns and small young trees
Undergrowth
Small plants, ferns, fungi, saprophytes, decaying leaves
Canopy
C
6 m - 15 m
Smaller trees with narrow crowns
Dense and abundant in coniferous trees
V
20 m - 30 m
C
6 m - 15 m
Examples
V
E
15 m - 30 m Continuous and interlocking
Less dense than rainforest, more open, less luxuriant 25 m - 30 m
U.G
E
U.G
Tropical monsoon forest
Temperature coniferous forest
Teak, sandalwood and sal
-
Thick shrubs, bamboo (thickets), grasses and herbs
Mosses and lichens
Diversity of plant species
Useful species
Tropical equatorial rainforest
Tropical monsoon
Tropical mangrove
Temperate coniferous
Largest diversity of plant species in all biomes
Mostly hardwoods
Made up of halophytes (salt-tolerant plants)
Softwood found in the trees, which grow in pure stands
Keruing, Kapur, Chengal, Meranti Making furniture
Summary
Large variety of plants due to high year round temperatures and rainfall, 750
Reasons
For fuelwood
For making incense
Fewer species due to inconsistent rainfall, 200
species/ha
Extremely dense and abundant
Abundant but less dense than tropical rainforest during dry season
Mostly similar to tropical rainforest during wet season
High temperatures and rainfall
Crowns do not interlock to form a continuous canopy, denser undergrowth
More abundant leaves
Plants lose/shed their leaves
Density
Sandalwood
Sparse during dry season
species of trees and 1500 of plants/ha
Sal
AviSonSea Rhizo- Brucenn nerahibisphora geria ia tia cus ConsMeFiretruction Charcoal dicine wood materials
Nipah palm
Fir
Food
Paper
Plants have to be adapted to growing in salt water
Dense and luxuriant
High temperatures and rainfall
Canopy competes continuously for sunlight resulting in sparse undergrowth
Spruce
Pulp
Matches
Pine Furniture
Chem . products
Plants have to be adapted to low temperatures and precipitation,
1-3 species/area
Not dense
Low temperatures and precipitation
Avi.
Characteristics similar to equatorial climate
Bruguiera
Rhizophora
Absorb salt and store them in old leaves Sonneratia
Avicennia
To regulate the amount of salt in the tree as they grow in salt water
Evergreen
High constant rainfall through -out the year
No shedding of leaves Constant rainfall, loss of water need not be highly reduced
Large and broad
Waxy with drip tips
To maximise surface area for photosynthesis
To allow rainwater to drain off easily to prevent bacteria from growing on them (as high temperatures promote growth of bacteria)
RhizoColourful and sweet smelling, present all phora year round Colourful Waves/ Fruits bright red currents elongated, lantern carry Still air at canopy area do not allow shape - sharp tips buoyant Traits - Anchor pollination to be carried out by wind and Attract fruits to and Pros can only rely on insects for pollination new insects: for firmly in places to pollination muddy soil and animals for dispersal Flowers and fruits
Tropical monsoon Deciduous (shed leaves during dry season)
Bamboo plant have narrow leaves during dry season
To minimise loss of water through transpiration
To minimise of loss water through transpiration due to lack of water during dry season
Brugeria
They are leafless during this period
To reduce loss due to transpiration
The ground will be frozen and little water available
Male
Female
Produce pollen
Produce seeds (dispersed by wind or animals)
Protect the seeds from the cold Thick and coarse Protects trunk from heat and dryness during dry season
Withstand extreme heat from natural forest fires
Located around the middle of trunks Sunlight better able to reach the lower parts of the forest
Thick barks
Flexible branches
Conical shape (some)
Snow can slide off easily preventing breakage
Withstand strong winds by swaying
No need for protection against cold or dry conditions
Emergent and canopy layers branches spread out like umbrellas to get maximum sunlight
Store water during winter
Protect from long cold winters
Pros
Thin and smooth barks
Branches found only on the top one-third of the trunks
Needlelike
Bear cones
Usually only present during dry season
take root
Bark and branches
Temperate coniferous
So that photosynthesis can occur all the time
Reasons
Tropical equatorial rainforest
Mostly evergreen
Leaves
Secrete excess salt
Tropical mangrove
Roots
Pros
Tropical equatorial rainforest Shallow and Buttress spread roots widely present Roots do not need to reach deep into soil for water and nutrients
Tropical monsoon Deep roots
Tropical mangrove Aerial roots / Pnuematophores (exposed during low tide) Avicennia
To support the great weight of the trees
To tap water sources deep under the ground
Sonneratia
Peg-like, Pencil-like, able thick base to grow 30m high Exposed during low tide and able take in oxygen from the air during this period
Temperature coniferous
Prop / Stilt roots
Kneed roots
Rhizophora
Brugeria
To anchor trees firmly in muddy soil, protecting coastal areas from strong waves
To provide firm support on soft soil
Shallow and spreading roots
To absorb water easily from soil surface when snow melts, as during winter, snow falls instead of rain
Roots are specially adapted to oxygen-deprived soil Reasons
Leaf litter decomposes and humus form to supply nutrients to the topsoil
Rainfall is not regular throughout the year
The trees grow on soft and waterlogged soil that lacks oxygen
Precipitation is low throughout the year, resulting in little water in the ground
Biome profile (Mangrove)
Soil stability Density of leaves Distance from sea
Coastal zone Avicennia and Sonneratia Aerial roots / Pnuematophores
Shore
Zone Species of trees Types of roots Tolerance in salt water Sanility Inundation (water cover)
Middle zone Rhizophora Prop / stilt roots Increases
Increases
Inland zone Bruguiera Knee-like roots
Functions of forests
Rnfst Mnsn Mngr Cnfs
Habitat for flora and fauna
Habitat for people
Water treatment
Home to more than half the species in the world
About 60 million people live in tropical rainforests of SA, SEA & Africa
Mangrove forests process waste materials like dead animals and human waste carried by water
Tigers and rare Hunter animals gatherers Tropical Korubu tribe rainin Amazon forest hunts wild in Peninanimals sular Gathers Malayleaves for sia subsis-tence Grizzly Shifting bears cultivators Coni Grow crops ferous on forest forests land cleared of by burning North America
Roots of mangrove trees help trap waste materials and filter water before it flows into sea Soil contains bacteria that can break down biodegradable waste, converting into nutrients for themselves Some countries channel sewage portions to mangrove forests to treat waste
Green lungs of the Earth
Medical uses
Water catchment
Forests prevent global temperatures from rising
Some plants in forests have medicinal value, which some has yet to be fully explored
Enable water to be collected, stored and maintained
Protecting coasts
Preventing floods
Mangroves are able to protect coastal areas
Roots reduce chance of the river overflowing banks
Quality maintenance Leaves and branches Acts as a Soil During Sarawak intercept rain falling on barrier erosion photosyn Calophyllum has a ground surface from is slower thesis compound that strong Soil Less surface Forests take may be able to Less waves makes runoff More in carbon prevent fullsoil and the river groundwater dioxide, a blown AIDS parstorms bed Rivers and greenhouse Brazillian ticles In 2004 shallower reservoirs gas produced rainforest are Indian Ability Vegetation by humans Quinine from wash Tsunami , of the transpires to Release Cinchona in can ed it proriver to release water oxygen, be used to treat into tected contain vapour into replenishing malaria nearcoasts of the the oxygen supply Coniferous forests by Southern water is atmosphere, This helps Cough syrup rivers India inencouraging regulate from barks of and from creased cloud temperature Eastern white reser destrucwith formation and on Earth Pine trees -viors tion roots rain
Quantity maintenance
Functions of forests Research and education
Chemicals
Food
Recreation
Timber
New medicines and varieties of crops developed
Some useful chemicals are extracted from forests
Forests also provide people with food (e.g. Borneo:)
Provides ecotourism to many city-dwellers
Timber can be used to make furniture and paper and construct buildings
New medicine and crops Banana, coffee and cocoa are cultivated for food, new ones are constantly discovered Effect on ecosystems on life Scientists study interactions between forest, animals and plants like the effect of weather
Mangrove trees in East Africa Tannin from Rhizophora treat leather Tree sap Black dyes Pine and fir trees Resin Wood varnish and ointments
Sago from sago palm High in starch concentration Edible ferns Midin Forests provide the perfect location for animal hunting Wild deer for meat
Rafting, hiking and birdwatching is engaged so that the environment is not harmed Otherwise, tourists entering the forests have to follow rules and regulations Tamam Negara in Malaysia is promoted as ecotourism to gain income while protecting the forest
Rnfst Mnsn Mngr Cnfs
Tropical forests Chengal and meranti trees Rattan for furniture and baskets Coniferous forests Pine trees Mangrove forests Leaves of Nipah palm can be made into thatched roofs Monsoon forests Bamboo for buildings
Fuelwood and charcoal Wood and charcoal is used for cooking and heating for 2 billion people in the world Less developed countries like Asia and Africa gather wood from forests as fuel Rhizophora is being cut down to make charcoal in the Matang Forest Reserve in Peninsular Malaysia
Causes of deforestation Forest fires
( Forest fire control) Demand for agricultural landuse
Most of the forest fires are deliberately set up by people Plantation companies start forest fires to clear large areas of rainforest for growing oil palm Some of the fires are also due to dry weather Vegetation debris that are left on the forest floor like branches and twigs catch fire easily Causes increase in demand for land which result in population pressure in area near forests New settlers near forests permanently clear forests to grow crops in small holdings Small farms such as rice and cocoa are grown for own use, for sale and profit
Caused deforestation of more than 23750 km2 of Kalimantan between 1997 and 1998 Indonesian government population programme eases overcrowding in islands like Java and Sumatra
Causes of deforestation As population increases and settlements become crowded, more land is cleared for housing People start moving from rural settlements to urban settlements to live and work due to more opportunities for employment Rainforests are cleared
Growth of settlements
Improved transport networks
Roads and railway tracks are constructed to link settlements in Kalimantan Allow access to previously remote forested areas in Kalimantan Lengths of forest trees had to be cut down to clear the path Logging (timber being cut down and sold) Pace of logging is increased by timber companies to ensure that the processing facilities are fully utlitised Mining (extraction of gold, silver and copper underneath the forests) Vegetation has to be cleared to expose the ground underneath A large hole has to be created, exposing loose soil
Growth of industries
( Logging control)
Balkapapan in East Kalimantan is a business centre for many national companies dealing with mining and oil extraction and this reduced the are from 98.7 km2 to 35 km2 in one year Trans-Kalimantan Highway between Balikpapan and Banjarmasin is 230 kilometres long and cuts through rainforests. This has made it easier for people to destroy more forest areas.
1656 km2 of forest is removed West Kalimantan annually A mining company was awarded a contract to mine 1290 km of the rainforest since 1980. Large expanse has been cleared.
Problems caused by deforestation Loss in biomass /diversity (
Af/reforestation)
Changes in the nutrient cycle Vast changes in water
Stored energy of the organisms represents the total amount of food available on Earth Ability of the rainforests to support various plant and animal life is reduced as the food chain is adversely affected. Survival of herbivores and carnivores will be threatened due to the loss of plant food sources. Biodiversity of plants and animals in the Kalimantan forests are reduced Less leaf litter Lack of vegetation cover Roots are absent Less decomposed No protective cover for soil Absorption of rain reduced material Soil exposed to rain and erosion Soils are leached topsoil becomes Slower fertility rate Loss of soil nutrient infertile cannot support growth Droughts - Less transpiration Cloud formation is reduced Rainfall is lowered Floods - Roots are not present Soil is loose Eroded and goes into rivers Decrease river capacity Muddy waters - Increased amounts of soil Increased sediment level of rivers Unclean waters Acidity of rivers - Increased amounts of soil Increased sediment level of rivers Water becomes more acidic Inversely affects aquatic life in the rivers Less fish catch by fishermen
Extinction of species in the Kalimantan may result. The Proboscis monkey in the Kalimantan rainforest is being endangered. Little of original vegetation can be replaced back and cleared land is unsuitable for cultivation Droughts have been caused during 1997-98 Severe floods in 2001 in Samarinda and Balikpapaen
Problems caused by deforestation Air pollution
Dust and smoke released during clearance of trees by burning, causing air pollution If more severe, the particles were be suspended in air and be blown by strong winds Haze found in other areas like Southeast Asia from Central Kalimantan, many suffered from eye, nose and throat irritations
Tropical Rainforests Large and broad To maximise surface area for photosynthesis Waxy with drip tips To allow rainwater to drain off easily to prevent bacteria from growing on them Branches found only on the top onethird of the trunks Emergent and canopy layers branches spread to get maximum sunlight Colourful and sweet smelling fruits To use insects for pollination and animals for dispersal Roots shallow and spread widely, buttress roots present To support the great weight of the trees
Summary of the adaptations of forests Tropical Monsoon Forests Mangrove Forests Deep roots Leaves able To tap water sources deep under the secrete or store ground as rainfall is not regular throughout excess salt the year Regulate the amount Thick and coarse of salt in the tree Protects trunk from heat and dryness as they grow in salt during dry season and withstand extreme water heat from natural forest fires Flowers are Waxy with drip tips generally colourful To allow rainwater to drain off easily to To attract insects prevent bacteria from growing on them to pollinate flowers Deciduous (shed leaves during dry season) Specially adapted To minimise loss of water through roots transpiration Like aerial, prop and Bamboo plant have narrow leaves kneed roots to grow To minimise of loss water through on soft and transpiration due to lack of water during waterlogged soil dry season that lacks oxygen
Flights had to cancelled to the Southeast Asian region due to poor visibility in 1997
Coniferous Forests Needle-like To reduce loss due to transpiration Leaves able to store water The ground will be frozen and little water available during winter Flowers bear cones Protect the seeds from cold Thick barks Protect from long cold winters Flexible branches Snow can slide off easily preventing breakage Mostly conical shaped Withstand strong winds by swaying Shallow, spreading roots To absorb water easily from soil surface when snow melts, as during winter, snow falls instead of rain
Nutrient cycle dissolved in rainfall from atmosphere surface runoff leaching weathered from rocks
LITTER
decomposes
nutrient transfer to SOIL
tissue fallout
plant uptake
BIOMASS
Nutrient cycle characteristics in forests Equatorial rainforest
Largest store of mineral nutrients
Biomass Total mass of living organisms, mainly plant tissues
Tall, dense and rapid vegetation growth High annual temperature, Year long with high and even rainfall growing season
Limited despite continuous fall of leaves
Litter Total amount of organic matter (e.g. humus and leaf litter in soil) Soil Naturally occurring unconsolidated or loose covering Earth’s surface
Composed of several layers of plant species
Hence rapid decomposition of dead vegetation Hot and wet climate provides ideal environment for bacterial action
Rich in nutrients but easily leeched and washed by runoff
Temperate Coniferous forest Relatively low (unsorted) Needle-like leaves Littler undergrowth One layer of coniferous Limited variety of species trees only
Largest store of mineral nutrients
Contains few nutrients (unsorted)
Soil has to rely on replacement of nutrients from chemical and biological weathering of the bedrock
Lost through leeching and surface runoff
Litter content is rapidly reduced
Low fertility potential of podsol soil of tiaga
Tropical Rainforests 1. Habitat for flora and fauna 2. Habitat for people 3. Green lungs of the Earth 4. Medical uses 5. Water catchment 6. Preventing floods 7. Research and education 8. Food 9. Re-creation 10. Timber 11. Fuelwood & charcoal
Summary of the functions of forests Tropical Monsoon Forests Mangrove Forests 1. Research and education 2. Chemicals 3. Food 1. Water treatment 4. Recreation 2. Green lungs of the Earth 5.Timber 3. Water catchment 6.Fuelwood and charcoal 4. Protecting coasts 7. Habitat for flora and fauna 5. Preventing floods 8. Habitat for people 6. Research and education 9. Green lungs of the Earth 7. Timber 10. Water catchment 11. Preventing floods
Low temp restrict the rate of chemical weathering of parent rock, slow replacement rate Needle-like cuticles discourage decomposers and breakdown of leaf litter to humus
Coniferous Forests
1. Habitat for flora and fauna 2. Green lungs of Earth 3. Medical uses 4. Research and education 5. Chemicals 6. Recreation 7. Timber
Measures to reduce deforestation Forest fire control
Afforestation and reforestation
Logging control
Implement policies to make it illegal to clear forests by burning Conduct annual forest fire awareness campaigns Plant trees on area not originally covered with forests Plant trees in formerly forested area cleared by logging Careful management of forests with the use of law enforcement, education and research programmes Severe penalties such as fines and imprisonment are enforced for irresponsible timber companies for illegal logging
Indonesian government introduced measures to to monitor forest fires through forest fire campaigns in 1996 and National Fire management plan in 1999 Afforestation is carried out on agricultural lands located on fringes of villages and existing forests MOF set out to restore 900 000 hectares of forests annually in Kalimantan through the Forests and Land Restoration Initiative with local people involved in the replanting of trees
However, rates of the forests being replanted are slower than the forest being cleared as the incentives may not be attractive enough for the people to participate in the projects
Ministry of Forestry (MOF) has arranged for education and research programmes for timber companies Selective cutting is encouraged so that much of the forest is undisturbed
Conservation
Careful use of resources like forests to protect them from destruction
MOF sets aside nature reserves like the Betung Kerihum Nature Reserve (Heart of Borneo) WWF works closely with Kalimantan, Brunei and Malaysia to protect the reserve
However, some plantation companies continue to burn for profit as it is the cheapest way to clear land Some local people are also too used to their traditional farming methods inherited from the past
However, it is difficult to monitor logging and detect illegal logging activities due to the lack of manpower and remoteness of the forest Some places has allowed illegal logging to go undetected Also, trees selectively removed may also affect un-removed trees However, it is difficult to monitor logging and detect illegal logging activities due to the lack of manpower and remoteness of the forest Treasure Island at Risk reported the presence of illegal logging in 2005
TOPIC 4: RIVERS 1. River terminology Drainage basin Watershed Channelisation Wetted perimeter
the land area drained by the main river and its tributaries the imaginary line acting as a boundary separating one drainage basin from the next one. the process of changing the natural course of a river to make it flow in a specific path so as to reduce possibility of flooding. the perimeter of river channel in contact with water
2. The hydrologic cycle map
Refer to Annex A 3. Factors affecting river energy River velocity Channel shape
Rivers with the same cross-sectional area but with different shapes have different velocities
The larger the wetted perimeter, the greater the friction, the lower the erosion, the slower the speed Channel Channel slope refers to the steepness or gradient of the the channel slope The steeper the slope (the higher the course), the greater the velocity of the river Three common types of patterns are the straight pattern, the meandering pattern Channel and the braided pattern pattern The lower the amount of friction, the faster the flow of water in the river Channel is uneven with items like boulders and vegetation Channel These items increase the amount of friction, thus decreases the velocity of the roughness water in the river River volume Size of Larger drainage basins have generally more tributaries that increase the volume of drainage water in the main river basin The larger the drainage basin, the greater the discharge Higher temperatures increase evapotranspiration rates and result in a lower discharge in the river Climate Higher precipitation result in more volume of water in the river to cause a higher discharge in the river More permeability of rocks increases the infiltration of water into the ground and reduces surface runoff Permeability Places with low permeability include concrete pavements in urban areas and places of rocks with asphalt roots When discharge exceeds river capacity, flooding occurs Presence of Vegetation intercepts and absorbs rainwater when it rains, increasing the vegetation infiltration of water and reducing surface runoff Elements of a hydrograph The graph of the amount of river discharge against time during a specific Hydrograph stormy period Rising and falling limb The gradient of the discharge increase from start of storm to peak of storm Lag time The time taken for the storm to reach the peak of the storm from the start Peak discharge The greatest discharge during any period of the storm
4. Erosion, depositional and transport methods a. Transport (TS3) Traction Saltation Suspension Solution
involves rolling and sliding of large particles like boulders along river bed moves bedload and small materials like pebbles downstream by bouncing transport of silt, clay, sand and other particles without the touching the river bed chemical action of river water in dissolving soluble rocks (limestone/CaCO3)
b. Erosion (CASH by vertical or lateral erosion) wearing down of a river bed and banks by grinding action of rock fragments carried by the river load carried by river is being broken as rocks collide with each other, becoming smoother and rounder in the process chemical action of river water in dissolving soluble rocks (limestone/CaCO3) loosening, breaking, dragging, tearing away and removing of rock particles from the river bed and banks by the sheer force of running water
Corrasion Attrition Solution Hydraulic action
c. Deposition
Why
When
Where
At the lower course, river velocity is low and energy level falls. The river is unable to transport its load and it will be dropped and deposited. Larger particles are dropped first as they require more energy to be transported When there is a decrease in river velocity, when floodwaters recede, or when a river enters a sea or reservoir or lake, there will be a significant drop in river energy, causing the river to lose its ability to transport its load. At the inner bend (convex bank) of a meander (slip-off slope) Floodplain when floodwaters recede At the river mouth where a delta is located
5. Landforms on rivers a. Erosional
Waterfall
Plunge pool
Gorge (it is a deep, narrow and valley with steep, almost vertical sides)
rocks of different resistance great force erode less resistant rocks faster hydraulic action (impact of water) change in gradient abrasion (rocks swirling at the base) sudden fall in height deepening the depth of the waterfall further hydraulic action excavated, enlarged and deepened by hydraulic action and abrasion results in a turbulent water at base of water deep depression known rock particles swirl about as a plunge pool further erodes the depression river flows flows to the edge of the cap rock of limestone through less water increases velocity a excavates a plunge pool at the bottom resistant rocks armed with rock debris vertical erosion backsplash at base of waterfall is faster than undercuts cliff face of less resistant sand and shale the wearing erosion of the cliff face away of the overhanging cap rock loses support and collapses sides of the continuation of the process cause the waterfall to retreat valley and form a deep, narrow and long valley known as a gorge
b. Erosional and depositional
Meanders (loops in the course of a river)
River cliffs and slip off slopes
Areas of regular-spaced deeper water pools and shallower water riffles Less friction in pools Greater velocity and erosive power More friction in riffles Lower velocity and more deposition Difference in velocities across channel Unequal pressure and energy distribution Currents in a river bank moves in a corkscrew manner, repeating a series of rotations Current from outer concave bank descends downwards Undercuts and erodes materials Continuous erosion causes some eroded materials are slumped down a river, forming a river cliff on the concave bank.
Continuous erosion and deposition accentuate Slight bends of a river Further erosion and deposition Bends are more pronounced Loops known as meanders form Some eroded materials are also carried along the bed up to inner convex bank Deposited there Continuous deposition makes the convex bank shallow Resultant slack water encourages further deposition A gently-sloping slip-off slope is built up
c. Depositional Floodplains (a wide low-lying plain found on both sides of a
and levees (natural river)
embankments found along river banks)
Heavy rain Amount of water will be more than the river capacity Water overflows its banks Floods surrounding areas Once out of the channel, there will be more friction
Ox-bow lakes (horse-shoe shaped lake)
Delta (a flat
alluvial platform found a a river mouth nearing a sea)
Velocity is reduced and energy decreases Deposition Larger, coarser and heavier materials are deposited at river banks and accumulate to form raised embankments (levees) Smaller, finer and lighter materials are deposited further away from the river banks and accumulate to form the floodplain Water now flows straight through the Continuous erosion of concave bank straighter river channel and deposition of the convex bank Instead of the cut-off abandoned Pronounced meander formed meander loop Two neighbouring banks get closer Deposits start to build up at both ends Narrow neck of land formed of cut-off Continued lateral erosion eventually Seals it off from the main channel erodes the narrow neck of land Cut-off becomes an ox-bow lake Outer banks merge Stabilised by vegetation or dried up River mixes with water upon entering sea Mass of alluvium built up from sea River velocity decreases and river loses bed and rises above the water energy forming extensive deposits deltas Deposits alluvium load of gravel, sand, A flat alluvium platform is silt and clay formed and obstructs the flow of The clay consolidates with salt water and water sinks to the bottom Water is forced to find another When tidal currents are not strong way around and hence overflows enough banks into distributaries And when coastal waters are shallow Levees built up enough Stabilised by vegetation
6. Channel management strategies (pros, examples, cons) Strategy i. ii. iii. iv. v.
Removes meanders
Description
Example
Reduces length Increase river velocity Realignment Flow away from an area more quickly (straightening Wash away sediments which have accumulated on the river of the river bed channel) vi. Deepens the channel vii. Channel capacity is increased to hold more water viii. Localised flooding is minimised i. Widening and deepening of river channel ii. Increases channel’s ability to hold water Reiii. Increases amount of surface runoff as more surface sectioning runoff can enter without flooding (widening and iv. Soil of river banks can be replaced with cement and granite deepening of the river v. Less friction between water, river bed and banks channel) vi. Increase rate of water flow away from a section of the river i. Built along river channel Gabions and ii. Divert flow of water to centre revetments iii. Protects banks from being eroded by force of running water iv. Reduces amount of sediment flow into the river
Vegetation planting and clearance
Disadvantage
i. ii. iii. iv. v.
Resectioning
Costly and labour intensive
Requires technological know-how Deters the growth of marine life like corals Aesthetically unpleasant and affect tourism Sediments may accumulate behind these structures and may lead to flooding, have to be maintained regularly May add stress to the banks and causes the banks to collapse
Singapore River has been extensively altered by widening and deepening the channels through dredging. This is an effective long-term measure. Revetments built in Jamuna and Megna Rivers in Bangladesh. Embankments of the Mekong River stabilised with mangroves planted along river by a joint initiative by Laos, Cambodia, Vietnam and Thailand.
Planting vegetation along river More roots of trees present Hold soil together firmly Improves stability of channel Minimal destruction to natural habitats
Strategy Realignment
For example, the Mississippi River in the USA has been shortened to up to 240km to reduce the threat of flooding.
Gabions and revetments
Vegetation planting Building of and clearance dykes
Disadvantage
Strategy Realignment
Resectioning
Gabions and revetments
Vegetation planting Building of and clearance dykes
Woody debris can become erosion agents and encourage flooding Continual build-up of sediments on river bed makes channel shallower and water levels to raise higher over the years Sediments have to be regularly dug up from the bed
7. Summarised pros and cons of dams (refer to Geography file) Pros Hydroelectric Power Generation Domestic Water Supply Flood Control Transport and economic value Recreation
Cons Silting Salanisation Destruction of habitats Resettlement of people Spread of diseases Destruction of delta downstream Water pollution
Annex A
1 2 Interception
Transpiration by plants
1
3 4
Reduces the amount of Water is taken through the roots to reduce volume of river as less water enters the river
water that reaches the river
Inputs
Outputs
Precipitation
1. River runoff
Stores and flows
2. Evaporation
1. Return flow
3. Transpiration
2. Interception 3. Surface water storage 4. Infiltration 5. Soil water storage 6. Percolation 7. Groundwater storage 8. Groundwater flow
TOPIC 5: COASTS 1. Wave terminology Crest Trough Wave height Wave length
The highest part of a wave formed between two troughs The lowest part of a wave formed between two crests The vertical distance between the wave crest and wave trough Horizontal distance between two wave crests or troughs
2. Coast profiles terms
offshore (not visible
foreshore (zone of contact
backshore (exposed all
even during low tides)
between sea and land)
the time)
high tide level low tide level
sand
coastline
shoreline
cliff
rocks
sea 3. Factors affecting wave energy
Duration of wind Speed of wind
Fetch Depth of sea
Wind effects The longer the wind blows, the larger the waves will be. Since waves are formed as a result of high wind velocities across the surface of the water they are proportionate. The higher the wind speed, the bigger the waves. Sea effects It refers to the expanse of sea that a wave travels through before reaching land. A larger fetch will allow the wave to gain more energy. Water particles in a wave are in a circular motion. A deeper sea would mean that the particles are able to move more freely as compared to shallow sea, where a lot of friction is encountered. Hence the deeper the sea, the less friction, the greater the size of the waves, and the greater the wave energy.
4. Erosion, depositional and transport methods a. Transport
Longshore drift (refers to the movement of sediments parallel to the coast by the action of waves reaching the coast at an angle)
Winds usually travel towards the coast at an angle. Prevailing winds cause the waves to hit the coast at an oblique angle. When the waves reach the beach, the waves break and topple over, causing surf containing sediments to run up the beach as swash. The surf then runs back down the beach as backwash perpendicular to the coast due to the influence of gravity. The sediments in the backwash are later being carried by a second swash. This continuous motion of swash and backwash result in transport of sediments in a zig-zag fashion by longshore currents.
b. Erosion (W.CASH) Wave refraction
Corrasion
Attrition
Solution
Hydraulic action
Wave refraction occurs when waves approach an irregular coastline in a parallel fashion. Wave energy is concentrated on promontories such as headlands, erosion occurs. Waves and rock debris lash against the base of cliffs, scouring and undercutting the rocks. Rock particles carried in the water knock against one another, reducing one another in size. The load is hence more rounded, evident from beach deposits. Rain water is a weak acid, and may be further acidified with acid rain. When it reacts with limestone containing calcium carbonate, it gradually weakens the whole rock structure, causing it to disintegrate. When waves surge into cracks and joints in rocks, air is trapped in the rocks and would be temporarily compressed. When the waves leaves the rocks, there would be a sudden expansion of the trapped air, exerting a force on the rocks. Alternate contraction and expansion weakens the structure of the rock overall, resulting in the disintegration of the rock.
c. Deposition
Where
Gentle waves Heavy load Erosion opposing factors *Indented coastline
Indented coastline Why
Gently sloping shorelines Source of beach sediments
Presence of vegetation Sheltered, less windy coast *Gently sloping shorelines *Source of beach sediments (e.g. headlands)
Wave refraction occurs Waves travel a larger distance to the bay compared to the headlands Dissipated wave energy encounters more friction and diverges at the beach as they spread Swash is stronger than backwash More deposition than erosion More active erosion occurs at the headlands
5. Landforms at coasts Landform
Sea cliff
Wave cut platform
Method of production When waves repeatedly pound against a rocky coast, rocks are weakened to form lines of weaknesses in the rock face A notch forms As a cliff continues to be eroded by waves, it retreats inland
Further eroded to form a sea cave The overhanging part of the cave eventually collapses with repeated pounding A cliff is formed Over time, a flat or gently sloping surface known as a wave cut platform is formed
Landform Headland
Bay
Beach
Berm
Method of production When waves approach coasts of differing alternating resistance, the less resistant rocks are eroded at a faster rate than the more resistant rocks
Rocks of different resistance builds Materials eroded form headlands up at headlands and bays together with materials carried by the Wave refraction at the headlands waves get deposited and accumulate at the bay cause wave energy to be dissipated at the bay Over time, a beach forms As constructive waves run up the Coarser heaver materials are hurled beach slope, it loses energy further up the beach slope and deposited Load is deposited there as the weaker backwash does not Swash is stronger than backwash have the energy to remove them, forming More materials deposited then the berm removed Finer lighter materials are carried During a storm, waves are stronger seawards by the backwash and deposited and beach sorting occurs near the water’s edge
Longshore drift
Spit
Tombolo
Notch
Cave Wave cut platform
Differing rates of erosion of rocks produce an uneven coastline Less resistant areas of rocks curve inwards to form bays More resistant areas of rocks protrude out from the coastline to form headlands
Prevailing winds Waves to hit the coast at an oblique angle Waves breaking obliquely at the shore move materials Along the shore in a zigzag manner known as longshore drift... Due to backwash and swash (more on 4a)
Spit formation
Abrupt change in the coastline causes the longshore drift to lose energy due to shallower waters
Sediments are deposited on the sea floor developing an under water ridge Over time, they extend further Currents are not strong enough to wash the deposits away Lie undisturbed
Hooking
The second most dominant pushes the tip landwards to give it its hooked appearance When the wind slackens, the spit continues to extend. The strong current carries the sediments out to sea and prevents the spit from extending further. Strong winds again pushes the end of the spit inwards to give its second hook
Tombolo formation
When an extension of a spit joins an offshore island to the mainland, and tombolo is formed
When waves have short wavelength and large The waves attack lines of wave height, they form destructive waves weaknesses by CSH (no A) Waves attack rocks of varying resistance by C, [elaborate each]. A, S and H along an exposed or uneven coast. Waves continually attack Bays and headlands form these weak rock joints Waves concentrate their energy on headlands A notch is formed at the Increased wave erosion form a cliffed headland base of the headland cliff Prolonged wave action The notch is gradually enlarged, forming a sea cave Over time further wave erosion As the steep cliff retreats due to continued along the cave may cause its roof erosion, undercutting the base of the cliff to collapse forming a steep cliff A gently-sloping land strewn with eroded face rocks called a wave cut platform develops.
Landform Arch
Stack Stump
Method of production The cave and wave up When the cave undercuts the base fully to the platform is slowly enlarged other side of the headland, it cuts through the and lengthened headland, forming an arch As the sides of the arch are being eroded by An isolated pillar of rock called wind and wave forces, the arch loses its a stack is left behind and support and collapses to the wave cut platform separated from the headland Continual erosion by strong winds and This stump is only revealed at destructive waves reduces the stack to a stump low tide and covered at high tide
6. Waves What happens as waves hit the
shore? 1) Waves approach the shore 2) Water depth generally decreases 3) Friction with seabed increases
Waves hitting a straight shore
4) Circular motion of waves is retarded
5) Waves slowed down 6) Length decreases 7) Crests bunch up 8) Wave height and steepness increases 9) Top of wave topples over 10) Surf runs up the beach as swash
Waves hitting an irregular shore
11) Percolates into the beach 12) Runs back down as less strong backwash
Energy Coastal waves Coastal process Ability Offshore Frequency Coast approach Association
No indentation Waves hit the shore at an oblique angle in direction of the wind Friction near the coast Waves get shallower Retards the speed of waves Waves break almost parallel to shore (longshore current) Transport of sediments increase
Headland Waves reach headland first before entering bay Wave refracted at headland concentrates energy there More intensive erosive power of C, A, S and H Bay When waves move towards the bay, it tends to curve away across the bay area Energy is dispersed Eroded material at the headland is deposited at the boy area
Constructive waves
Destructive waves
Low, resulting in low flat waves
High
Swash more powerful than backwash
Backwash more powerful than swash, surf pounds on sand but does not run far up the beach
Deposition
Erosion
Able to push material up the beach to form a berm at the top of the beach Low wave length and height Low (6-8 per minute)
Able to dig out material and carry it out offshore High wave length and height High (>10 per minute)
Gentle surging waves
Steep plunging waves
Gently sloping coasts
Steep sloping coasts
7. Coastal protection strategies Type
Strategy
Description
Example
Seawalls
i. Wall made of concrete built in front of a coast ii. Absorbs energy of the waves iii. Protects the coast against strong waves, especially during storms
Build at long stretches of coasts in England to reduce rate of erosion of land
Breakwaters
i. Granite materials acting as breakwaters are placed off and parallel to the coast ii. Creates a zone of shallow water between the coast and itself iii. Breaks the waves before it reaches the coast iv. Reduces wave energy
Singapore beaches like the East Coast Park and Siloso beach at Sentosa
Hard
Disadvantage Waves are redirected downwards to the base of the seawall as waves break Strong backwash wears away the base, weakening and collapsing it. Expensive, S$3 million per kilometre Unable to provide complete protection as some areas are still left unprotected Expensive, each breakwater is S$1 million
Groynes
Gabions
Stabilising coastal dunes
Soft
(Ridge of sand piled up by wind usually extending many kilometers and heights to 100 metres)
Planting mangroves on the shore
i. Low wall built perpendicular to the coast ii. Prevents materials from being transported away by longshore drift iii. As sediments accumulate at the side of the groyne i. Wire cages containing small rocks to form a wall ii. Protects the coast against erosion i. Ridge of sand piled up by wind ii. Provides protection to human property iii. Provides a habitat for many animals iv. Plantation of vegetation along coasts v. Roots trap and bind sand together, preventing sand from being blown inland i. They have prop roots that anchor trees firmly in the muddy soil ii. Bind loose soil and protect it from erosion iii. 2004 Tsunami showed that it helps
Groynes built at Sussex in the United Kingdom
Chichester Harbour in the United Kingdom
Omaha Beach in New Zealand Marram grass
2005 Malaysian government launched project to protect 4800 km of its coastline
The beach will not be replenished by materials carried by longshore drift Beach further down the coast may be eroded away Spoils the natural beauty of a coastal environment Can be easily destroyed by powerful waves during storms Wires rust easily Property development and recreational activities can damage the coasts Causes the sand to be easily blown inland Can easily cover nearby roads, farms and buildings Require cooperation of the people in the local area Have to be mindful not to let animals like goats enter the plantations
Type
Strategy i. Beach nourishment
ii.
i.
Soft Encouraging growth of coral reefs
ii. iii. iv.
Description Large amounts of sand are added to a beach that is being eroded When longshore drift removes sand from the coast, people bring in sand from other areas and deposit it onto the beach Masses of rock like substances calcium carbonate from living organisms Speed of waves approaching the coast is reduced Most of original energy of waves is lost Protect beaches against coastal erosion
Example 24 kilometres of the Miami Beach of the United States was renewed
Disadvantage
Pacific and Indian Oceans where water is warm and clear
This method usually lasts for only about 10 years. Beach quality sand is expensive Miami Beach project costed S$105 million Dynamite fishing, sand mining and land reclamation can destroy coral reefs Water pollution hinders growth of coral reefs Malaysia, for example, banned fishing in protected areas
CONCLUSION: MAPWORK AND PATTERNS 1. Map-work materials Long ruler Set square Protractor Calculator String Pencil Eraser 2. Formulas Vertical Distance
Gradient
(Make use of the contour lines, make sure line corresponds)
Horizontal Distance (Make use of long ruler and multiply with scale accordingly) Always express as a fraction or ratio with the numerator as 1 and denominator 3 sig. fig. if not exact
Dendritic
Trellis
Radial
Centripetal
depict
Main river resembles tree trunk and tributaries resemble branches
features
3. River and drainage patterns
River flows over areas of same rock types
Resembles pattern formed by bricks on a wall Rocks are made up of alternate bands of resistant and less resistant rocks
Move out from centrally elevated location River originates from the top of a steep hill, mountain or volcano
Rivers move towards of a focal point or depression Usually towards a volcano crater forming a crater lake
diagram
Opposite direction from radial, resembling spokes of a bicycle wheel 4. Common unique rivers
Centripetal rivers
Waterfalls formed by faulting
Rivers around Lake Toba in Indonesia
Victoria Falls along Zambezi River in South Africa
5. Weather patterns (describing from climograph)
Mean
Range/Distribution
Seasonality
Extreme months
Mean annual temperature Annual Temperature is ...with the hottest of climograph is high at temperature range hot throughout months in May and 26.8º C is low at 1.7º C the year... June at 27.5º C Mean annual rainfall The highest rainfall Rainfall is well ...with no dry shown is very high at in December at distributed... season 2343.7 mm 282.2 mm From the temperature and rainfall data, it can be seen that the climograph experiences a hot and wet climate throughout the year and is likely an equatorial climate.
Temperature Rainfall Identify
6. Weather descriptors
Mean temp. Temp. range Rainfall
High
Moderate
Low
Above 20ºC Above 15ºC Above 2000mm 1200 to 2000mm
10ºC to 20ºC 5 to 15ºC 750 to 1200mm
Below 10ºC Below 5ºC 250 to 750mm Below 250mm
7. Earthquake patterns
Oceanic Oceanic
Zones MidAtlantic
MidAtlantic East African Rift Valley
Continental Continental Oceanic Continental Oceanic Oceanic Continental Continental Transform Earthquake Boundaries
Himalayas
Volume drops
Himalayas Mariana
Andes
Mariana
Andes San Andreas
South North America America When Velocity drops
East African Rift Valley
Relation to factors Channel shape Channel slope Channel pattern Size of drainage basin Permeability of rocks Climate
San Andreas
Africa
When When When When
Arabian
IndoAustra Europe -lia
Nazca
Why there is an increase in wetted perimeter there is a sudden change in gradient the river flows into a calm lake or sea little or no rain enters a river
When the river flows across permeable rocks, allowing sinking in of water When the river flows across a desert when evapotranspiration rates are high
Pacific
Philippine Features
Floodplains Deltas
