south america's environmental geography
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South America's Environmental GeographyTRANSCRIPT
South AmericaEnvironmental Geography
• Introduction & Rural environmental issues
1
• Urban environmental challenges2
• Western mountains & Eastern shields3
• River basins & Lowlands4
• Climate patterns5
• Latin America & Global warming6
Challenge to S.A. goverments
The need for economic
development
The need for environmental conservation
Rural environmental issuesDeclining forests & Degraded farmlands
Deforestation & Biological
loss
Agriculture
Wood export
Search for gold
Permanent settlement
Grassification
▪ Definition: The conversion of tropical forest into pasture
▪ A practice that contribute to forest loss
▪ In Southern Mexico, Central America, Brazillian Amzon, development policies encouraged deforestation to make room for cattle
▪ However, ranching in remote areas is seldom economically self-sustaining
Problems on Agricultural lands
Pressure to modernize agriculture causes many environmental problems
▪ Adopting new hybrid species of corn, beans, etc -> native species disappearance -> genetic diversity erosion
▪ Chemical fertilizers & pesticides -> contaminating soil & water; causing severe health issues
▪ Failure/lack of soil conservation measures -> soil erosion & fertility decline -> production decreased
▪ Urban expansion claims much of the best farmlands
Urban environmental challenges
▪ Latin America’s most pressing environmental issues are found in its urban areas
▪ Mexico City is a good example of the kinds of environmental challenges facing modern Latin American cities
A picture of Mexico City taken by BBC
I. The Valley of Mexico’s Environmental Problems
The Valley of Mexico
▪ Cradle of Aztec civilization
▪ Site of Mexico city with a pop. of 18 mil people
▪ Has the ideal environmental settings to build a city, though it’s currently severely degraded
Mexico City’s most pressing problems
▪ Air quality
▪ Water pollution
▪ Subsidence (soil sinkage)
1. Air Quality
▪ A major issue since the 1960s
▪ Caused by city growth, number of cars & physical settings
▪ Pollution high enough to cause a gray cloud hanging above the city
The city’s settings play a major role in creating pollution and enlarging it
▪ The city sits in a bowl 2250 meters above sea level
▪ A layer of warm air traps a layer of cold air near the surface (thermal/temperature inversion)
▪ The cold air layer is filled with pollutants
▪ Cause a great deal of troubles for the inhabitants
Steps taken to improve the situation
Starting from 1980s: reduce emissions from factories and cars
▪ Unleaded gas available for the 4mil cars in the metropolitan areas
▪ Cars for Mexican markets must have catalytic converters
▪ Worst polluting factories closed
▪ Program restricting driving was expanded
▪ Expanded low-emission Metrobus system, build suburban train system
=> No longer ranks in the top polluted cities in the world, cut pollutants by half
2. Water Pollution
▪ One of the most relentless environmental problems
▪ Most water – which used to fill the valley in lakes – were drained for agriculture
▪ Less surface water => more wells were dug to use the basin’s fresh water aquifer
▪ Evidenced that the aquifer is being overdrawn and at risk of contamination
▪ To reduce reliance on underground water, the city pumps water from 160km away
3. Subsidence (soil sinkage)
▪ Mexico is sinking, as the metropolis pumps water from its aquifer
▪ Impacted the whole city throughout:
- Building foundations destroyed
- Water and sewer lines rupture
- Damaged landmarks
▪ Water no longer being pumped from the city => slowed the sinking to 2.5cm a year compared to 50cm at its worst
Impact of sinkage
The Cathedral leaning to the left after centuries of subsidence
Cracks in building foundations
II. Ongoing Urban Challenges and Responses
▪ For most Latin Americans, most pressing environmental problems = air pollution, inadequate water and garbage removal
▪ They live better than their counterparts in Asia and Africa but still need expensive remedies for env. problems
A squatter settlement in Mexico City
Industrialization = major cause for pollution, but government tends to go easy on enforcing env. laws
=> in the worst cases, it poses a serious threat to people and the environment
Cubatão, São Paulo, Brazil, once called the valley of death due to pollution
▪ Not far from Cubatão is Curitiba, the capital of Paraná state – a model city also called the “Green City” for its planning decisions
▪ Significantly less polluted than other similar sized cities
▪ City planners built drainage, canals for floodings, set aside other areas as parks early during the 1960s
▪ Public transportation = top priority
▪ Low tech but effective recycling program
=> Designing with nature makes sense both ecologically and economically
Curitiba City, Brazil
Western Mountains and Eastern Shields
▪ The Andes
▪ Relatively young, 5,000 miles long; 30 peaks over 20K feet
▪ Active volcanism and earthquake
▪ Contain valuable metals and minerals
Western Mountains and Eastern Shields
▪ The Andes is divided into northern, central and southern component.▪ The northern Andes: 3
mountains ranges
Western Mountains and Eastern Shields
Altiplano: treeless, elevated plain in Peru and Bolivia, the floor ranges from 11,800 feet to 13,000 feet
Two high-altitude lakes: Lake Titicaca and Poopó
Western Mountains and Eastern Shields
▪ The southern Andes: the highest peaks, Aconcagua, 23,000 feet, mountains are lower
Western Mountains and Eastern Shields
The Uplands of Mexico and Central America
▪ The Mexican Plateau and the Volcanic Axis of Central America: The most important Latin America uplands
▪ Most major cities and population found her
Mexico City
Guadalajara Puebla
Western Mountains and Eastern Shields
▪ Rich volcanic soils, domestic and export crops
▪ Agriculture land that yield beef, cotton and coffee
Western Mountains and Eastern Shields
▪ The Shields: 3 major shields▪ The Guiana shield
▪ The Brazilian shield: the largest shield, more important,rich of fertile red soils, elevated basins ( city of São Paulo-largest urban conglomeration in SA), commercial agriculture
Western Mountains and Eastern Shields
▪ The low-lying Patagonian shield: treeless, covered by scrubby steppe vegetation, offshore oil production
River Basin and Lowlands
Within these basins are vast interior lowlands:
▪ The Llanos
▪ The Amazon lowlands
▪ The Pantanal
▪ The Chaco
▪ The Pampas
Settlement
Natural resources
Intense economic activities
Amazon Basin
▪ Geography:
- The largest river system in the world by volume and area, the second longest by length (2.4 million square miles)
- There is no real dry season
The Amazon
contributes 20% of
all freshwater
discharged into
the ocean.
Amazon Basin
▪ Amazon Basin draws from 8 countries
An ideal network to integrate the northern half of South America
Population
▪ Most of the older settlements are found on the floodplain, where natural levees reach heights of 20 feet (6 meters)
▪ Roughly 15m people (about 8% of the country’s total population) live in Brazilian Amazon
PLATA BASIN
▪ The region’s second largest watershed
▪ Make up from 3 major rivers:
+ The Parana
+ The Paraguay
+ The Uruguay.
▪Economically productive:
especially soybean production
The Chaco (arid area)
The Pantanal
(inundated lowlands)
Support livestock
Contains major dams: Itaipu - region’s largest hydroelectric plant
-Enhance Panara River’s capacity for barge and boat traffic.
Orinoco Basin
▪ The third largest river basin
▪ Located in northern South America
Population
North of the basin: 90% of Venezuela’s population
The Industrial developments between Ciudad Guayana and Ciudad Bolivar:
many cities located.
Llanos (grasslands)
▪ Support large cattle ranches
▪ Become a dynamic area of petroleum
production for Colombia and
Venezuela.
Climate patterns
In tropical Latin America averagemonthly temperatures show littlevariation. Precipitation pattern dovary, however, and create distinctwet and dry seasons.
▪ The tropicallowlands classifiedas tropical humidclimates thatsupport forest orsavanna, dependingon the amount ofrainfall.
▪ Extreme aridity region’s desert climates
▪ Midlatitude climates, with hot summers and coldwinters, prevail in Argentina, Uruguay, and parts ofParaguay and Chile.
The Andean range over the province of Santa Cruz – Argentina.
Altitudinal Zonation
▪ Altitudinal zonation has practical applications.
▪ The environmental lapse rate.
The concept of altitudinal zonation is most relevant for the Andes, the highlands of Central America, and the Mexican Plateau.
El Nino
▪ Occurs when a warm Pacific current arrives along thecold coastal waters of Ecuador and Peru in December,around Christmastime
▪ Happens every few years
▪ Produces torrential rains, signaling the arrival of an ElNino year
▪ El Nino’s impacts.
Global Warming
Global warming - one of the dominant issues in Latin America
8% of the world’s population
▪ 6-8% of global greenhouse emissions
▪ Rate of greenhouse emissions growth : lower than in all other regions, except for Sub-saharanAfrica
Reasons for low greenhouse emissions growth rate
▪ Lower average energy consumption
▪ Higher reliance on renewable energy
▪ Greater dependence upon public transportation
Highland areas :Higher temperature and Lower rainfall
Retreat of Andean glaciers
Retreat of Andean glaciers
Dengue fever
Dengue is now widespread in more than 100 tropical and sub-tropical around the world
• Impact the frequency and strength of El Nino cycles => Increased flooding in Western South America=> Declining fishery off the coast of Peru and Chile
• Increasing hurricane intensity
Several unprecedented weather-related events in the recent past
• Intense rainfall in Venezuela (1999, 2005)• Amazon drought (2005) in Brazil• Hailstorms in Bolivia (2002) and Greater
Buenos Aires area (2006)• The devastating hurricane Katrina in 2004
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