Natural Environment

Waterfall – Niagara Falls

The Niagara Fallsare along the border between Canada and the United States and 51m high.

Waterfalls are where water descends vertically. Waterfalls are usually created by a change in rock type. As the river moves from hard rock to soft rock, erosion increases at the soft rock, creating a waterfall.
As the water falls over the waterfall it erodes the river bed and the bottom of the waterfall. This makes a plunge pool and causes some undercutting. The undercutting creates an overhang which will eventually become too heavy to be supported and collapse into the plunge pool. The whole process then starts again, which means the waterfall is constantly retreating upstream towards the source. As the waterfall retreats it leaves behind a gorge.
Gorge: A gorge is a deep sided valley left behind when a waterfall retreats

Benefits from living near waterfalls

  • Beauty
  • Tourism (Niagara, Victoria, Angel, Iguazu)
  • Jobs related to tourism e.g. guide, hotelier
  • Possible HEP potential

Possible Problems of living near waterfalls

  • Danger from fast flowing water (drowning)
  • Problems of creating transport links across or near falls (gorge)
  • Overcrowding an pollution from becoming a tourist location
  • Navigation problems up and down river

Delta – Ganges Delta in Bangladesh

When a river meets the sea its velocity suddenly reduces. This reduction in velocity means that much of the rivers load is deposited at the mouth of the river. If the river deposits quicker than the sea can erode then a delta starts to develop. Usually in areas of a small tidal range. Deposition can mean that the main river channel gets blocked, forcing the water to find alternative routes to the sea by making distributaries. Deltas have very fertile soil and tend to be excellent for farming. There are three types of delta; arcuate, cuspate and bird's foot.
Distributary: A distributary is a small river or stream that breaks off from the main river in deltas.
ADVANTAGES OF LIVING IN GANGES DELTA / DISADVANTAGES OF LIVING IN GANGES DELTA
  • Fertile land for farming, especially crops like rice
  • Plenty of water for fishing or aquaculture. This can feed families or provide an economic income.
  • Abundant drinking water
  • Water for cooking, washing, etc.
  • Tourism opportunities
  • Houses can be built on water and are then transportable and they do not flood
  • Good transport links, possible to trade
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  • Hard to make transport links by roads - cost of bridges
  • Areas are at constant risk of flood
  • Vulnerable to rising sea levels
  • Water is often dirty and polluted (industry, agriculture, sewers)
  • Mosquitoes are attracted to water (Malaria, Dengue)
  • Storm surges from tropical storms
  • Cost of building defences

Between 125 and 143 million people live on the delta,[citation needed] despite risks from floods caused by monsoons, heavy runoff from the melting snows of the Himalayas, and tropical cyclones. A large part of the nation of Bangladesh lies in the Ganges Delta, and many of the country's people depend on the delta for survival.[3]

It is believed that upwards of 300 million people are supported by the Ganges Delta, and approximately 400 million people live in the Ganges River Basin, making it the most populous river basin in the world. Most of the Ganges Delta has a population density of more than 200 people per km2 (520 people per square mile), making it one of the most densely populated regions in the world.

Approximately two-thirds of the Bangladesh people work in agriculture, and grow crops on the fertile floodplains of the delta. The major crops that are grown in the Ganges Delta are jute, tea, and rice. Fishing is also an important activity in the delta region, with fish being a major source of food for many of the people in the area.

In recent years, scientists have been helping the poor people of the delta to improve fish farming methods. By turning unused ponds into viable fish farms, and improving methods of raising fish in existing ponds, many people can now earn a living raising and selling fish.

Cyclones and flooding

In November 1970, the deadliest tropical cyclone of the twentieth century hit the Ganges Delta region. The 1970 Bhola cyclone killed 500,000 people (official death toll), with another 100,000 missing. The Guinness Book of World Records estimated the total loss of human life from the Bhola cyclone at 1,000,000.

Another cyclone hit the delta in 1991, killing about 139,000 people.

People have to be careful on the river delta as severe flooding also occurs. In 1998, the Ganges flooded the delta, killing about 1,000 people and leaving more than 30 million people homeless. The Bangladesh government asked for $900 million to help feed the people of the region, as the entire rice crop was lost.

Coral Reefs – Great Barrier Reef Australia

A coral reef is a line of coral polyp found in warm shallow seas. Polyp are tiny carnivorous (meat eating) animals. Polyps live in groups called colonies. A polyp has a mouth at one end. The mouth is surrounded by a number of tentacles. These tentacles resemble feet, which is how they get their name ('polyp' is a Greek word meaning 'many feet'). Polyps cannot move from their limestone homes. They mostly feed at night.
A polyp reproduces by dividing its own body to form two polyps, or by producing sperm and eggs. Each polyp builds a case of limestone around itself, using calcium from the water. It is like a house, with a floor and walls. This remains after it has died and forms a foundation for another polyp to build a house on, putting a floor on the roof of the old one. When these limestone formations increase, they are called a coral reefs.
Coral reefs are very delicate and need the following conditions to form:

  • Tropical sea conditions (between the two tropics)
  • Warm waters (ideal 25 degrees but must be over 18 degrees centigrade year round)
  • Clear water ( no sediment)
  • No pollution
  • Sunlight
  • Water less than 60 metres deep

Coral Reef Protection

  • Damaging fishing practices like dynamiting can be banned. It is important that this is enforced or the practices will carry on.
  • Conservation zones where tourists aren’t allowed or there numbers are restricted can be created.
  • Areas where coral reef cannot be farmed can be created
  • Fish stocks can be enhanced and quotas imposed on amount being caught
  • Sewage outlets can be moved downstream of coral reefs
  • Banning the dropping of anchors on coral reef.
  • Reduce the use of fertilisers near coral reefs
  • Finally one of the most important is educating people about why coral reefs are important and how we can protect them.

BENEFITS OF CORAL REEFS / HOW CORAL REEFS ARE BEING DAMAGED
  • They support 25% of marine species (about 1 million species of plants and animals)
  • They protect coastlines from erosion
  • They form as a natural barrier against tropical storms and even tsunamis (they can absorb energy).
  • Act as natural recycling agent for carbon dioxide from sea and atmosphere
  • They contribute material to the formation of beaches (eroded coral reef)
  • They are source of raw material (coral for jewelery and ornaments)
  • Many species are being found to contain compounds useful in medicine.
  • They benefit the tourism industry because many people like to dive and snorkel over coral reefs
  • They provide important fishing grounds
  • The global value of coral reefs in terms of coastal protection, fishing and tourism has been estimated at $375 billion.
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  • Rising sea levels mean that the depth of water above coral reefs is increasing. This means that in the future many coral reefs will not receive enough sunlight to survive.
  • Increases in the global climate means that many corals are being bleached. Coral reefs are extremely sensitive to changes in temperature and can bleach (die and turn white) even with only small increases.
  • Hurricanes. Although coral reefs act as a natural defence against tropical storms, they can be severely damaged during tropical storms.
  • Fishing techniques like dynamite, cyanide and trawling can damage corals. Corals are sensitive and take hundreds and thousands of years to grow.Damaging fishing techniques therefore can cause long term damage.
  • Deforestation. As areas of land are deforested, especially in the tropics (Indonesia, Thailand, Philippines) there is greater surface run-off and more sediment enters the rivers and is ultimately discharged into the sea. The increased sediment reduces visibility and means less sunlight reaches the coral.
  • Overfishing. Not only do damaging fishing techniques damage the coral but also overfishing. Coral reefs have very delicate food webs and if you remove elements of the food web, it can upset the balance of the reefs.
  • Pollution. The growth of urban settlements and tourist developments, as well as increased coastal traffic can also cause pollution to reefs.
  • Tourism. Tourism can damage reefs in many ways. Anchors from tourist boats can damage reefs. Motor boat engines can kill animals. Divers can touch and damage coral and tourist developments can release pollution.
  • Marine trade. There are many products, like coral, turtle shells, star fish and sea shells that get removed from corals and sold. This removal of coral and animals damage the reefs.

Tropical Rainforest – Amazon Rainforest, Brazil

Distribution
Tropical rainforests are found on or near the Equator (roughly between 28 degrees north and south). The main concentrations of tropical rainforests are:

  • The Congo Basin in central and west Africa
  • The Amazon in Brazil, Peru, Bolivia and Ecuador
  • SE Asia (Malaysia, Thailand, Vietnam, Indonesia and the Philippines)
  • Madagascar
  • North east Australia
  • Southern India and Sri Lanka
  • Central America

Deforestation rates vary massively, one reason is the inaccessibility of many of the forests and the way people classify deforestation. However, it is claimed that now only about 5% of the earth's surface is covered in tropical rainforests, compared to nearly 15% 50 years ago. Many people believe that tropical rainforests could disappear this century.

Tropical Rainforest Climate

Because tropical rainforests are close to the equator, they have very similar climates all year around. Their temperature is constant at between 25 and 30 degrees Celsius. They also receive rainfall all year around, although the monthly amounts may vary slightly. Tropical rainforests normally experience convectional rainfall. This is because they are close to the equator where temperatures are hot. The hot temperatures warm up the land, causing evaporation and transpiration and then convection. Not only is the weather similar between months, it is also very similar between days. Days will start of warm and then the temperature and humidity will build up. By the afternoon the air is saturated and tropical rainforest normally experience intense rainstorms. Because tropical rainforests are near to the equator the hot air rises causing low pressure.

Importance of Tropical Rainforests / Reasons for Deforestation / Problems Caused by Deforestation
  • Biodiversity: Although rainforests cover only about 5/6% of the world's land mass, it is estimated that they could contain up to 50% of the world's biodiversity. This is potentially up to 15 million species.
  • Photosynthesis: Tropical rainforests are often referred to as the 'lungs of the earth' and convert large amounts of the greenhouse gas carbon dioxide back into oxygen. It is estimated that the Amazon rainforest alone produces about 20% of the earth's oxygen.
  • Flood control (interception, transpiration): Rainforests are an excellent natural measure to reducing flooding. There is leaf cover in rainforests all year so interception continually happens, extending rivers lag time. All vegetation uptakes water and transpires it.
  • Control of soil erosion: The root systems of trees and shrubs hold the very thin soil of rainforest in place. If trees are removed then both erosion of topsoil and landslides are more likely
  • Source of nutrients to humus layer in soil: The topsoil in rainforests is very thin and relies on the nutrients provided by rotting plants and animals. Because of the rainforests climate, there is a constant supply of leaf litter.
  • Medical remedies: Rainforests have been the source of many of today's drugs, including the basic ingredients for the hormone contraceptive pill, quinine (a anti-malaria drug) and curare (a paralysing drug).
  • Cash crops and agricultural products: Yam, coffee, rubber, mango, banana, sugarcane, cocoa and avocado were all first discovered in rainforests.
  • Ecotourism: With people becoming ever more environmentally conscious and looking for increasing adventures, ecotourism to rainforests is increasing. This not only helps protect rainforests, but creates income for locals. Ecotourism is an important income to countries like Costa Rica and Belize.
  • Home to indigenous groups: Although the number of indigenous groups and people have declined rapidly since colonisation in South America, it is estimated that there are still over 200,000 people that consider the Amazon their home.
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  • Cattle Ranching: As the world's population gets bigger and richer, the demand for meat is increasing. To rear the cattle increasing tracts of the rainforest are being cleared to make pastures for grazing.
  • Subsistence Farming: Because of the large amounts of poor people that still live in tropical areas, subsistence farming is still widespread. Because rainforest soil loses its fertility quickly after deforestation, the most common form of subsistence farming is slash and burn. With growing populations this method of farming can cause widespread deforestation.
  • HEP: Many of the world's great rivers flow through rainforests e.g. the Amazon. These great rivers often have the most HEP potential. Unfortunately when a dam and reservoir are built it causes damage during construction, but also floods large areas.
  • Mining: With an ever increasing demand for the world's natural resources, countries and companies are looking at increasingly isolated locations, places like rainforests and Antarctica. The rainforests are believed to have many resources including metals and fossil fuels beneath their soils. Gold mining can be particular damaging as mercury is used in its extraction and often runs off into rivers.
  • Road building: Building new roads like Trans Amazon highway from Brazil to Bolivia not only causes deforestation itself, but its also opens up new areas to urbanisation, mining and farming causing further deforestation.
  • Urban growth: With the world population increasing as well as rates of urbanisation increasing many cities like Manaus in Brazil are growing rapidly causing deforestation.
  • Population growth: As populations grow, particularly in countries like Brazil, Peru, India and Vietnam that contain rainforests the demand for land increases, both to grow food and to live).
  • Plantations: Primary products are often seen as an income source for LEDCs, many of who have large areas of rainforest. At the same time with fossil fuels running out, alternative fuels sources are been searched for including biofuels e.g. Palm oil. This has lead to widespread deforestation in countries like Malaysia and Indonesia to plant cops like palm oil.
  • Timber (hardwoods): Hardwoods like mahogany and teak that take hundreds of years to grow are still in high demand to make things like furniture. The extraction of these trees can kills trees around them. Also many countries like China are also demanding large amounts of normal timber that are not always taken from sustainable sources.
  • Hunting: Hunting takes two forms, one form is for bushmeat to feed families and enough the sale of animals either alive e.g. parrots or dead for their skins e.g jaguars.
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  • Flooding: Flash floods become more common after deforestation because there is less interception and less root uptake and transpiration. As such rainwater reaches the ground quick, saturating it and causing surface run-off and potential flooding.
  • Landslides: By removing trees and vegetation, you are making the soil less stable. Combine this with saturated ground and the likelihood of floods increases.
  • Biodiversity loss: Because all the species that live in the rainforest are not known it is hard to calculate species loss. However, scientists believe that 1 mammal or bird extinction can be extrapolated to approximately 23,000 extinctions.
  • Reduced photosynthesis: As more and more trees are removed the rate of photosynthesis reduces, releasing more carbon dioxide into the atmosphere and contributing to the greenhouse effect.
  • Silting of rivers: With increased flooding and surface run-off moil soils and silt is washed into rivers, this can not only change local ecosystems (water temperature and clarity) but can also reduce the depth of rivers making navigation harder.
  • Silting of seas and oceans: With the increased frequency of flooding and landslides more silt gets washed into the oceans. The increased amount of silts reduces the transparency of the sea reducing the light reefs receive and the temperature of the water. Increased silt can also block important shipping lanes.
  • Breaking of nutrient cycle: The top soil of rainforests is very thin an receives the majority of its nutrients from rotting flora and fauna. Be removing trees you also remove animals and therefore the source of the soils nutrients. With increased erosion the top soil (humus) layer is quickly washed away.
  • Sandification/desertification: Because rainforest soil loses its fertility very quickly after deforestation it quickly becomes hard to grow any vegetation on it, leading to sandification and possibly desertification.
  • Loss of indigenous homes: By clearing rainforests you are obviously destroying the homes of indigenous groups. But also moving close to indigenous groups can spread disease and alter local culture and traditions.
  • Reduced rainfall: Deforestation can lead to reduction in local rainfall because less water is intercepted and transpired from vegetation into the atmosphere reducing the formation of clouds and rainfall.

Deserts – Sahara Desert, Northern Africa