Amazon and Rio Negro report, by Megan Bijl
The estuary of the Rio Negro in the Amazon is a beautiful sight. The Rio Negro has a black/dark brown colour and the Amazon is white coloured. Both rivers differ in water composition. Some people associate the catchment area with untouched wilderness, populated by the native community.
Characteristics:
Length: 1000 km
Width: Varying from 1 km in the river to 100 km at the mouth
Catchment area: 6 million km2
Temperature: + 26o C
Rainfall: + 2300 mm per year
Flow rate: Varies from 75.000 m3/s to 212.000 m3/s
Acidity: Ranging from pH 3,6 to 5,8 (depending on the season)
Climate: Tropical
Note: Most powerful river in the world
Causes of disruption of the ecosystem
· Mining of ores
· Discharge of mercury into the water (mercury is used in the purification of gold)
· Rubber production
· Coca production
· Deforestation to make room for industries
Cuases of deforestation and threats to the catchment area
· Building of factories
· New infrastructure, mainly railroad an roads
· Expansion of residential areas
Economy
· Due to the great debts owned by Brazil to other countries, like the United States, the economy and payment of the debts have a higher priority then nature and the environment.
Abstract
Introduction
The Rio Negro is a large tributary of the Amazon, which is the most powerful river of the World. The Amazon is well known for its surrounding bio-geographic area; the tropical rain forest. The catchment basin of the river is as big as the continent Australia, six million square kilometres and the rain forest grows in a moist tropical climate. The average temperature is 26 degrees Celsius and the average rainfall per year is 2300 millimetres. The Amazon area, also called Amazonia, is the richest tropical nature reserve of the world, but unfortunately it is also the most threatened one. Especially during the last twenty years a lot of things were destroyed locally; among other things by deforestation.
The Rio Negro River
The Rio Negro is a tributary of the Amazon and forms the northern part of the catchment basin. The river has a length of a thousand kilometres and rises in the southeast of Venezuela, flows through Colombia and finally discharges in Brazil in the Rio Amazon. The Rio Negro is named after the dark brown/ black coloured water. The cause of this is the fast demolition of organic material and the high degree of acidity changing from pH 3,6 to 5,8 (depending on the season). The river has a water composition that’s comparable to freshwater. The catchment basin has fewer minerals in the ground and the dynamics of both rivers are unprecedented great. In the wet season from April till October the water level can rise eight meters above sea level. That is unprecedented high, because near the rise, the river’s width is only one kilometre and in the mouth well over 100 kilometres. A level rise of eight metres is therefore very high and the flow rate varies from 75.000 m3/s to 212.000 m3/s. It is an asset that the river hasn’t got any mineral riches, so the greater part is still intact. And some parts were designated nature reserves.
The Amazon
The estuary of the Rio Negro in the Amazon is a beautiful sight. The Rio Negro has a black/dark brown colour and the Amazon is white coloured. Both rivers differ in water composition. Some people associate the catchment area with untouched wilderness, populated by the native community. A fact is that the downstream part is rich on reserves like ores, mineral oils, an immense amount of tropical wood and, most important, the wildlife. The catchment area, however, is increasingly disrupted and this is not likely to stop in the future. The most important causes for these disruptions are gold mining, rubber production, ore mining, oil industry, coca production, tropical deforestation, tourism and some work of arts in the tributaries. Gold that is found in the riverbanks is purified with the heavy metal mercury and flows straight into the surface water. For the industry large areas of the forest disappear to make space. The catchment area of the Amazon has the biggest supply of iron and tin ore of the world. To purify these ores, like manganese, bauxite, nickel, copper and zinc, these areas were in a short time changed and destroyed. Factories, railways, new roads, residential areas are all developments with great threats for the surroundings.
Exploitation of the catchment area
The biggest part of the catchment area lies in the federal state of Brazil. Until 1985 Brazil had a military regime and the present civil government has great debts. North America has given tremendous loans (in 1987 VS $ 100 billion) and the support of the IMF (International Monetary Fund) and other foreign banks is very necessary. Because of the enormous foreign debts the economic have a higher priority than the environmental and the whole forest shrinks faster and faster. With satellite surveys it is all ready shown that it is still going downhill, in spite of the great international pressure. The dimensions of the tropical rain forest are still big and still economic interest prevails over the environmental interest. Unfortunately South-America knows too much poverty, as a result of which it will take a long time for the tropical rainforest will regain its original state.
The river basin of the Amazone River and the Rio Negro River
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