Tuesday 4 October 2011

top ten amazing rivers and their fact


Top Ten Longest Rivers In The World

#1 - Nile (4,180 miles)

The longest river in the world, the river Nile, starts at the Tributaries of Lake Victoria, Africa and runs into the Mediterranean Sea.

·         The length of the Nile River is approximately 6650 kilometres (4132 miles). It is believed to be the longest river in the world.

·         Located in Africa, the Nile River lies in the following countries: Kenya, Eritrea, Congo, Burundi, Uganda, Tanzania, Rwanda, Egypt, Sudan and Ethiopia.

·         The Nile River has huge significance in regards to Ancient Egypt. Most of Ancient Egypt’s historical sites are located along the banks of the Nile River including cities such as Luxor and Cairo.

·         In 2004, the White Nile Expedition became the first to navigate the entire length of the Nile River. The expedition began in Uganda and finished in Rosetta, taking four months and two weeks to complete.

·         The Nile Delta in Northern Egypt is where the Nile River drains in to the Mediterranean Sea. It is around 160 kilometres (100 miles) in length and spreads out over 240 kilometres (149 miles) of coastline. It is rich in agriculture and has been farmed for thousands of years.

·         Around 40 million people (half of Egypt’s population) live in the Nile Delta region.

·         In 1787, the famous Rosetta stone was found in the Nile Delta in the city of Rosetta. This Ancient Egyptian artifact played a key role in modern understanding of Egyptian hieroglyphics.

·         The Aswan High Dam was built in 1970 to help regulate flooding of the Nile River. Before the Aswan Dam was built, years that featured high levels of water could wipe out crops while years of low level water could produce famines and drought. The dam helps control these water levels.





#2 - Amazon (3,912 miles)



Amazon Rainforest, River and Drainage Basin Vital Statistics

Geography

Location: The Amazon rainforest lies within an area comprising about one-third of the South American continent, defined by the watershed (drainage area) of the Amazon River. It occupies a region in the northern portion of the continent, from central Brazil and Bolivia up to the northern coasts of Venezuela and the Guyanas to Central America.
Size: The Amazon River basin is the world's largest drainage basin (watershed), measuring 2,375,000 square miles (6,151,000 square kilometers), about 40% of the South American continent. Compared with other regions, this is about four-fifths the size of Australia, over three-quarters the size of the continental United States, or 25 times the size of the United Kingdom. From west to east, the river basin measures approximately 3,600 kilometers (2,240 miles, the distance from Los Angeles to Washington DC York is 2,300 miles) west to east and 2,500 kilometers (1,550 miles) north to south.
Area covered by water: 110,000 square kilometers (dry season) to 350,000 square kilometers (flood season)
Elevation: Most of the Amazon River basin upon an extremely flat alluvial plain, less than 100 meters (328 feet) above sea level. the highest point within the biome (tropical rainforest) is Neblina peak (3,040 meters; 9,974 feet) in northern Brazil. (Higher regions transition into different habitat types.)

River

Location: The Amazon River flows west to east across South America, approximately along the equator
Source: Nevado Mismi in the Andes mountains of Peru, 190 kilometers (120 miles) from the Pacific Ocean (elevation 5,200 meters; 17,000 feet)
Mouth: mid-Atlantic coast of northeast Brazil
Length: 6,437 kilometers (4,000 miles)
Navigable length:
ocean steamers (+ 3000 tons) to Manaus (1,600 km; 1,000 miles)
small ocean vessels (< 3,000 tons) to Iquitos (3,700 km; 2,300 miles)
small riverboats to Achual (4,480 km; 2,786 miles)
small boats to the Pongo de Manseriche, just above Achual Point
during flood season the total length of navigable waterway throughout the river basin can exceed 2 million kilometers.
Max depth: 100 meters (300 feet)
Max width: about 2 to 10 kilometers (1 to 6 miles)
Width at mouth (of the delta): 300 miles
Flow rate: 184,000 cubic meters (6.5 million cubic feet) per second in the rainy season
Flooding: Depth varies plus or minus 40 feet due to annual floods
Tidal bore: Depth varies plus or minus 12 feet (3.7 m high) to about 800 km (500 miles) upstream (locally called pororoca)
Longest tributary: 3,379 km, Rio Purus, Peru to Brazil
Biggest blackwater river: Rio Negro
Proportional areas of rainforest in each country:Brazil = 62.4%, Peru = 16.3%, Bolivia = 12.0%, Colombia = 6.3%, Ecuador = 2.1%

Climate

Temperature: 70° to 90°F during the day, 60° to 70°F at night (Mountainous areas on the edge of the Amazon Basin can be considerably cooler.)
Rainfall: 70 to 100 inches of rain yearly (e.g., Los Angeles = 7 inches per year. London = 30 inches per year)
Cloud cover: 40% average

Conservation

Rate of destruction: 18,000 square kilometers per year on average since 1990 in Brazil alone.
Total area now clearcut: 500,000 square kilometers (about a fifth of the total area)
Extinction rate: an average of 137 species per day (50,000 per year)
Threats: slash and burn farming, ranching, logging, mining, urbanization, road-bulding

Economic value of one hectare of rainforest in the Peruvian Amazon* (RAN)
Sustainably managed for fruit, latex, and timber harvest: $6,820 per year
Commercial timber harvest (unsustainable): $1,000
Cattle pasture: $148

People

Total population: 20 million people
Urban population: 50 to 60%
Employment: farming and ranching (about 20%), gold mining and prospecting, rubber tapping, fishing, hunting/gathering, oil industry, lumber industry, tourism and service industries
Ethnicity today: 400 different ethnic groups; 1.5 million people
Ethnicity before arrival of Europeans: 2,000 groups, 7 million people
Percentage of tribes with less than 1,000 people: 75%
Number of languages and dialects: about 200


#3 - Mississippi (3,710 miles)


The Mississippi river's source begins at the Source of Red Rock, Montana and ends in the Gulf of Mexico.

#4 - Yangtze (3,602 miles)

The Chang Jiang or Yangtze river begins at the Tibetan plateau, China and leads to the China Sea.

#5 - Ob (3,459 miles)

The river Ob starts at the Altai Mountains, Russia and ends at the Gulf of Ob.

#6 - Huang He (2,900 miles)

The Huang He or Yellow river, on of the longest rivers in the world, begins its journey in the Eastern part of the Kunlan Mountains, West China and ends in the Gulf of Chihli.

#7 - Yenisei (2,800 miles)

The Yenisei begind in the Tannu-Ola Mountains, western Tuva, Russia eventually running to the Arctic Ocean.

#8 - Paraná (2,795 miles)

The Paraná river in Argentina starts its journey from the Confluence of Paranaiba and Grande rivers and terminates at the Río de la Plata.

#9 - Irtish (2,758 miles)

The Irtish river's source lies in the Altai Mountains, Russia and joins the Ob River over 2,700 miles away.

#10 - Zaire (2,716 miles)

The last entry on our list of the top ten longest rivers in the world is the Zaire or Congo river, which starts at the Confluence of Lualab and Luapula rivers, Congo and runs into the Atlantic


'Amazon, not Nile, is longest river'


Brazilian scientists say they have established that the Amazon, not the Nile, is the longest river in the world. The precise length of the river is not easy to calculate and depends on correctly identifying the source and the mouth.
The Amazon is recognised as the world's largest river by volume, but has generally been regarded as second in length to the River Nile in Egypt.

The claim follows an expedition to Peru that is said to have established a new starting point further south. It puts the Amazon at 6,800km compared to the Nile's 6,695km, BBC News website reported.

The new claim in Brazil follows an expedition by scientists which is said to have discovered a new source for the Amazon in the south of Peru and not the north of the country as had been thought for many years.

While the exact location has yet to be confirmed from two choices, scientists say either would make the river the longest in the world.

Guido Gelli, director of science at the Brazilian Institute of Geography and Statistics, told the Brazilian network TV Globo that on Saturday that it could already be considered as a fact that the Amazon was the longest river in the world.

The Amazon is now said to begin in an ice-covered mountain in southern Peru called Mismi.

Researchers travelled for 14 days, sometimes in freezing temperatures, to establish the location at an altitude of 5,000m.

The research was co-ordinated by the National Geographical Institute of Peru, with the help of their colleagues in Brazil.

There has been a healthy academic debate over the world's longest river for some years and the claim from Brazil may not go unchallenged.

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