| Amaze your friends
and colleages with some Amazon trivia compiled by Project Amazonas.
Who knows, it might even win you a million $$ someday on some hokey
gameshow! The
Amazon River is the worlds greatest river.
The Nile River of Africa may be slightly longer than the Amazon,
depending on the channels measured, but for many other reasons the
Amazon River is the undisputed greatest river on the planet, in
solar system, and perhaps even in the entire galaxy (we won't try
and make a claim for the entire universe!).
If size
is important to you...
The average discharge of water into the Atlantic Ocean by
the Amazon River is approximately 175,000 M3 per second, or between
1/5th and 1/6th of the total discharge into the
oceans of all of the worlds rivers!!! This discharge is 4-5 times
that of the Congo River, and 10 times that of the Mississippi River.
The Rio
Negro, a tributary
of the Amazon, is the second largest river in the world in terms
of water discharge, and is 100 meters (over 300 feet) deep and 14
kilometers (~9 miles) wide near its mouth at Manaus, Brazil.
Raindrops
keep falling on my head!
Average rainfall across the whole Amazon basin is approximately
2300 mm (or ~7.5') annually. In some areas of the northwest portion
of the Amazon basin, yearly rainfall can exceed 6000 mm (almost
20')!
Where
does all that water go? All of the water
that is discharged into the Atlantic Ocean is actually only about
1/3rd of the water that falls into the Amazon basin as rain. Where
does the other 2/3rds go? Up to half of the rainfall in some areas
may never reach the ground, being intercepted by the forest and
re-evaporated into the atmosphere. Additional evaporation occurs
from ground and river surfaces, or is released into the atmosphere
by evapo-transpiration from plant leaves. All of this evaporated
moisture re-enters the water cycling system of the Amazon, and a
given molecule of water may be "re-cycled" many times
between the time that it leaves the surface of the Atlantic Ocean
and is carried by the prevailing westerly winds into the Amazon
basin, to the time that it is carried back to the ocean by the Amazon
River.
A long
and winding river road. The total length
of the Amazon River from its source springs in the Andes (taking
the Ucayali River as the continuation of the main river into the
Andes), is estimated at 6518 km (not including all river bends,
and measured the short distance around Marajó Island in the
mouth of the Amazon), or ~4075 miles in length. This is exceeded
only by the Nile River (including the Kagera River) of Africa with
a total length of 6671 km (4170 miles). The headwaters are located
high in the Andes at an elevation of about 5,200 meters (17,000
feet), and only 190 kilometers (120 miles) from the Pacific Ocean.
Like
mothers, like daughters.... Two
of the tributaries of the Amazon, the Juruá and the Madeira
Rivers, are both over 3,300 km (2,060 miles) long. About 1,100 other
tributaries empty into the Amazon River.
Talk
about a big mouth!! The mouth of the Amazon
is over 320 km wide (approximately 200 miles), and contains the
worlds largest freshwater island, Marajó Island, with an
area of 48,000 km2.
Momma
was not a Rolling Stone!
After leaving the Andes, the elevational gradient of the
Amazon is very low. At Iquitos, Peru, still some 3,600 km (2,250
miles) from the Atlantic, the river-level at low-water season is
only about 100 m (a bit more than 300') above sea-level, and the
slope is around 2 cm (less than one inch) vertical change per kilometer.
In the lower Amazon, at the mouth of Rio Negro and still 1,500 km
from the Atlantic, the river-level at low-water season is only 15
m (~47') above sea-level, and the slope is about 1 cm per kilometer.
NEWS
FLASH!! Rumpelstiltskin Drowns in
Slow Flood. The Amazon is not a good place to fall permanently
asleep on the river bank! Seasonal water levels can vary up to 20
meters (65 feet) in the middle Amazon region. Towards the mouth
of the Amazon, the yearly change becomes less and less, but even
near the mouth of the Amazon (at the Rio Xingu), it is still 4 meters
(12 feet).
Flooded
but not drowned. The seasonal variation in
water levels means that huge areas along the major rivers in the
Amazon basin are periodically flooded. The total area of flooded,
or varzea, forest is between 50-60,000 km2, or about 4% of the total
area of the Amazon rainforest. These flooded forest areas may extend
as much as 80 kilometers (50 miles) from the main river channels,
and the forest vegetation of the varzea is well adapted to being
seasonally flooded. The structure and species composition of the
varzea is very different from non-flooded upland (or terra firme)
forest areas. Varzea forest areas are critical to the freshwater
fisheries of the Amazon Basin.
Go with
the flow. Despite the low slope of the Amazon,
the river currents can be surprisingly strong. In the lower Amazon
(with the lowest slope), current speeds range from 0.5-1.0 meters
per second at low water, and twice that at flood stage. In localized
areas, current speeds can reach as high as 3 meters (9.8 feet) per
second.
Ships
on a submarine river?? The width of the Amazon
at Iquitos, Peru (3,600 km/2,250 miles from the ocean) is about
2 km. Ocean-going ships can easily access the Port of Iquitos at
high water, as the mean depth of the current-canal of the Amazon
is between 40 and 50 m (or up to 150+ feet deep), and in places,
over 100 m (over 300 feet) deep. Even hundreds of miles away from
the ocean, sections of the bottom of the river channel actually
lie below sea level!
World's
Biggest Outhouse! In the Atlantic Ocean beyond
the mouth of the Amazon, and resting on the continental shelf, the
Amazon sediment cone has a length of about 680 km and a width of
250 km. These fine grained deposits (mostly clay/mud particles)
on the ocean floor are over 11,000 meters (36,000 feet) thick. This
is mostly sediment that has been carried downriver from the Andes
Mountains, the Guianan Shield (to the North) and the Brazilian Shield
(to the south), by the river current, and which settled out of the
water column once the river current dissipated into the waters of
the Atlantic Ocean.
World's
Biggest Washtub. The Amazon basin (the watershed
of the Amazon River) is 7,050,000 km2 in area (or about 2,500,000
square miles), and covers about 40% of South America. Of this area,
approximately 5,000,000 km2 is (or was) covered by high tropical
rainforest, with the remainder covered by savannah ("campo")
or scrubby woodland ("cerrado"). The Amazon basin covers
significant portions of the countries of Brazil, Peru, Colombia,
Ecuador, Venezuela and Bolivia, though the major part of the watershed
lies within Brazil. The next largest tropical watershed, that of
the Congo River, at 3,690,000 km2, is only half the size of the
Amazon basin.
Violent
Revolution Rocks South America! Although
it now empties into the Atlantic Ocean, the Amazon once flowed into
the Pacific! The uplift of the Andes Mountains about 65 million
years ago in a geological event called the Laramide Revolution cut
the flow to the Pacific, and forced the Amazon River to flow eastward.
This revolution took place when the westward-moving South American
(geological or tectonic) plate crashed headlong into the eastern-moving
Nazca Plate. The Nazca plate was forced beneath the South American
plate, lifting up the Andes mountains in a process that continues
to this day, as evidenced by the many earthquakes and high volcanic
activity of the Andes region.
But It's
a Dry Heat... The Amazon
basin has not always been an area of lush tropical rainforest. At
several times during its history, the basin has been the location
of huge lakes and shallow seas. Salt deposits up to 600 meters thick
(nearly 2000 feet!) have also been found in some locations, indicating
that at one time, the basin may have been desert-like, drying up
the shallow seas and creating the salt deposits.
A Well
Watered Desert! Would you believe that the
Amazon River has its own sand dunes? Echogrammes of the river bed
below the mouth of the Rio Negro show giant sand dunes as long as
600 meters (2000 feet) and up to 12 meters (39 feet) in height.
These dunes are gradually moved downstream in the same manner that
wind moves sand-dunes in "true" deserts!
A Bouillabaisse
of Fishes. The Amazon basin is home to over
2,500 species of fish, more species than are found in the entire
Atlantic Ocean, and some experts estimate that there may be as many
as 5,000 species! These range from giant air-breathing fish (Arapaima
gigas) and river catfish weighing up to 600-700 lbs, to tiny
tetras, electric eels, sting-rays, needlefish, fresh-water flying-fish,
and knife-fish. The fish fauna of many river systems is poorly known,
and new species are discovered yearly, even in the "better-known"
areas!
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