Rivers are usually freshwater and natural flowing towards something; be it an ocean, sea, lake underground or into another river.
Size matters!
The smaller cousins to rivers are really streams, creeks, brooks or rivulets and most don’t call them rivers per say.
“Rivers and their tributaries are the veins of the planet, pumping freshwater to wetlands and lakes and out to sea. They flush nutrients through aquatic ecosystems, keeping thousands of species alive, and help sustain fisheries worth billions of dollars.
Rivers are also the lifeblood of human civilizations. They supply water to cities, farms, and factories. Rivers carve shipping routes around the globe, and provide us with food, recreation, and energy. Hydroelectric plants built from bank to bank harness the power of water and convert it to electricity.”
the discovery of Extraterrestrial rivers have recently been found off Planet Earth! There is now evidence that there were/are rivers on Titan (Titan is the largest moon of Saturn with a dense atmosphere, and clear evidence of surface liquid) and outflows on Mars. Scientists believe we will find planets and moons that have ‘habitable zones’ with flowing water!
- Youthful river: A river with a steep gradient that has very few tributaries and flows quickly. Its channels erode deeper rather than wide.
- Mature river: A river with a gradient that is less steep than those of youthful rivers and flows more slowly and erodes wider. A mature river is fed by many tributaries and has more discharge than a youthful river.
- Old river: A river with a low gradient and low erosive energy. Old rivers are characterized by flood plains, such as the Nile River.
- Rejuvenated river: A river with a gradient that is raised by the earth’s crust moving as in tectonic activity.
Amazon
Second longest river in the world, it spans 6,400 km (4,000 miles). It would be as if Canada had a river that went from Coast to Coast across it’s length! By volume, the Amazon is the largest river with a total river flow that in approximately 1/5 of the world’s total fresh water. It flows through 6 countries (Peru, Bolivia, Venezuela, Colombia, Ecuador, Brazil) and empties into the Atlantic. It has over 3,000 species of fish including the Amazon River Dolphin, a shark and don’t forget the famous sharp toothed piranha.
The Nile is the world’s longest river spanning 6,650 (4,132 miles) from the Mediterranean to into East Africa. There are 2 tributaries, the White Nile and the Blue Nile.
This is an example of a mature river, as the fertile silt deposits played a major role in the development of the Egyptian civilization.
The Yangtze River is the longest river in China and the 3rd longest in the world at 6300 km (3915). It starts from a glacier in the Tibetan plateau and passes through the gorgeous Yangtze Gorges finally flowing into the China Sea.
The Yangtze is one of the busiest waterways with commercial traffic and river cruises.
The Danube is the 2nd longest river in Europe after the Volga, but it’s one of the most important. It borders and crosses 10 different European countries and was the Roman Empire’s long standing Frontier. It starts in the Germany’s Black Forest and is 2850 km (1771 miles) long flowing into the Black Sea.
Boat Cruises along the Danube have become very popular in the last 5 years, as it passes through 4 major European Capital Cities.
The Ganges is not one of the longest rivers at 2,510 km (1,560 miles) but is considered by many as the holiest in Hinduism. It originates in the Western Himalayas in India and flows into the Bay of Bengal.
It is India’s National River, as Hindus scatter ashes of loved ones in the river and some believe life is incomplete without taking a bath in the Ganges at least once.
http://www.touropia.com/most-important-rivers-in-the-world/
https://en.wikipedia.org/wiki/River
http://environment.nationalgeographic.com/environment/freshwater/rivers/
https://en.wikipedia.org/wiki/Titan_(moon)