The Nile is a major north-flowing river in Africa, generally regarded as the longest river in the world.

The Nile has two major tributaries, the White Nile and Blue Nile, the latter being the source of most of the Nile's water and fertile soil, but the former being the longer of the two. The White Nile rises in the Great Lakes region of central Africa, with the most distant source in southern Rwanda and flows north from there through Tanzania, Lake Victoria, Uganda and southern Sudan, while the Blue Nile starts at Lake Tana in Ethiopia, flowing into Sudan from the southeast. The two rivers meet near the Sudanese capital of Khartoum.

The northern section of the river flows almost entirely through desert, from Sudan into Egypt, a country whose civilization has depended on the river since ancient times. Most of the population and cities of Egypt lie along those parts of the Nile valley north of Aswan, and nearly all the cultural and historical sites of Ancient Egypt are found along the banks of the river. The Nile ends in a large delta that empties into the Mediterranean Sea.

Tributaries and distributaries

The drainage basin of the Nile covers 3,254,555 square kilometres (1,256,591 sq mi), about 10% of the area of Africa.

There are two great tributaries of the Nile, joining at Khartoum: the White Nile, starting in equatorial East Africa, and the Blue Nile, beginning in Ethiopia. Both branches are on the western flanks of the East African Rift, the southern part of the Great Rift Valley. Below the Blue and White Nile confluence the only remaining major tributary is the Atbara River, which originates in Ethiopia north of Lake Tana, and is around 800 kilometres (500 mi) long. During the dry period of January to June, there is typically no flow from the Atbara River. It flows only while there is rain in Ethiopia and dries very rapidly. It joins the Nile approximately 300 kilometres (200 mi) north of Khartoum.

The Nile is unusual in that its last tributary (the Atbara) joins it roughly halfway to the sea. From that point north, the Nile diminishes because of evaporation.

The course of the Nile in Sudan is distinctive. It flows over six groups of cataracts, from the first at Aswan to the sixth at Sabaloka (just north of Khartoum) and then turns to flow southward for a good portion of its course, before again returning to flow north to the sea. This is called the "Great Bend of the Nile".

North of Cairo, the Nile splits into two branches (or distributaries) that feed the Mediterranean: the Rosetta Branch to the west and the Damietta to the east, forming the Nile Delta.

The Nile basin is complex, and because of this, the discharge at any given point along the mainstem depends on many factors including weather, diversions, evaporation and evapotranspiration, and groundwater flow.

White Nile

The source of the Nile is sometimes considered to be Lake Victoria, but the lake itself has feeder rivers of considerable size. The most distant stream—and thus the ultimate source of the Nile—emerges from Nyungwe Forest in Rwanda, via the Rukarara, Mwogo, Nyabarongo and Kagera rivers, before flowing into Lake Victoria in Tanzania near the town of Bukoba.

The Nile leaves Lake Victoria at Ripon Falls near Jinja, Uganda, as the Victoria Nile. It flows for approximately 500 kilometres (300 mi) farther, through Lake Kyoga, until it reaches Lake Albert. After leaving Lake Albert, the river is known as the Albert Nile. It then flows into Sudan, where it is known as the Bahr al Jabal ("River of the Mountain"). The Bahr al Ghazal, itself 716 kilometres (445 mi) long, joins the Bahr al Jabal at a small lagoon called Lake No, after which the Nile becomes known as the Bahr al Abyad, or the White Nile, from the whitish clay suspended in its waters. When the Nile flooded it left a rich silty deposit which fertilised the soil. The Nile no longer floods annually since the completion of the Aswan Dam in 1970. From Lake No, the river flows to Khartoum. An anabranch river, the Bahr el Zeraf, flows out of the Nile's Bahr al Jabal section and rejoins the White Nile.

The term "White Nile" is used in both a general sense, referring to the entire river above Khartoum, and in a limited sense, describing the section between Lake No and Khartoum.

The flow rate of the Albert Nile at Mongalla is almost constant throughout the year and averages 1,048 m3/s (37,000 cu ft/s). After Mongalla, the Nile is known as the Bahr El Jebel, which enters the enormous swamps of the Sudd region of Sudan. More than half of the Nile's water is lost in this swamp to evaporation and transpiration. The average flow rate in the Bahr El Jebel at the tails of the swamps is about 510 m3/s (18,000 cu ft/s). From here it soon meets with the Sobat River and forms the White Nile.

The Bahr al Ghazal and the Sobat River are the two most important tributaries of the White Nile in terms of drainage area and discharge. The Bahr al Ghazal's drainage basin is the largest of any of the Nile's sub-basins, measuring 520,000 square kilometres (200,000 sq mi) in size, but it contributes a relatively small amount of water, about 2 m3/s (71 cu ft/s) annually, due to tremendous volumes of water being lost in the Sudd wetlands. The Sobat River, which joins the Nile a short distance below Lake No, drains about half as much land, 225,000 km2 (86,900 sq mi), but contributes 412 cubic metres per second (14,500 cu ft/s) annually to the Nile. When in flood the Sobat carries a large amount of sediment, adding greatly to the White Nile's color.

The average flow of the White Nile at Malakal, just below the Sobat River, is 924 m3/s (32,600 cu ft/s); the peak flow is approximately 1,218 m3/s (43,000 cu ft/s) in early March and minimum flow is about 609 m3/s (21,500 cu ft/s) in late August. This fluctuation is due the substantial variation in the flow of the Sobat, which has a minimum flow of about 99 m3/s (3,500 cu ft/s) in August and a peak flow of over 680 m3/s (24,000 cu ft/s) in early March. During the dry season (January to June) the White Nile contributes between 70% and 90% of the total discharge from the Nile.

Blue Nile

The Blue Nile springs from Lake Tana in the Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres (870 mi) to Khartoum, where the Blue Nile and White Nile join to form the Nile. 90% of the water and 96% of the transported sediment carried by the Nile originates in Ethiopia, with 59% of the water from the Blue Nile (the rest being from the Tekezé, Atbarah, Sobat, and small tributaries). The erosion and transportation of silt only occurs during the Ethiopian rainy season in the summer, however, when rainfall is especially high on the Ethiopian Plateau; the rest of the year, the great rivers draining Ethiopia into the Nile (Sobat, Blue Nile, Tekezé, and Atbarah) have a weaker flow.

The Blue Nile contributes approximately 80-90% of the Nile River discharge. The flow of the Blue Nile varies considerably over its yearly cycle and is the main contribution to the large natural variation of the Nile flow. During the wet season the peak flow of the Blue Nile will often exceed 5,663 m3/s (200,000 cu ft/s) in late August (a difference of a factor of 50). During the dry season the natural discharge of the Blue Nile can be as low as 113 m3/s (4,000 cu ft/s), although upstream dams regulate the flow of the river.

Before the placement of dams on the river the yearly discharge varied by a factor of 15 at Aswan. Peak flows of over 8,212 m3/s (290,000 cu ft/s) would occur during late August and early September and minimum flows of about 552 m3/s (19,500 cu ft/s) would occur during late April and early May.

Yellow Nile

The Yellow Nile is a former tributary that connected the Ouaddaï Highlands of eastern Chad to the Nile River Valley ca. 8000 to ca. 1000 BCE. Its remains are known as the Wadi Howar. The wadi passes through Gharb Darfur near the northern border with Chad and meets up with the Nile near the southern point of the Great Bend.

Lost headwaters

Formerly Lake Tanganyika drained northwards along the African Rift Valley into the Albert Nile, making the Nile about 900 miles (1,400 km) longer, until blocked in Miocene times by the bulk of the Virunga Volcanoes.

History

The Nile (iteru in Ancient Egyptian) has been the lifeline of civilization in Egypt since the Stone Age, with most of the population and all of the cities of Egypt resting along those parts of the Nile valley lying north of Aswan. Climate change at the end of the most recent ice age led to the formation the Sahara desert, possibly as long ago as 3400 BC.

credited to wikipedia

The Amazon River of South America is the largest river in the world with a total river flow greater than the next ten largest rivers combined. The Amazon, which has the largest drainage basin in the world, accounts for approximately one-fifth of the world's total river flow.

In its upper stretches the Amazon river is called Apurímac (in Peru) and Solimões (in Brazil).

During the wet season, parts of the Amazon exceed 190 kilometres (120 mi) in width. Because of its vast dimensions, it is sometimes called The River Sea. At no point is the Amazon crossed by bridges. This is not because of its huge dimensions; in fact, for most of its length, the Amazon's width is well within the capability of modern engineers to bridge. However, the bulk of the river flows through tropical rainforest, where there are few roads and even fewer cities, so there is no need for crossings.

While the Amazon is the largest river in the world by most measures, the current consensus within the geographic community holds that the Amazon is the second longest river, just slightly shorter than the Nile.

Drainage area

The Amazon Basin, the largest drainage basin in the world, covers about 40 percent of South America, an area of approximately 7,050,000 square kilometres (2,720,000 sq mi). It gathers its waters from 5 degrees north latitude to 20 degrees south latitude. Its most remote sources are found on the inter-Andean plateau, just a short distance from the Pacific Ocean.

The Amazon River and its tributaries more than triples over the course of a year. In an average dry season, 110,000 square kilometres (42,000 sq mi) of land are water-covered, while in the wet season, the flooded area of the Amazon Basin rises to 350,000 square kilometres (140,000 sq mi).

The quantity of water released by the Amazon to the Atlantic Ocean is enormous: up to 300,000 cubic metres (11,000,000 cu ft) per second in the rainy season, with an average of 209 000 m³/s from 1973 to 1990. The Amazon is responsible for about 20% of the total volume of freshwater entering the ocean. Potable water can be drawn from the ocean while still out of sight of the coastline, and the salinity of the ocean is notably lower 500 kilometres (310 mi) out to sea.

There is a natural water union between the Amazon and the Orinoco basins, the so-called Casiquiare canal. Actually the Casiquiare is a river distributary of the upper Orinoco, which flows southward into the Rio Negro, which in turn flows into the Amazon. The Casiquiare is the largest river on the planet that links two major river systems, a so-called bifurcation.

Origins

The Amazon river has a series of major river systems in Peru and Ecuador, some of which flow into the Marañón and Ucayali, others directly into the Amazon proper. Among others, these include the following rivers: Morona, Pastaza, Nucuray, Urituyacu, Chambira, Tigre, Nanay, Napo, and Huallaga.

The most distant source of the Amazon was firmly established in 1996, 2001, and 2007 as a glacial stream on a snowcapped 5,597 m (18,363 ft) peak called Nevado Mismi in the Peruvian Andes, roughly 160 km (99 mi) west of Lake Titicaca and 700 km (430 mi) southeast of Lima. The waters from Nevado Mismi flow into the Quebradas Carhuasanta and Apacheta, which flow into the Río Apurímac which is a tributary of the Ucayali which later joins the Marañón to form the Amazon proper. (While this is the point at which most geographers place the beginning of the Amazon proper, in Brazil the river is known at this point as the Solimões das Águas.) Soon thereafter the darkly colored waters of the Rio Negro meet the sandy colored Rio Solimões, and for over 6 km (4 mi) these waters run side by side without mixing.

After the confluence of Río Apurímac and Ucayali, the river leaves Andean terrain and is instead surrounded by floodplain. From this point to`the Marañón, some 1,600 km (990 mi) , the forested banks are just out of water, and are inundated long before the river attains its maximum flood-line. The low river banks are interrupted by only a few hills, and the river enters the enormous Amazon Rainforest.

The river systems and flood plains in Brazil, Peru, Ecuador, Colombia and Venezuela whose waters drain into the Solimões and its tributaries are called the "Upper Amazon". The Amazon River proper runs mostly through Brazil and Peru, and it has tributaries reaching into Venezuela, Colombia, Ecuador, and Bolivia.

Flooding

Not all of the Amazon's tributaries flood at the same time of the year. Many branches begin flooding in November, and may continue to rise until June. The rise of the Rio Negro starts in February or March, and it also begins to recede in June. The Madeira rises and falls two months earlier than most of the rest of the Amazon.

The average depth of the river in the height of the rainy season is 40 metres (130 ft) and the average width can be nearly 40 km (25 mi).

The main river (which is between approximately one and six miles (10 km) wide) is navigable for large ocean steamers to Manaus, 1,500 kilometres (930 mi) upriver from the mouth. Smaller ocean vessels of 3,000 tons or 9,000 tons and 5.5 metres (18 ft) draft can reach as far as Iquitos, Peru, 3,600 kilometres (2,200 mi) from the sea. Smaller riverboats can reach 780 kilometres (480 mi) higher as far as Achual Point. Beyond that, small boats frequently ascend to the Pongo de Manseriche, just above Achual Point.

Geography

At some points, for long distances, the river divides into two main streams with inland and lateral channels, all connected by a complicated system of natural canals, cutting the low, flat igapó lands, which are never more than 5 metres (16 ft) above low river, into many islands.

From the town of Canaria at the great bend of the Amazon to the Negro, only very low land is found, resembling that at the mouth of the river. Vast areas of land in this region are submerged at high water, above which only the upper part of the trees of the sombre forests appear. Near the mouth of the Rio Negro to Serpa, nearly opposite the river Madeira, the banks of the Amazon are low, until approaching Manaus, they rise to become rolling hills. At Óbidos, a bluff 17 m (56 ft) above the river is backed by low hills. The lower Amazon seems to have once been a gulf of the Atlantic Ocean, the waters of which washed the cliffs near Óbidos.

Only about 10% of the water discharged by the Amazon enters the mighty stream downstream of Óbidos, very little of which is from the northern slope of the valley. The drainage area of the Amazon Basin above Óbidos city is about 5 million square kilometres (2,000,000 sq mi), and, below, only about 1 million square kilometres (400,000 sq mi or around 20%), exclusive of the 1.4 million square kilometres (540,000 sq mi) of the Tocantins basin.

In the lower reaches of the river, the north bank consists of a series of steep, table-topped hills extending for about 240 kilometres (150 mi) from opposite the mouth of the Xingu as far as Monte Alegre. These hills are cut down to a kind of terrace which lies between them and the river.

On the south bank, above the Xingu, an almost-unbroken line of low bluffs bordering the flood-plain extends nearly to Santarém, in a series of gentle curves before they bend to the south-west, and, abutting upon the lower Tapajós, merge into the bluffs which form the terrace margin of the Tapajós river valley.

Mouth

The definition of what exactly and how wide is the mouth of the Amazon is a matter of dispute, because of the area's peculiar geography. Most particularly, sometimes the Pará River is included, whereas sometimes it is just considered the independent lower reach of the Tocantins River. The Pará river estuary alone is 60 km (37 mi) wide. The Pará and the Amazon are connected by a series of river channels called furos near the town of Breves; between them lies Marajó, an island almost the size of Switzerland that is the world's largest combined river/sea island.

If the Pará river and the Marajó island ocean frontage are included, the Amazon estuary is some 330 kilometres (210 mi) wide. In this case, the width of the mouth of the river is usually measured from Cabo Norte, in the Brazilian state of Amapá, to Ponta da Tijoca near the town of Curuçá, in the state of Pará. By this criterion, the Amazon is wider at its mouth than the entire length of the River Thames in England.

A more conservative measurement excluding the Pará river estuary, from the mouth of the Araguari River to Ponta do Navio on the northern coast of Marajó, would still give the mouth of the Amazon a width of over 180 kilometres (110 mi). If only the river's main channel is considered, between the islands of Curuá (state of Amapá) and Jurupari (state of Pará), the width falls to just about 15 kilometres (9.3 mi) - but that is still impressive for any river. It also has a 13% dumpage rate into the basin.

Tidal bore (pororoca)

The tension between the river's strong push and the Atlantic tides causes a phenomenon called a tidal bore, a powerful tidal wave that flows rapidly inland from the sea up the Amazon mouth and nearby coastal rivers several times a year at high tide. Tidal bores also occur in other river mouths around the world, but the Amazon's are among the world's highest and fastest, probably second only to those of Qiantang River in China. In the Amazon, the phenomenon is locally known as the pororoca.

The pororoca occurs especially where depths do not exceed 7 metres (23 ft). It starts with a very loud roar, constantly increasing, and advances at the rate of 15–25 km/h (9–16 mph), with a breaking wall of water 1.5–4.0-metres (5–13 ft) high that may travel violently several kilometres up the Amazon and other rivers close to its mouth. It is particularly intense in the rivers of the coast of the state of Amapá north of the mouth of the Amazon, such as the Araguari River, but can be observed in Pará rivers as well.

The bore is the reason the Amazon does not have a protruding delta; the ocean rapidly carries away the vast volume of silt carried by the Amazon, making it impossible for a delta to grow past the shoreline. The region also has very high tides, sometimes reaching 6 metres (20 ft) and has become a popular spot for river surfing.

Wildlife

More than one-third of all species in the world live in the Amazon Rainforest, a giant tropical forest and river basin with an area that stretches more than 5.4 million square kilometres (2.1 million sq mi), and is the richest tropical forest in the world. The Amazon River has over 3,000 recognized species of fish and that number is still growing.

Along with the Orinoco, the river is one of the main habitats of the boto, also known as the Amazon River Dolphin (Inia geoffrensis). It is the largest species of river dolphin, and it can grow to lengths of up to 2.6 metres (8.5 ft). The boto is the subject of a very famous legend in Brazil about a dolphin that turns into a man and seduces maidens by the riverside. The tucuxi (Sotalia fluviatilis), also a dolphin species, is found both in the rivers of the Amazon Basin and in the coastal waters of South America.

The Amazonian Manatee is another conspicuous mammal living in the waters of the Amazonian basin.

Also present in large numbers is the notorious piranha, a carnivorous fish which congregates in large schools, and may attack livestock and even humans. However, only a few of its species are known to attack humans, most notably Pygocentrus nattereri, the Red-bellied Piranha.

The bull shark (Carcharhinus leucas) has been reported 4,000 kilometres (2,500 mi) up the Amazon River at Iquitos in Peru. The arapaima, known in Brazil as the pirarucu (Arapaima gigas), is a South American tropical freshwater fish. It is one of the largest freshwater fish in the world, reportedly with a maximum length in excess of 4.5 metres (15 ft) and weight up to 200 kilograms (440 lb). Another Amazonian freshwater fish is the arowana (or aruanã in Portuguese), such as the Silver arowana (Osteoglossum bicirrhosum), which is also a predator and very similar to the arapaima, but only reaches a length of maximum 120 centimetres (47 in). The candirú are a number of genera of parasitic, freshwater catfish in the family Trichomycteridae; all are native to the Amazon River. They sometimes attack humans and have been known to enter the urethras of bathers. The electric eel (Electrophorus electricus) is also found in the river.

The anaconda snake is found in shallow waters in the Amazon Basin. One of the world's largest species of snake, the anaconda spends most of its time in the water, with just its nostrils above the surface. In addition to the thousands of species of fish, the river supports crabs, algae, and turtles.

credited to wikipedia and flickr: balsa

The Yangtze River, or Chang Jiang, is the longest river in China and Asia, and the third-longest in the world. The river is about 6,300 kilometres (3,915 mi) and flows from its source in Qinghai Province, eastwards into the East China Sea at Shanghai. It acts as a dividing line between North and South China, although geographers generally consider the Qinling-Huai River line to be the official line of geographical division. As the largest river in the region, the Yangtze is historically, culturally, and economically important to China. One of the dams on the river, the Three Gorges Dam, is the largest hydro-electric power station in the world. The section of the river flowing through deep gorges in Yunnan province is part of the Three Parallel Rivers of Yunnan Protected Areas: a UNESCO World Heritage Site.

The name Yangtze River, as well as other similar names such as Yangtse River, Yangzi River and Yangtze Kiang, is derived from Yangzi Jiang listen. The name supposedly comes from the ancient ferry crossing Yangzi Jin. Because it was the name first heard by missionaries and traders, this name was applied in English to the whole river. The modern Chinese name, Chang Jiang, literally means "Long River". (Jiang is the classical Chinese for river.) and may sometimes also be used in English. It is also known to many as the 'Main Street' of China.

Like many rivers, the river is known by different names over its course. At its source, it is called in Chinese the Dangqu. Downstream, it is called the Tuotuo River and then the Tongtian River. Where it runs through deep gorges parallel to the Mekong and the Salween before emerging onto the plains of Sichuan, it is known as the Jinsha River. The Three Gorges Dam on the river is the largest dam in the world.

The Yangtze was earlier known to the Chinese as simply Jiang, which has become a generic name meaning "river", or the Da Jiang. The Tibetan name for the river is Drichu. The Yangtze is sometimes referred to as the Golden Waterway.

Geography

The river originates in a glacier lying on the west of Geladandong Mountain in the Dangla Mountain Range on the eastern part of the Tibetan plateau. It runs eastward through Qinghai, turning southward down a deep valley at the border of Sichuan and Tibet to reach Yunnan. In the course of this valley, the river's elevation drops from above 5000 m to less than 1000 m. The headwaters of the Yangtze are situated at an elevation of about 4,900 m (16,100 ft). In its descent to sea level, the river falls to an altitude of 305 m (1,001 ft) at Yibin, Sichuan Province, the head of navigation for riverboats, and to 192 m (630 ft) at Chongqing. Between Chongqing and Yichang (I-ch'ang), at an altitude of 40 m (130 ft) and a distance of about 320 km (200 mi), it passes through the spectacular Yangtze Gorges, which are noted for their natural beauty but are dangerous to shipping.

It enters the basin of Sichuan at Yibin. While in the Sichuan basin, it receives several mighty tributaries, increasing its water volume significantly. It then cuts through Mount Wushan bordering Chongqing and Hubei to create the famous Three Gorges. Eastward of the Three Gorges, Yichang is the first city on the Yangtze Plain.

After entering Hubei, the Yangtze receives more water from thousands of lakes. The largest of these lakes is Dongting Lake, which is located on the border of Hunan and Hubei provinces, and is the outlet for most of the rivers in Hunan. At Wuhan, it receives its biggest tributary, the Han River, bringing water from its northern basin as far as Shaanxi.

At the northern tip of Jiangxi, Lake Poyang, the biggest freshwater lake in China, merges into the river. The river then runs through Anhui and Jiangsu provinces, receiving more water from innumerable smaller lakes and rivers, and finally reaches the East China Sea at Shanghai.

Four of China's five main freshwater lakes contribute their waters to the Yangtze River. Traditionally, the upstream part of the Yangtze River refers to the section from Yibin to Yichang; the middle part refers to the section from Yichang to Hukou County, where Lake Poyang meets the river; the downstream part is from Hukou to Shanghai. It is home to many thousands of people.

Characteristics

The Yangtze flows into the East China Sea and was navigable by ocean-going vessels up a thousand miles from its mouth even before the Three Gorges Dam was built. As of June 2003, this dam spans the river, flooding Fengjie, the first of a number of towns affected by the massive flood control and power generation project. This is the largest comprehensive irrigation project in the world and has a significant impact on China's agriculture. Its proponents argue that it will free people living along the river from floods that have repeatedly threatened them in the past and will offer them electricity and water transport—though at the expense of permanently flooding many existing towns (including numerous ancient cultural relics) and causing large-scale changes in the local ecology.

Opponents of the dam point out that there are three different kinds of floods on the Yangtze River: floods which originate in the upper reaches, floods which originate in the lower reaches, and floods along the entire length of the river. They argue that the Three Gorges dam will actually make flooding in the upper reaches worse and have little or no impact on floods which originate in the lower reaches. Twelve hundred years of low water marks on the river were recorded in the inscriptions and the carvings of carp at Baiheliang, now submerged.

The Yangtze is flanked with metallurgical, power, chemical, auto, building materials and machinery industrial belts and high-tech development zones. It is playing an increasingly crucial role in the river valley's economic growth and has become a vital link for international shipping to the inland provinces. The river is a major transportation artery for China, connecting the interior with the coast.

The river is one of the world's busiest waterways. Traffic includes commercial traffic transporting bulk goods such as coal as well as manufactured goods and passengers. Cargo transportation reached 795 million tons in 2005. River cruises several days long, especially through the beautiful and scenic Three Gorges area, are becoming popular as the tourism industry grows in China.

Flooding along the river has been a major problem. The rainy season in China is May and June in areas south of Yangtze River, and July and August in areas north of it. The huge river system receives water from both southern and northern flanks, which causes its flood season to extend from May to August. Meanwhile, the relatively dense population and rich cities along the river make the floods more deadly and costly. The most recent major floods were the 1998 Yangtze River Floods, but more disastrous were the 1954 Yangtze River Floods, killing around 30,000 people. Other severe floods included those of 1911, which killed around 100,000, 1931 (145,000 dead), and 1935 (142,000 dead).

The Yangtze is very polluted, especially in Hubei (Shashi District).

History

The Yangtze River is important to the cultural origins of southern China. Human activity was found in the Three Gorges area as far back as 27 thousand years ago, initiating debate over the origin of the Chinese people. In the Spring and Autumn Period, Ba and Shu were located along the western part of the river, covering modern Sichuan, Chongqing, and western Hubei; Chu was located along the central part of river, corresponding to Hubei, Hunan, Jiangxi, and southern Anhui. Wu and Yue were located along the eastern part of the river, now Jiangsu, Zhejiang, and Shanghai. Although the Yellow River region was richer and more developed at that time, the milder climate and more peaceful environment made the Yangtze River area more suitable for agriculture.

From the Han Dynasty, the region of the Yangtze River became more and more important to China's economy. The establishment of irrigation systems (the most famous one is Dujiangyan, northwest of Chengdu, built during the Warring States period) made agriculture very stable and productive. By the Song dynasty, the area along the Yangtze had become among the most wealthiest and developed parts of the country, especially in the lower reaches of the river. Early in the Qing dynasty, the region called Jiangnan (that includes the southern part of Jiangsu, the northern part of Zhejiang, and the southeastern part of Anhui) provided 1/3-1/2 of the nation's revenues.

The Yangtze has long been the backbone of China's inland water transportation system, which remained particularly important for almost two thousand years, until the construction of the national railway network during the 20th century. The Grand Canal connects the lower Yangtze with the major cities of the Jiangnan region south of the river (Wuxi, Suzhou, Hangzhou) and with northern China (all the way to Beijing). The less well known ancient Lingqu Canal, connecting the upper Xiang River with the headwaters of the Guijiang, allowed a direct water connection from the Yangtze Basin to the Pearl River Delta.

Historically, the Yangtze became the political boundary between north China and south China several times (see History of China) because of the difficulty of crossing the river. This occurred notably during the Southern and Northern Dynasties, and the Southern Song. Many battles took place along the river, the most famous being the Battle of Red Cliffs in 208 AD during the Three Kingdoms period.

Politically, Nanjing was the capital of China several times, although most of the time its territory only covered the southeastern part of China, such as the Wu kingdom in the Three Kingdoms period, the Eastern Jin Dynasty, and during the Southern and Northern Dynasties and Five Dynasties and Ten Kingdoms periods. Only the Ming occupied most parts of China from their capital at Nanjing, though it later moved the capital to Beijing. The ROC capital was located in Nanjing in the periods 1911-1912, 1927-1937, and 1945-1949.

credited to wikipedia

The Congo River is the largest river in western Central Africa and the most powerful on the continent. Its overall length of 2,900 miles (4,667 kilometers) makes it the second-longest in Africa (after the Nile). It is the fifth-longest river in the world, draining a basin of nearly 1.5 million square miles. The river also has the second-largest flow in the world, with a discharge of 1.5 million cubic feet of water per second, trailing only the Amazon, and the second-largest watershed of any river, again trailing the Amazon; its watershed is slightly larger than that of the Mississippi River.

The river and its tributaries flow through the second-largest rainforest in the world, the Congo Rainforest, second only to the Amazon Rainforest in South America. The dense rain forest, heavy rainfall, and poor soil of the basin that is traversed by the Congo results in sparse population, except for small settlements of hunters, farmers, and fishermen along or near the river. Since it is close to the equator, the climate is hot and humid.

Joseph Conrad termed the river and surrounding rainforest "the heart of darkness" after serving as a captain aboard a Congo steamer in the days of Leopold's reign. The area has long had the reputation as the mysterious land of pygmies, mythical beasts, dreadful plagues, and cannibals. A place of incredible beauty and power, it is also a place with a violent and sorrowful history.

Etymology

The Congo River is named after the ancient Kingdom of Kongo, which inhabited the lands at the mouth of the river at the time of European discovery. The Democratic Republic of Congo and Republic of Congo, both countries lying along the river's banks, are named after it. Between 1971 and 1997 the government of then-Zaire referred to it as the “Zaire River.”

History

Before continental drift opened the South Atlantic Ocean, the Congo was the upper part of a river roughly 7,500 miles (12,000 kilometers) long that flowed west across the parts of Gondwanaland that are now Africa and South America. Except for the beginning and end of its course, the river is uniformly elevated.

Bantu-speaking people have lived along the Congo for at least two thousand years, supporting themselves with fish from the river and farms on the fertile lands between the river and forest. A powerful kingdom of the Kongo people, centered at the mouth of the river, emerged by the 1300s.

Exploration

The Portuguese explorer Diogo Cão entered the Congo estuary on a voyage from 1482 to 1484 and claimed the area for his king. Those who tried to sail upriver encountered a narrow gorge that compressed the water into a powerful opposing current. In the river's final 220 miles from the edge of the central plateau to the coast, the Congo River drops more than a thousand feet and has 32 rapids. Difficult terrain made exploration on foot also treacherous. Following Cam, more than three hundred years elapsed before serious exploration of the Congo was undertaken.

Francisco José de Lacerda, a Portuguese explorer, reached the copper-rich Katanga region from the east in 1798, as did Arab traders in the first half of the 1800s. The Arabs extended their influence over the eastern Congo River Basin, engaging in the slave and ivory trades. In 1816 a British expedition went as far as Isangila. Scottish explorer and missionary David Livingstone visited the Luapula and Lualaba rivers in 1871, believing them to be sources of the Nile.

Henry Morton Stanley was the first European to navigate the river's length and report that the Lualaba was not a source of the Nile, as had been suggested. He returned on behalf of King Leopold of Belgium in 1876 and claimed huge swaths of land in the Conger River basin for the king, an area more than 76 times the size of Belgium. By 1885 Leopold ruled this huge area as his personal domain through his private army, the Force Publique. His legacy is one of exploitation and human rights abuses such as slavery and mutilation of the peoples. He was eventually forced to cede this land to Belgium in 1908.

Several other European explorers traveled up the Congo's tributaries in the 1880s, mapping out ten thousand miles of navigable waterways that were linked together.

Though trade in goods was the initial impetus for the Europeans, they quickly discovered that the slave trade was much more lucrative, and the river was the means to deliver them to the coast from inland areas once the supply of slaves dwindled on the coast. As the wealth from the slave trade filtered inland, the demand for slaves grew, leading to raids by some groups and migrations by others to escape the slavers. But the increased trade and multiplication of towns along the river had the unforeseen benefit of lifestyles becoming more similar and new crops and technologies being shared.

Source

The sources of the Congo River are in the highlands and mountains of the Great Rift Valley, as well as Lake Tanganyika and Lake Mweru, which feed the Lualaba River, becoming the Congo below Boyoma Falls. The Chambeshi River in Zambia is generally taken as the source of the Congo, in line with the accepted practice worldwide of using the longest tributary, as with the Nile River.

Course

The Congo River begins peacefully in the savannas just south of Lake Tanganyika. It gradually widens and picks up speed until it enters a 75-mile long canyon of rapids often referred to as the "Gates of Hell." Emerging from there, it enters the tropical rainforest area known as the Lualaba (or Upper Congo). Its course through the rainforest causes it to cross the equator twice.

Because the watershed of the Congo drains from both the Northern and Southern Hemisphere, it does not have the great seasonal fluctuations in water level as other great rivers. Its flow is relatively stable because part of its watershed is always in the zone of rain. The Upper Congo abruptly ends with Stanley Falls, a 60-mile stretch of rapids.

Stanley Falls gives way to the Middle Congo, a thousand-mile stretch of navigable river, nine miles wide in some areas. Along this quiet stretch of river is the city of Kisangani in the Democratic Republic of Congo. Kisangani is located where the Lualaba River becomes the Congo River north of the Boyoma Falls, and was the site of the first settlement of Henry Morton Stanley. The Congo flows generally west from Kisangani just below the falls, then gradually bends southwest, passing by Mbandaka, joining with the Ubangi River, and running into the Malebo Pool (Stanley Pool), a fifty-mile lake. Here the river slows to a virtual stand-still for 20 miles. At this point it is 15 miles wide and is and flanked by the capital cities of Kinshasa and Brazzaville.

Kinshasa and Brazzaville are on opposite sides of the river at the Pool, then the river narrows and falls through a number of cataracts in deep canyons (collectively known as the Livingstone Falls), running by Matadi and Boma, and into the sea at the small town of Muanda.

The river then flows into Livingstone Falls, a series of rapids and cataracts 220 miles long. There are some 32 cataracts, having as much power as all rivers and falls in the United States combined. The final one hundred miles to the Atlantic Ocean from the end of the falls is fully navigable.

The Congo and its tributaries drain parts of Central African Republic, Cameroon, Angola, Zambia, Democratic Republic of the Congo, Republic of the Congo, Equatorial Guinea and Gabon.

Ecology

Due to its size and other key elements, the Congo River and its basin are crucial to the ecological balance of the entire African continent. The river's basin encompasses the world's second-largest contiguous rainforest, surpassed only by that of the Amazon. The region is biologically diverse and a huge watershed.

The northern and southern parts of the basin are characterized by open grasslands and scattered trees. Wildlife is abundant along the river, which itself harbors more than two hundred species of fish.

According to the Water Resources Atlas, the Congo Basin Area encompasses 3,730,881 square miles. The entire Congo Watershed contains:

* Number of Fish Species: 700

* Number of Fish Endemics: 500

* Number of Amphibian Species: 227

* Number of Ramsar Sites: 4

* Number of Wetland-Dependent IBAs: 21

* Number of Endemic Bird Areas: 6

* Percent Protected Area: 4.7

Although the Congo water discharge levels were unstable throughout the second half of the twentieth century, the hydrologic balance of the river has provided some relief from the drought that has afflicted the river basin.

In 1999, the World Commission on Water for the Twenty-First Century found that the Congo was one of the world's cleanest rivers, in part due to the lack of industrial development along its shores until that time.

However, the situation is changing. Major threats to the large tropical rainforests and savannas are occurring due to increasing population and its demands. Uncontrolled hunting and fishing, illegal logging and the poaching of large mammals, deforestation, unplanned urban expansion and unrestrained extraction of oil and minerals are some of the major economic and environmental issues confronting the region.

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