The Nile is the longest river in the world, located in the northeast of Africa, and it is an international river. Originated in the highlands of Burundi in East Africa south of the equator, the mainstream flows through Burundi, Rwanda, Tanzania, Uganda, Sudan and Egypt, and finally flows into the Mediterranean Sea. The tributaries also flow through Kenya, Ethiopia, parts of the Democratic Republic of the Congo, Eritrea and other countries. With a total length of 6,670 kilometers, the main stream is the longest river in the world from the source of the Kagala River to the estuary. The basin covers an area of about 2.87 million square kilometers, accounting for more than one ninth of the African continent. The average annual runoff of the estuary is 8 1 100 million m3. The word "Nile" first appeared more than 2000 years ago. There are two theories about its origin: one comes from the Latin "Nile", which means "impossible". Because the middle and lower reaches of the Nile have been inhabited for a long time, but because of the barrier of waterfalls, people in the middle and lower reaches think that they can't understand the source of this river, so they named it the Nile. The second is that the word "nilus" evolved from the name of the ancient Egyptian Pharaoh (king) Nyroos. The Nile is formed by the confluence of three rivers: kagera river, White Nile and Blue Nile. The valley delta in the lower Nile is one of the earliest cradles of human civilization, where ancient Egypt was born. Up to now, 96% of Egypt's population and most of its agricultural production are concentrated here. Therefore, the Nile is regarded as the lifeline of Egypt. For thousands of years, the Nile River has flooded regularly from June to 10 every year. When the river reached its highest level in August, it flooded large fields on both sides of the river bank, and then people moved to high places to stay temporarily. After 10, the flood subsided, bringing fertile soil to the Nile. On these fertile land, people planted cotton, wheat, rice and jujube crops. A "green corridor" has been formed in the arid desert area. Egypt, an ancient civilization with a history of 5,000 years, has created splendid Egyptian culture here. Today, more than 90% of Egypt's population is distributed in the plains and deltas along the Nile. Egyptians call the Nile the mother of their lives. The upper reaches of the Mueller River in Soltani are 1730km long, which are called kagera river, Victoria Nile and Albert Nile respectively from top to bottom. From Nimulai to Khartoum, the middle reaches of the Nile River are 65,438+930 km long, which is called the White Nile, among which Malakal is also called the Jebel River, and the largest tributary, the Blue Nile (B65,438+0 UC Nile), flows into the lower reaches of Khartoum. The White Nile meets the Blue Nile, which is called the Nile and belongs to the lower reaches, with a length of about 3000km. The Nile River crosses the Sahara desert and enters the estuary delta north of Cairo, where it divides into two tributaries and flows into the Mediterranean Sea. The Nile, the mother of Egypt, originated in the plateau of eastern Africa south of the equator, winding and flowing from south to north. The Nile runs through northeast Africa, flows through Tanzania, Rwanda, Burundi, Uganda, Ethiopia, Sudan and Egypt, and finally flows into the Mediterranean Sea. With a total length of 6,740 kilometers, it is the largest river in Africa and the second longest river in the world, with a drainage area of 2.8 million square kilometers, equivalent to110 of the African continent. There are two sources of the Nile, one of which originated in the mountainous area of tropical Central Africa at 262 1 m, and is called the White Nile. The White Nile flows through huge lakes such as Lake Victoria and Lake Keoga, passes through the jungles of Uganda, and goes north via Sudan. Another source of the Nile is the Ethiopian plateau at an altitude of 2000 meters. It's called the Blue Nile. The Blue Nile is 680 kilometers long. It passes through Lake Tana, and then turns sharply, forming a current. This is the second largest waterfall in Africa-Tissett Falls. The roaring Blue Nile rushes into the Sudan Plain and meets the calm White Nile, which is the Nile we are familiar with. As early as more than 6000 years ago, the ancestors of the Egyptians thrived on both sides of the Nile. There is an Egyptian proverb, such as "Egypt is the Nile, and the Nile is the mother of Egypt". The Nile is indeed the source of life for the Egyptian people. It accumulated a lot of wealth for the coastal people and created the ancient Egyptian civilization. There are more than 70 pyramids, large and small, along the Nile River, just like a voluminous "history book", which contains the mystery of human civilization. More than 6,700 kilometers of the Nile created pyramids, created ancient Egypt, and created a miracle of mankind. The Nile runs through the northeast of the African continent, flows through Burundi, Rwanda, Tanzania, Uganda, Ethiopia, Sudan and Egypt, crosses the largest Sahara desert in the world, and finally empties into the Mediterranean Sea. The basin covers an area of about 3.35 million square kilometers, accounting for one ninth of the African continent, with a total length of 6,650 kilometers and an average annual flow of 3 100 cubic meters per second, making it the longest river in the world. Nile-Arabic means "big river". "Nile, Nile, longer than Tianhe" is a proverb that Sudanese people praise the Nile. There is a long section of the Nile flowing through the desert, where the river water is only lost and not replenished. Because the upstream source of the river is a tropical and rainy area, where the flow is huge, although a large amount of runoff is lost along the desert due to evaporation and leakage, the Nile can still maintain a long-flowing river. A river like the Nile, which is not formed by local runoff but simply flows through, is called a guest river. The local climatic conditions have no positive influence on the formation of these "guest rivers", only negative influence. Near the intersection of latitude and longitude on the left is Cairo. The lowest Nile divides into many tributaries, which flow into the Mediterranean, and all tributaries flow on the delta plain. The delta covers an area of about 24,000 square kilometers with flat terrain and criss-crossing rivers and canals. It is the cradle of ancient Egyptian culture and the political, economic and cultural center of modern Egypt. The upper reaches of the Nile River are kagera river, which originates from Burundi in the East African Plateau and flows into Lake Victoria in the lower reaches. The lake flows into Lake Keoha through Owen Falls, which is called Victoria Nile after leaving the lake, and then flows into Lake Abbott through Kabarega Falls. The lake flows from the northern end and is called Abbott Nile. Since Nimule, it has been named White Nile. The White Nile flows northward along the slope of the East African Plateau. The valley is deep and narrow with many steep beaches and waterfalls. From Bor to the north, the White Nile flows into the shallow swamp basin, with slow flow, and a large number of aquatic plants mainly papyrus grow in the river. After flowing out of the basin, the White Nile flows northward, and successively joins the Sobat River, the Blue Nile River and the atbara river, with no tributaries below. The banks of the White Nile are flat, with bedrock occasionally exposed. The intersection of the White Nile and the Blue Nile is surrounded by the Gizla Plain. The river below the confluence is called the Nile. The Nile flows through the sedimentary rock area north of Khartoum. This valley is a shallow canyon with a flat bottom. The valley near Wadi Halfa is only 20 1 m wide, so the valley from here to Aswan is very narrow. Below Aswan, the valley widens and extends to about 16km at Naja hammadi. The river is close to the east coast, and the valley plains are mostly in Hexi. There are six waterfalls between Kasimu and Aswan, which are all caused by the basement crystalline rocks that form the plateau on the east side of the valley and extend westward into the valley. The valley walls on both sides are asymmetrical, with the east wall high and steep and the west wall low and gentle. The White Nile originated in the rainy equatorial region, with abundant and stable water. However, after flowing out of the plateau into the basin, because the terrain is extremely flat and the water flow is extremely slow, the plants in the water also delay the progress of the water flow. In the dry areas at low latitudes, it evaporates strongly under the irradiation of sunlight, thus wasting a huge amount of water, and very little water can flow downstream. The annual average flow at the junction of the White Nile and the Blue Nile is 890 cubic meters per second, which is about half of that of the Blue Nile. The water in the lower Nile mainly comes from Sobat River, Blue Nile and atbara river, among which Blue Nile is the most important. Sobat River, a tributary of the White Nile, began to rise in May, and the highest water level appeared in June 5438+065438+ 10. At this time, the water level of Sobat River is higher than that of White Nile, which helps the latter to flow backward, thus enhancing the evaporation of water in the upper reaches of White Nile. The Blue Nile originates from Lake Tana in the Ethiopian Plateau, and its upper reaches are located in rainy areas in tropical mountainous areas, where it is rich in water resources. Due to the strong seasonal precipitation, the river flow changes greatly during the year. The amount of water in spring is limited, and it began to rise in June, and then rose rapidly and continuously, reaching a peak in early September. In the meantime, it will also make the White Nile flow backwards. The water level dropped from June 1 1 to February 1, followed by the dry season. The minimum flow in dry season is less than 100 cubic meter per second, which is about one sixtieth of the maximum flow in flood season. Atbara river also originated in the Ethiopian Plateau. Because it is located in the north, the rainfall is concentrated, and its drainage area is small, so the flow changes greatly. In winter, the river bed becomes a series of small lakes. The flood in the main stream of the Nile reached Khartoum in June and reached its highest level in September. The maximum flood peak appeared in Cairo in June+10, 5438. 60% of the total water of the Nile comes from the Blue Nile, 32% from the White Nile and 8% from atbara river. During the flood, Blue Nile accounted for 68%, atbara river accounted for 22%, and White Nile accounted for 10%. In dry season, the White Nile accounts for 83%, and the Blue Nile accounts for 17%. The Nile Valley is divided into seven regions: East African Lake Plateau, Mountain River Region, White Nile Region, Blue Nile Region, atbara river Region, Nile Region North of Khartoum and Nile Delta. 1862 On July 28th, British explorer John Henning speke discovered the "source" of the Nile in Lake Victoria. At that time, it was calculated that the total length of the river was 5588 kilometers. Later, it was found that the farthest source was the birthplace of kagera river in the East African Lake area. The North River flows into Lake Victoria, the largest lake in Africa, from the west through Tanzania, Rwanda and Uganda. The main stream of the Nile originates from this lake, which is called Victoria Nile. The river passes through Lake Keoga and Lake Albert, and it is called Albert Nile after flowing out. When it flows into the Sobat River, it is called the White Nile. Another Blue Nile, which originated in the highlands of central Ethiopia, joins the White Nile in Khartoum, Sudan, and then receives the last major tributary, atbara river, north of Dammeyer, and is called the Nile. In this way, the Nile meanders in an S shape to the northwest, flows through three waterfalls and flows into Nasser Reservoir. After leaving the reservoir and entering the Nile Delta via the Egyptian capital, the river divides into several tributaries and finally flows into the eastern end of the Mediterranean. On the left is the satellite image of the Nile. The green sector on the upper left is the Nile Delta, the long dark blue part in the middle is the Red Sea, and the winding line on the left side of the Red Sea is the Nile. There is an irregular wide section in the middle and upper part of the river in the picture, which is Nasser Reservoir, where the famous Aswan Dam is located. The Nile is characterized by frequent flooding. In northern Sudan, it usually starts to rise in May and reaches the highest level in August. After that, the water level gradually decreased, and the water level was lower from 1 to May. Although floods occur regularly, the amount of water and the time of high tide vary greatly. The reason for this phenomenon is the Blue Nile and atbara river, whose water source comes from seasonal rainstorm on Ethiopian plateau. More than 80% of the Nile's water is provided by the Ethiopian plateau, and the rest comes from the lakes in the East African plateau. When the flood comes, it will flood the farmland on both sides, and when the flood recedes, it will leave a thick layer of river mud and form fertile soil. Four or five thousand years ago, Egyptians knew how to master the flood law and make use of the fertile land on both sides of the strait. For a long time, the Nile valley is full of cotton fields and fragrant rice flowers. Between the Sahara desert and the Arabian desert, the winding Nile is like a green corridor, full of infinite vitality. This is a set of satellite images of the Nile before and after the flood season. April and August 2000 and May and August 20001year. This picture clearly shows that the river widened during the flood season.

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