
A picture of the Nile River during flood season; prior to the the 1970 construction of the Aswan Dam, the Nile would rise to heights of 30 feet, and last for 150 days. This phenomena is the basis for all the world's flood myths, via the water god Nu (Nun) turned, MaNu (VishNu), i.e. MaNu's flood, Noah, i.e. Noah's flood, etc.

A picture of the Nile River during flood season; prior to the the 1970 construction of the Aswan Dam, the Nile would rise to heights of 30 feet, and last for 150 days. This phenomena is the basis for all the world's flood myths, via the water god Nu (Nun) turned, MaNu (VishNu), i.e. MaNu's flood, Noah, i.e. Noah's flood, etc.

In geography, Nile River is a north-flowing river, predominately located in Egypt, the world’s largest river, behind the Amazon River, whose tributaries are the Blue Nile, originating from Lake Tan, in Ethiopia, and the White Nile, originating from Lake Victoria, in Kenya and Tanzania.

Helical rising | Flood
In Jun, in Egypt, the Nile River, owing to snow melting in the Ethiopian mountains, begins to flood, rising to heights of 30 feet, lasting 150-days.

In 450BC, Herodotus, in his History (2.19.2), stated that the Nile rises at the summer solstice, and after 100 days falls again. [4]

On Jun 25, the helical rising of Sirius, previously absent for 70-days, occurs, which marks the start of the annual Nile River flood. [2] As the star Sirius was associated with the goddess Isis, to the effect that the star seems to follow the Orion constellation, in the latter months of the year, as it perceptually "rises" as a human figure to a vertical orientation in the sky, the cultural story was common that the tears of Isis caused the Nile to flood:

“The Egyptians hold the festival of Isis at the time when they say she is mourning for Osiris. At that time the Nile River begins to rise, and it is a common saying among the natives that it is the tears of Isis that cause the river to rise and water the fields.”
— Apuleius (c.165AD), Eleventh Book; cited by Wallis Budge (1904) [5]

In 1970, the Aswan High Dam was completed, which ended the summer floods and their renewal of the fertile soil, fundamentally changing farming practices.

Egyptian mythology
The Egyptians believed that the Nile River was mirrored in the sky by the Milky Way, as shown below (Ѻ), and the three pyramids at Giza were built to mirror the belt of the Orion constellation, who they considered the god Sah (astral body) or Osiris:

The flooding of the Nile, the helical rising of Sirius, and the re-kindling of the Sun on Dec 25 formed the core of Egyptian mythology.


A diagram (Ѻ)(Ѻ) showing how the Egyptians considered the Nile River to be a mirror representation of the Milky Way.

A diagram (Ѻ)(Ѻ) showing how the Egyptians considered the Nile River to be a mirror representation of the Milky Way.

According to one account, it was believed, by the Egyptians, that the annual flooding of the Nile River was caused by Isis weeping for her husband. [3]

“Who is there that does not know that the vapor of the sun is kindled by the rising of the dog-star [Sirius]? The most powerful effects are felt on the earth from this star. "When it rises, the seas are troubled, the wines in our cellars ferment, and stagnant waters are set in motion. There is a wild beast, named by the Egyptians Oryx, which, when the star rises, is said to stand opposite to it, to look steadfastly at it, and then to sneeze, as if it were worshiping it. There is no doubt that dogs, during the whole of this period, are peculiarly disposed to become rabid.”
— Pliny the elder (77AD), “On the Rising of the Dog Star” [1]

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Christian mythology
At a certain point in the annual flood cycle, the Nile turned "red colored", owing, supposedly, to he red mud from the mountains. In the Bible, this is told as the story in Exodus 7:20 (Ѻ) of Moses turning the Nile to blood via the action of a miracle.

Muslim mythology
In 1904, Wallis Budge summarized things as follows: [1]

“The ancient Egyptian festival has its equivalent among the Muhammadans in that which is celebrated by them about Jun 17, and is called Lelet al-Nukta, i.e., Night of the Drop, because it is believed that on that night a miraculous drop falls from heaven into the Nile and makes it to rise.”

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Quotes
The following are related quotes:

“If I now ask you: ‘How, exactly, did the Dracula myth come about? Why? Who refashioned and propagated it? Why did they base it on Vlad mythology?’, we run into the same type of quagmire; certainly Vlad was a real person, prior to his transformation into the myth of Dracula, just as the annual Nile River flood is a real phenomenon, prior to its transformation into the myth of Noah and the Biblical flood, but to track down the specifics of ‘who’ and ‘why’, particularly in the latter example, wherein exact documentation is less readily available, is a big tossup.”
— Libb Thims (2014), “Hawking-Faraday Paradox” (Ѻ), Hmolpedia tread (#9), Oct 8.

“In order to understand hmolscience, one has to understand 100 percent that the Bible, and related derivatives, i.e. Quran, Rig Vida, Buddhist scriptures, etc., is but a collection of ancient proverbs, and semi-modern morals, i.e. rules for right and wrong, anchored into a proto-scientific mythological framework, framed within a tale of humans created from clay, amid a cyclical Nile river flood sun rebirth cosmology.”
— Libb Thims (2016), “mental note”, arisen while pausing amid doing bench and shoulder press sets, while looking at the parallel Bible sitting on the book shelf, 1:46 PM CST Feb 20

References
1. Budge, Wallis. (1904). The Gods of the Egyptians, Volume Two (pgs. 47). Dover, 1969.
2. Sirius – Wikipedia.
3. Bob. (2015). “Temple of Isis on Philae Island Aswan” (Ѻ), Blogspot, Jun.
4. Cicero. (45BC). The Nature of the Gods (Introduction, translation, and notes: Patrick Walsh) (pg. 189). Oxford University Press, 1998.
5. Budge, Wallis. (1904). The Gods of the Egyptians, Volume Two (pgs. 216-17; Isis weeping, pg. 219). Dover, 1969.

External links
● Nile River – Wikipedia.