Flooding of the Nile

The flooding of the Nile (commonly referred to as the Inundation) and its siltdeposition was a natural cycle first attested in Ancient Egypt. It was of singular importance in the history and culture of Ancient Egypt. In modern Egypt, governments began building flood management infrastructure during the 19th century. These efforts continued throughout the 20th century. In 1970, the annual flooding of the Nile ceased with the completion of the Aswan High Dam.

The river's predictability and annual deposits in the Nile Valley and Delta made for extraordinarily rich soil—classified today as alluvium on a bed of entisol— enabling the Egyptians to build an empire on the basis of its enormous agricultural wealth and surpluses of cereals which could be stored or traded. Egyptians were one of the first groups of people to practice agriculture on a large scale. This in turn was only possible with their innovation of surface irrigation, also called "basin irrigation", which finally gave rise to the form of Ancient Egyptian agriculture that persisted into the 20th century. Their farming practices allowed them to grow surpluses of both cereals—especially the staple cropswheat and barley—and industrial crops—such as flax for weaving into linen and Nile grass for manufacture into papyrus. By the time of Roman rule, Egypt was one of the most significant sources of wheat in the entire Roman Empire.

Egyptians have celebrated the flooding since at least early antiquity. Today the annual flooding is commemorated by a two-week holiday called , beginning on August 15. It is also celebrated in the Coptic Church by ceremonially throwing a martyr's relic into the river, giving it the name "The Martyr's Finger" (Coptic: ⲡⲓⲧⲏⲃ ⲛⲙⲁⲣⲧⲏⲣⲟⲥ, Arabic: Esba` al-shahīd).