The Nile flows into the sea by an extensive delta with an area 22 000 km2. It begins in the northern suburbs of Cairo, which it separates from the sea 175 km of land formed by the river. It reaches width along the seashore 220 km. The Nile splits into two arms: Damietta in length 240 km to the east and the length of Rosetta 325 km to the west. Between them there is a tangle of channels, irrigation ditches, irrigation systems and roads and railways. For thousands of years, the Nile valley and the delta have been a land of abundance and fertility. It owed it to the fertile silts brought by the annual floods. They were of great importance for agriculture – fertilized the soil, but they were also used as building materials, from which whole villages arose. This oasis in the sands of the neighboring deserts is densely populated and intensively developed. Most of the surface is covered by cotton fields, sugar cane, rice and wheat.
The upper course of the Nile is located in the humid subequatorial climate zone with a mountain variety. There are two rainy and two dry seasons. In summer, rainfall is high (about 1500 mm per year) and decrease with increasing latitude. The flows of this section of the Nile are balanced thanks to natural retention reservoirs – Victoria lakes, Kioga i Alberta. Regardless of the amount of rainfall, they provide a constant amount of water. Fluctuations in water levels are marked on the Mountain Nile. Due to intensive evaporation, it loses significant amounts of water in the Sudd floodplains. Despite the adoption of a large tributary of the Bahr al-Ghazal, the water level in the river in summer is falling so low, that the White Nile would not have been able to break through the desert sands in the summer heat. Right-hand Abyssinian tributaries come to the rescue, the most important of which is the Blue Nile. They come from an area within the same climate as the headwaters of the Nile. During summer rains, they are supplied abundantly and then carry the most water. It is them that cause the flooding of Egypt at the turn of summer and autumn (from August to October). After the construction of the Great Aswan Dam, the flows became much more even, and the controlled flooding is not as large as it was originally.
There are great dams and reservoirs all along the Nile. The most famous and at the same time one of the largest hydrotechnical structures is the Aswan Hydrotechnical Node. It is made up of the Great Aswan Dam (length 3600 m and height 111 m), Lake Nasera and a hydroelectric plant, wherein 12 turbines generate energy with total power 2100 MW. Initially, the investment brought only benefits: inundation control has averted the risk of catastrophic floods, year-round irrigation made it possible to increase the area of cultivated fields by 800 thousand. ha, while cheap electricity influenced the development of Egypt's industry. Year-round navigation on the Nile up to the border with Sudan has also become possible. However, human interference with nature also had negative effects. After some time it was observed, that precious river sediments, instead of fertilizing the Nile valley, are deposited in the reservoir. This resulted in the depletion of soils and the need to use artificial fertilizers. In addition, the delta area began to recede, because the destructive forces of the sea remove more material from it than the river can carry.