The High Dam is considered the greatest and the largest engineering project in the twentieth century in terms of architectural and engineering side surpassing other global giant projects. The High Dam was built to protect Egypt from high floods that was overflowing on the country and deluging large areas or went in vain in the Mediterranean.
The Importance of High Dam Building:

Egyptians realized the importance of the Nile since ancient times; annual storage projects such as Aswan reservoir and The Jebel Aulia Dam were established to control the Nile river variable revenue in addition to Qanater on the Nile to organize irrigation.
However, the annual storage was only partial treatment to organize and control the Nile since the river revenue greatly differs from year to year as it may reach about 151 billion cubic meters or fall to 42 billion cubic meters annually. This great disparity from year to year makes reliance on the annual storage is extremely dangerous as it may endanger agricultural lands to barrenness in low-revenue years.

So, thinking tended to create a huge dam on the Nile to store water in high - revenue years to be used in low - revenue years. The High Dam establishment, the first project of continual storage on the level of the Nile Basin, was implemented within the Egyptian borders.