The Nile River has an average depth of 26 to 36 feet. It can change significantly during periods of flood. In ancient times, the waters of the Nile rose and flooded the surrounding plains. The construction of the Aswan dam has largely ended this natural inundation.
The flooding of the Nile was crucial for the agriculture of ancient Egypt. The priests of ancient Egypt measured the Nile's level to predict the flood. While the average flood raised the river's water level about 6 1/2 feet, severe flooding brought a 39 foot rise in water level. The flooding of the Nile continued into the 19th century, with a 26 1/2 foot rise in water level noted in 1885.