Now days it would be done via satellite imaging.
The Nile River is the longest river in the world and is measured up to 6695 kilometers ( 4184 miles).
The longest river is the River Nile. The biggest river, measured by the amount of water that flows down it, is the Amazon.
Nile River
Egypt has only one river - the river Nile, the longest river in the world.
The nilometer measured the rise of the Nile River during floods. Knowing where the Nile River was going to flood was crucial for knowing where to plant crops and where to build houses.
Nile River
Egypt's Nile River is probably the most significant of these.
The Nile River.
The River Nile flows through Cairo, Egypt.
Nile River.
The River Nile flows through the Nile Valley.
The Nile River is in Africa. It is considered the longest river in the world being 4,258 miles long. The Nile River is divided into two main branches, the White Nile and the Blue Nile.