The Flooding of the Nile
The Nile used to flood once every year during the inundation season, what the Egyptians called Akhet, between June and September. It flooded onto the desert land because of of the rain and melting snow causing a torrent of water to invade the river's banksfrom the Ethiopian Mountains. Now, the Nile doesn't flood anymore because of the construction of the Aswan dam in the 1960's (see page 11).
The picture above was when the Nile flooded.