Aswan spelled "Assuan". Aswan is the ancient city of Swenett, later known as Syene, which in antiquity was the frontier town of Ancient Egypt facing the south. Swenett is supposed to have derived its name from an Egyptian goddess with the same name. This goddess later was identified as Eileithyia by the Greeks and Lucina by the Romans during their occupation of Ancient Egypt because of the similar association of their goddesses with childbirth, and of which the import is "the opener". The ancient name of the city also is said to be derived from the Egyptian symbol for "trade", or
Aswan Dam year. The annual crop consumptive use of water is about . Hence, the overall irrigation efficiency is 38/46 = 0.82 or 82%. This is a relatively-high irrigation efficiency. The field irrigation efficiencies are much less, but the losses are reused downstream. This continuous reuse accounts for the high overall efficiency. The following table shows that the equal distribution of irrigation water over the branch canals taking off from the one main irrigation canal, the Mansuriya Canal near Giza, leaves much to be desired: The salt concentration of the water in the Aswan reservoir is about , a very low salinity