Complex sentence: In Iraq, the Euphrates is known as Nahr al Furat and is only navigable by very shallow-draft boats, which can reach as far as the Iraqi city of Hit, located upstream and which is only above sea level.
Split into simpler sentences: In Iraq, the Euphrates is known as Nahr al Furat. Once it reaches Hit, the Euphrates is still only navigable by very shallow-draft boats, Hit located upstream and which is only above sea level.