Short answers, pulled from the story.
The Euphrates is about 2780 km long, the longest river in West Asia and the fifteenth-longest in Asia. It originates in Turkey and flows through Syria and Iraq, joining the Tigris in the Shatt al-Arab before reaching the Persian Gulf. Its drainage area of 440000 km2 covers six countries.
The Euphrates begins at the confluence of the Kara Su, or Western Euphrates, and the Murat Su, or Eastern Euphrates, 10 km upstream from the town of Keban in southeastern Turkey. Both source rivers rise northwest of Lake Van, at elevations of 3290 m and 3520 m above sea level.
The English name Euphrates comes from the Greek Euphrátēs, which was adapted from older Elamite and Sumerian writing. Tamaz V. Gamkrelidze and Vyacheslav Ivanov suggest it derives from a proto-Sumerian word for copper, because the river was used to transport copper ore on rafts.
The Euphrates has declined because of dam construction and increased withdrawal of water for irrigation, beginning with the first dams in the 1970s. In 2021, Iraq's Ministry of Water Resources reported the river could dry out by 2040 due to climate change and droughts.
The Southeastern Anatolia Project, known as GAP, is Turkey's plan to harness the Tigris and Euphrates for irrigation and hydroelectricity. When complete it will include 22 dams and 19 power plants, covering 75000 km2 and affecting about 7 million people. Its largest dam is the Atatürk Dam, completed in 1992.
In Islamic tradition, a hadith of Muhammad states the Last Hour will not come until the Euphrates uncovers a mountain of gold over which people fight. In the Christian Bible, the river's drying in Revelation 16:12 foretells the Second Coming, and the river Phrath in Genesis 2:14 is named among the rivers of Paradise.
Disputes arose because upstream dams reduced flow to downstream countries. In 1975, filling the Keban and Tabqa reservoirs during drought cut flow into Iraq, prompting Iraq to threaten bombing the Tabqa Dam before Saudi Arabia and the Soviet Union intervened. On the 16th of May 2014, Turkey cut off the flow completely at the Turkish-Syrian border.