Editing Euphrates (section)

=== Discharge===
The Euphrates receives most of its water in the form of rainfall and melting snow, resulting in peak volumes during the months April through May. [[Discharge (hydrology)|Discharge]] in these two months accounts for 36 percent of the total annual discharge of the Euphrates, or even 60–70 percent according to one source, while low runoff occurs in summer and autumn.<ref name=isaevmikhailova384/><ref name=neweden2006a91>{{harvnb|Iraqi Ministries of Environment, Water Resources and Municipalities and Public Works|2006a|p=91}}</ref> The average natural annual flow of the Euphrates has been determined from early- and mid-twentieth century records as {{convert|20.9|km3}} at Keban, {{convert|36.6|km3}} at [[Hīt]] and {{convert|21.5|km3}} at [[Hindiya]].<ref name=isaevmikhailova385>{{harvnb|Isaev|Mikhailova|2009|p=385}}</ref> However, these averages mask the high inter-annual variability in discharge; at [[Birecik]], just north of the Syro–Turkish border, annual discharges have been measured that ranged from a low volume of {{convert|15.3|km3}} in 1961 to a high of {{convert|42.7|km3}} in 1963.<ref name=kolars47>{{harvnb|Kolars|1994|p=47}}</ref>

The discharge regime of the Euphrates has changed dramatically since the construction of the first dams in the 1970s. Data on Euphrates discharge collected after 1990 show the impact of the construction of the numerous dams in the Euphrates and of the increased withdrawal of water for irrigation. Average discharge at Hīt after 1990 has dropped to {{convert|356|m3}} per second ({{convert|11.2|km3}} per year). The seasonal variability has equally changed. The pre-1990 peak volume recorded at Hīt was {{convert|7510|m3}} per second, while after 1990 it is only {{convert|2514|m3}} per second. The minimum volume at Hīt remained relatively unchanged, rising from {{convert|55|m3}} per second before 1990 to {{convert|58|m3}} per second afterward.<ref name=isaevmikhailova386>{{harvnb|Isaev|Mikhailova|2009|p=386}}</ref><ref name=neweden2006a94>{{harvnb|Iraqi Ministries of Environment, Water Resources and Municipalities and Public Works|2006a|p=94}}</ref>