Editing Nilometer (section)

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{{Short description|Structure for measuring the Nile River's clarity and water level}}
[[File:Cairo Nilometer 2.jpg|thumb|Measuring shaft of the nilometer on [[Roda Island]], Cairo]]
A '''nilometer''' is a structure for measuring the [[Nile]] River's clarity and water level during the [[Flooding of the Nile|annual flood season]] in Egypt.<ref name="H" /> There were three main types of nilometers, calibrated in [[Egyptian cubits]]: (1) a vertical column, (2) a corridor stairway of steps leading down to the Nile, and (3) a deep well with a [[culvert]].<ref name=H/> If the water level was low, the fertility of the floodplain would suffer. If it was too high, the flooding would be destructive. There was a specific mark that indicated how high the flood should be if the fields were to get good soil.<ref name="H">{{cite encyclopedia |encyclopedia= Encyclopaedia of the History of Science, Technology, and Medicine in ... |title= Nilometer |author= Helaine Elsin |page= 1753 |date= 2008 }}</ref><ref name="Fagan2010">{{cite book|author=Brian Fagan|title=The Great Warming: Climate Change and the Rise and Fall of Civilizations|url=https://books.google.com/books?id=dpUDCcbmZJIC&pg=PT167|date=1 August 2010|publisher=Bloomsbury Publishing|isbn=978-1-59691-780-4|page=167}}</ref>

Nilometers originated in [[pharaonic]] times, were also built in Roman times, and were highly prevalent in Islamic Egypt in [[Rashidun Caliphate|Rashidun]], [[Umayyad Caliphate|Ummayad]], [[Abbasid Caliphate|Abbasid]], [[Tulunids|Tulunid]], [[Mamluk Sultanate|Mamluk]], [[Muhammad Ali dynasty|Alawiyya]] and [[History of republican Egypt|Republican]] periods, until the [[Aswan Dam]] rendered them obsolete in the 1960s.