page_title: Nilometer
section_title: Designs
hierarchical_section_title: Nilometer / Designs
caption_attribution_description: Deutsch: Nilometer an der Südostseite der Insel Elephantine in Assuan, Ägypten
context_page_description: A nilometer was a structure for measuring the Nile River's clarity and water level during the annual flood season. There were three main types of nilometers, calibrated in Egyptian cubits: a vertical column, a corridor stairway of steps leading down to the Nile, or a deep well with culvert. If the water level was low, there would be less food. If it was too high, it would be destructive. There was a specific mark that indicated how high the flood should be if the fields were to get good soil.
  Between July and November, the reaches of the Nile running through Egypt would burst their banks and cover the adjacent flood plain.
  When the waters receded, around September or October, they left behind a rich alluvial deposit of exceptionally fertile black silt over the croplands. The akhet, or Season of the Inundation, was one of the three seasons into which the ancient Egyptians divided their year.
  The annual flood was of great importance to Egyptian civilization.
context_section_description: The simplest nilometer design is a vertical column submerged in the waters of the river, with marked intervals indicating the depth of the water.
  One that follows this simple design, albeit housed in an elaborate and ornate stone structure, can still be seen on the island of Rhoda in central Cairo (30.0069°N 31.2250°E).  This nilometer visible today dates as far back as AD 861, when the Abbasid caliph al-Mutawakkil ordered its construction, overseen by the astronomer Alfraganus. It was built on a site occupied by an earlier specimen which was seen by the Syrian Orthodox patriarch Dionysius of Tel Mahre in 830. This prior nilometer had been ordered in AD 715 by Usāma b. Zayd b. ʿAdī, who was in charge of collecting the land tax (kharaj) in Egypt for the Umayyad caliph Sulaymān ibn ʿAbd al-Malik.
  The second nilometer design comprises a flight of stairs leading down into the water, with depth markings along the walls.
  The best known example of this kind can be seen on the island of Elephantine in Aswan, where a stairway of 52 steps leads down to a doorway at the Nile. This location was also particularly important, since for much of Egyptian history, Elephantine marked Egypt's southern border and was therefore the first place where the onset of the annual flood was detected.
  The most elaborate design involved a channel or culvert that led from the riverbank – often running for a considerable distance – and then fed a well, tank, or cistern. These nilometer wells were most frequently located within the confines of temples, where only the priests and rulers were allowed access.
  A particularly fine example, with a deep, cylindrical well and a culvert opening in the surrounding wall, can be seen at the Temple of Kom Ombo, to the north of Aswan.
caption: Nilometer on Elephantine Island
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