Rivers in flood

This lesson asks you to describe the patterns and physical characteristics of major rivers and water systems. The museum offers accounts of the Nile, the Euphrates and the Tigris from medieval sources; your class adds lakes, oceans and drainage basins from other regions. ¹

Notice how each account measures a river: in cubits, by season, against what came before. Ask what you would need to draw the river's yearly pattern as a graph.

In 329 the Euphrates rose eleven cubits and burst out by Anbar, sweeping villages under. The water poured through al-Sarat toward Baghdad into the western quarter's streets until Bab al-Anbar street was submerged and not a house of it left standing. Buildings collapsed onto al-Sarat, the iron bridge of al-Sarat fell, part of the Daylij canal broke, and the Tigris rose eighteen cubits in May and June ². This is the record's account from Ibn al-Jawzi's al-Muntazam, and the record cites page 608 of that book for it. Cubits are also the units on the Nilometer of Rawda: its column is divided into nineteen cubits, and the sixteenth-cubit mark stands for the ideal flood level ³. Yeomans says its readings were essential in setting irrigation policy ⁴.

The Nilometer's column marks the sixteenth cubit as the ideal level of the Nile's flood, while Ibn al-Jawzi simply says the Euphrates rose eleven cubits and the Tigris eighteen. Why does a number of cubits tell you something about the Nile year but not, by itself, about the Euphrates year? What else would you need to know?

• The Nilometer of Rawda Island: the stone-lined pit and the column that gauged the Nile's flood.
• The Euphrates flood and the ruin of Bab al-Anbar: the account of the rivers' rise in 329.
• Baghdad: the city whose western quarter the water reached.

Read the Nilometer of Rawda and the Euphrates flood of 329 AH. Sketch a line for one year of the Nile's level, marking the ideal flood, and describe in two sentences what a flood would do to the land and what its absence would do.