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Excavating Zabid

Royal Ontario Museum Yemen Project Overview

Spate Irrigation and Water Delivery Systems

Edward Keall
Curator Emeritus
Royal Ontario Museum

Moving dirt in the dry wadi bed, as part of a small land-reclamation scheme

Spate Irrigation and Water Delivery Systems

Beginning in 1992, increasing attention was paid to the role of agriculture in support of Zabid’s urban economy. Water delivery systems for both the city and the irrigated farmland became a vital part of the Project’s enquiry, with an appreciation of the fact that seasonal spate water was diverted by barrages into a canal system for immediate distribution, rather than being held back by a dam. The modern system includes concrete-engineered devices, but the principle remains largely the same as it had been managed in medieval times. The system is dependent on the monsoon winds, which – in season –generate extensive thunderstorm activity in the highlands, and heavy run-off into the Tihamah wadis.


Land in different sections of the Wadi Zabid was allocated water diversion rights for different times of the year. An unexpected discovery ­– during work on cleaning and exposing decorations in the so-called al-Iskandariyyah mosque – was the exposure of an inscription, a waqf text that specified the expected harvest (and therefore tax revenue) that could be generated from the different areas in support of a madrasa.


In the dry wadi bed, the Canadian Mission documented devices that amounted to earthen banks mounded up at the edge of the flood-course, designed to reclaim land that had been eroded away. In time in this way, as fields were rebuilt, the flood sediments rose higher until they were eventually eroded away once more. It is surmised that the sharp bend in the bed of the Wadi Zabid, as it runs towards the city, is likely due to the force of a flood that seized the bed of one of the wadi’s canals – possibly at the time of the washing away of the famous al-Mujahidi barrage. An early 14th century Rasulid-era map of the wadi shows it flowing along a completely straight course.


Besides surface spate water, underground systems were constructed to deliver clean water to the city. The Zyadid/Najahid-era device was a plaster-lined conduit; in the Rasulid era it was one built of ceramic pipes set in a bed of masonry brickwork. Within the city itself, water was also drawn from wells, and directed along open conduits to mosque ablution pools and bath-houses; or carried in lead pipes to houses.


Dry bed of the Wadi Zabid in winter,

with diversion berms set in place pending the rainy season


A gentle, but steady steady flow of water in the wadi, two weeks after heavy rain in the highlands


A Rasulid-era drum-shaped feature, to encourage sediment settlement, and distribution of clean water along different pipelines


Interlocking ceramic water-pipes laid in a bed of masonry

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