The Aghlabid Pools

The Aghlabid pools and some fifteen others were located outside the wall of the town of Kairouan, in front of the Tunis gate at the north. Unlike other major towns of the time that lay on or near rivers, or near abundant sources of water, the supply of drinking water in Kairouan was a source of constant concern. Thanks to the ingeniousness of the hydraulic engineers of the town the problem was partially solved by the construction of several installations, the most significant of which are the pools.

The pools were constructed under the reign of Prince Abu Ibrahim Ahmad in 862. Khalaf al-Fata, his emancipated slave, supervised the building of the reservoirs whose surface is 11,000 m² and which contain up to 53,000 cubic metres of water. The Aghlabid Pools comprise a small sedimentation pool, a large storage pool and two water catchment cisterns. The small pool, known as Al-Fisqiya (the reservoir) is in the shape of a 17-sided polygon. It is not circular, as the Andalusian geographer Al-Bakri (d. 1094) maintained. The water settles in the small pool where it rids itself of its impurities. When a certain level is reached, it is transferred to the large pool through an opening known as esarh (the outlet). The large pool, also a polygon shape, is 4.8 m deep. In the middle of this pool stands a polylobed pillar, formerly topped by a dome, which was an area where the rulers would relax. The two pools are supported both from within and without by rounded buttresses made of rubble. The large pool has 64 interior buttresses and 118 exterior buttresses; the small pool has, respectively, 17 and 26. The cisterns, linked to the large pool at the south, are covered by barrel vaults supported by arches borne on pillars.

The pools were originally supplied mainly when the water rose in the tributaries of the Marguellil wadi through a system of drainage comprising pipelines and small weirs. Later, under the reign of the Fatimid Caliph al-Mu'izz, in 961, an aqueduct was built to supply the pools with drinking water from the Chrechira, located 40 km west of Kairouan.

This fascinating, large-scale monument subtly combines aesthetics with function. The significant role it played in the struggle of the inhabitants of Kairouan against thirst and drought nevertheless enabled the engineers to express their art in a way that was both majestic and sober.

The principle of catching rainwater in cisterns and covered pools was already used in Syria, in the Humayma region and along the route pilgrims took. Princess Zubayda, wife of Caliph Harun al-Rashid (r.786–809) had a pipe ten leagues long built to take water to Mecca during a severe drought.

It was commendable that the Ifriqiya region developed such a system, building impressive hydraulic facilities that were unique in the Mediterranean world. The prototype of the Aghlabid Pools spread throughout the Ifriqiya geographical region from Tunis in the north to Gafsa in the south. The forms were varied. The most well-known is the pool of the al-Bahr Palace in Raqqada. This rectangular pool was built in 905 by the Aghlabid prince Ziyadat Allah III. The rainwater collection system continued to be used in Tunisia until the contemporary period. From Ifriqiya it spread to the Maghreb, particularly to Morocco, in the Almohad, Marinid and Alaouit times. An example is the large pools of the noria of Meknes, built by Sovereign Mawlay Ismail (r.1672–1727).