Khettara

An underground water gallery used to convey groundwater from a mountain aquifer to the surface in an oasis. The technique is widespread across the arid regions of North Africa, the Middle East, and Central Asia, where it is variously called qanat (Persian), foggara (Algerian Arabic), or khettara (Moroccan Arabic). The khettara system underlies many of the historical southern Moroccan oases.

In construction a khettara consists of a series of vertical access shafts (ʿuyūn, "eyes") sunk at intervals of typically 10 to 30 m down to the underlying water table at the apex of an alluvial fan; the shaft floors are then connected by a gently inclined gallery that conveys water by gravity to a surface outlet at the head of the irrigation network. A single working khettara may extend several kilometres and require continuous maintenance to clear silt, repair shaft linings, and keep the gallery roof intact. Communal management — typically by the amin n waman under the authority of the jma'a — distributes water shares (nuba) on a rotational time-based system through the seguia network. Many southern Moroccan khettaras have fallen out of use in the past half-century, displaced by motorised pump wells that have lowered the water table below the level of the gallery outlet, with cascading consequences for the dependent palmeraie.