Beni Isguen, M’zab, Algeria
The great Beni-Isguen Dam is also known as ahbas and this name has spread to the whole surrounding region. Upstream of the qsar, it is built over the bed of the N'tissa Wadi, spanning one of the narrowest gaps between the two hills that flank the palm grove.
The dam is 430 m long, 8 m high, 3 m wide at its base and 1 m wide at the top. It is divided into two main parts.
Firstly, the spillway and distributor, which is 77 m wide and runs down on a slightly diagonal path; 74 vertically set stones break the power of the water current and allow the umanas (flood water management commission) to measure the height of the floods from the level at each stone. At the top of the spillway a post (sham'a or candle) of predetermined height indicates a dangerous flood level. If the water rises to this height, an immediate alert is given to evacuate the whole palm grove and the qsar area further downstream.
The second part of the dam is the natural reservoir which feeds the ground water. Two wells dug out at the level of the dam accelerate and ease the feed to the ground water and so reduce the effect of evaporation caused by the extensive surface area of the stored water, especially during hot weather.
The great Beni-Isguen dam is situated upstream of the qsar in the bed of the N'tissa Wadi. It consists of two parts; the spillway, along which are set stones for measuring the water level and to give the alert in case of dangerous floods; and the reservoir in contact with the ground water via two wells.
Taken from regional written accounts.
Didillon, C. and Pierre D., Habiter le desert, les maisons mozabites, Brussels, 1986.
Rapport sur les sites et monuments de la vallée, OPU, Algiers, 1986.
Lakhdar Drias "Beni-Isguen Dam" in Discover Islamic Art, Museum With No Frontiers, 2017. 2017. http://www.discoverislamicart.org/database_item.php?id=monument;ISL;dz;Mon01;30;en
Prepared by: Lakhdar Drias
Copyedited by: Margot Cortez
Translation by: David Ash
Translation copyedited by: Mandi Gomez
MWNF Working Number: AL 39