Friday, September 23, 2011

Ancient Mediterranean Water Supply Networks Revived

Years of drought had dried up the ancient water supply networks existing around the Mediterranean Rim. However, with rainfall returning over the past 5 years, the hydraulic heritage has come to life again. The names of the tunnels that carry the revived streams -khettaras in Morocco, foggaras in Algeria or qanâts in Iran- evoke the trickling sounds of water. These underground infiltration galleries are the most characteristic and original illustration of local communities' recovery of ancestral schemes. As IRD researchers and their partners1 show, these water mines in the middle of the desert, most of which had been abandoned, have now been restored by oasis inhabitants.

These communities are now reinvesting in the maintenance of khettaras and in agriculture, especially young people returning to rural environments after experiencing unemployment in towns and cities. This is a risk owing to the uncertainties of climate, but fully assumed to revive collective action and to reappropriate the rules governing water-supply access, indeed in anticipation of possible new shortages in the years to come.

The ancestral hydraulic heritage which exists all around the Mediterranean Basin is finding renewed life. Over the past five years, the return of water is bringing back the old water supply amenities to their former status. An IRD research team and its partners1 have shown that the local communities are reinvesting these networks, abandoned during several years of drought.

The most typical, original and sophisticated examples of this revival are the underground2 infiltration galleries, tunnels known since Antiquity as khettaras in Morocco, qanât in Iran, foggaras in Algeria. These water mines are the result of an traditional technology, developed on a grand scale from the XIIth Century in North-West Africa to create artificial oases in the Sahara.

High-level technical know-how behind centuries-old schemes

The tunnels serve to conduct water from the groundwater body. The principle used for construction testifies to considerable knowledge and sophisticated technical mastery. It consists in digging into a hillside to create an underground conduit, far enough to meet a shallow aquifer. Set with a low downstream gradient, the conduit allows water to descend by gravity flow, with almost constant discharge, to emerge at the foot of the hill.

Observed from the ground surface, only a line of small characteristic cones of earth over several kilometres tells of the existence of such engineering works beneath our feet. They are the spoil removal shafts which mark the trace of the tunnel, about 30m away, and are used as access points for maintenance.

The example of Morocco

Length of the tunnels can range from 5 to 20 km for a height of 2 to 4m but scarcely 50cm wide. One example is in Tafilalet province of Morocco, in the Meknès area, where the khettaras have been better preserved. The research team focused their investigations especially on these. A total of 450 have been counted in this area. These conduits were dug from the end of the XVIIIth or early XIXth Century until 1950 and enabled a population of about 600 000, 75% of them living mainly from agriculture, to develop in this extensive area at the foot of the Atlas, hemmed in between the mountain and the Sahara.

Tunnel renovation

Modernization of public water networks during the second half of the past century, notably with dam construction, and the surge in private drilling have left the khettaras weakened. These modern networks have been superimposed on the traditional works, on the means of reinforcement or competition, and a great number of infiltration galleries were taken out of service. Then the periods of severe drought which hit in the 1970s and again from 1995 to 2005 in their turn dried up the khettaras. Five years ago, only a few dozen tunnels were still permanently in operation.

However, regular abundant rain has returned, since May 2006. The groundwater resource again feeds the catchment area upstream of some of the galleries which were partially or completely abandoned. The local communities then undertook to renovate them. In five years, at Jorf, in the west of Tafilalet, nearly 50 conduits have been put back into working order thanks to community initiatives. The local and regional water and political authorities are now also working towards the same objective and putting forward a rehabilitation scheme for khettaras.

This new boost for the communities' hydraulic heritage gives them the opportunity to reinvest in oasis-based agriculture, in particular involving young people returning from towns and cities mainly due to unemployment encountered there. Only recently, many young people started to come back to the oases to take on the restoration and maintenance of khettaras.

Like the communities living in the oases, the populations around the Mediterranean Rim are renovating the old water supply networks, in a similar way to those in the Moroccan High-Atlas, the Alps, Pyrenees or again in the mountains of Lebanon who are again injecting new life into the impressive terraced landscapes they have sculpted over the past centuries.

An uncertainty nevertheless remains: is the return of the water sustainable? A point difficult to ascertain according to the scientists. But this is where these rural societies are putting their stakes. To avoid any further individual groundwater extraction by unverifiable pumping, they are relaunching collective action to establish a new level of justice for access to water supplies… with the looming prospect of a possible new water shortage in the coming years.

Science Daily. 2011. "Ancient Mediterranean Water Supply Networks Revived". Science Daily. Posted: September 9, 2011. Available online:

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