Large scale water works are vital for the population of the oases. Before starting his daily work, every farmer, alone or with his family or his khemmas (sharecroppers), and the village community (qçar) must unite to secure water for their community. They need to maintain constant spring flow, to build basins (Tanoutfi) to increase the water volume flowing into the canals and into the fields, to build and repair dykes or small dams, and expand the khettaras (or foggaras), a succession of wells linked by underground canals leading to the irrigated fields. The canals should provide sufficient water for the upstream and downstream palm groves, according to the tradition and the water rights prescribed by ancestral contracts. Artificial lakes are created to store water for cattle and for years of water shortage.
Operation of the khettara irrigation system
The khettara or foggara represents an ancient sophisticated technique which enables underground water resources to be tapped for irrigation. Actually this method dates back thousands of years and has been adopted over a very large area stretching from China to Spain, throughout Persia, and as far as Latin America. Water systems like these are known by different names: the khettara or foggara of the Sahara desert, the qanat or kariz of Persia, the falaz of Arabia and the madrjirat of Andalusia. Similar water systems are also found in Peru and Mexico (hoyas) (Laureano, 2005). The first documented inscriptions of the qanat date back to the 7th century BC. In the Mediterranean, the qanat originated from Persia (Iran of today), and spread throughout the Middle East and North African semi-arid and arid regions, including Morocco.
The khettara system taps the groundwater table by means of a nearly horizontal tunnel which is dug over a long distance (normally 4-8 km but can reach even 15 km in length!). At regular distances (~10m apart), vertical shafts are dug which enable access to and maintenance of the main tunnel. The well-like shafts do not function as points for extracting water, but instead they are used for the aeration and condensation of atmospheric water. As the khettara’s main tunnel is constructed along a lower gradient than the terrain under which it lies, the tunnel becomes gradually shallower until it emerges aboveground at a distance of several kilometers far from the first well, which in certain cases can reach a depth of 150 m! (considering the tunnel is excavated under a hill or a mountain). The construction may also start from the settlement site inward, usually following the alluvial cone of a river or fossil wadi.
Unlike a feeder canal and the Iranian qanats, the Moroccan foggaras do not convey water from springs or underground pools, as their main tunnel usually does not reach deep groundwater resources (Laureano, 2005). Actually the foggara is fed with water primarily in the following ways:
- a. Through microflows in the sands: The sources of these microflows are mountainous areas which receive rainfall that may fall thousands of kilometers away from the foggara, and it may take ~5.000 years for these microflows to cover this distance!
- b. Through regular rainfall in the plain above the foggara: In this case the subsoil actually acts like a rocky sponge, draining off the upper layers of earth. Even in areas with very low precipitation, because of the enormous size of the basins, this water may be a significant contribution to the foggara outflow.
- c. Through condensation of atmospheric humidity: This is based on the phenomenon of “hidden precipitation” that is of primary importance in the desert ecosystem (due to this process organisms like gazelles, lizards and scarabs procure drinking water for their survival in the desert). Because of a temperature variation between day and night that can reach up to 60oC, a significant amount of night condensation is produced, that if managed properly can form sizable water reserves. Thanks to heat extraction at night, humidity is released into the sand, and the foggara reinforce this process acting as pumps that attract vapour. After sunrise the process is reversed whereby the heated air in the foggara rises through the shafts that are exposed to the burning temperatures of the desert, leaving behind water droplets retained in the soil and on the walls of the tunnel. These droplets are pulled by gravity from the outflow of the main tunnel. It has been calculated that by this process, in the desert, 4cm3 of water can be collected per square meter of surface area in only one night!
The condensed water, relying on gravity, eventually drains through the gently sloping main tunnel. In some cases, the outflow of a khettara is stored in a reservoir, or otherwise directly conducted from the drainage tunnel into a complex system of souguia channels to irrigate the fields. The palm grove of the oasis creates a microclimate suitable for crop production. It provides shade to allow vegetable growth and limits evaporation and transpiration from plants, and also attracts and collects moisture.
With proper maintenance, the khettara create a self-sufficient agriculture based on palm trees and olive trees, which in turn allows the growing of wheat, barley, maize, alfalfa, fruits and vegetables in enclosed gardens (plots or jennas). However, the khettara is more than an irrigation system; it embodies the traditional social structure of a qçar, enabling and regulating the social interactions that are based on the most precious element, freshwater. Thus, to understand the khettara it is necessary to explain the collective socio-political organization which prescribes how the water (and land) is allocated to qçar, families and individuals.
Khettara construction and maintenance
As is the case with river irrigation, the management and maintenance of the khettara is the responsibility of the jmâa. The jmâa is the collective management authority of each community and it includes representatives of every lineage within a qçar, who are chosen according to various criteria (nobility, wisdom, courage and wealth). The sharing of water is organised according to regulations that differ from qçar to qçar, depending on distribution methods, the water flow and the number of tribes and persons entitled to irrigate. The jmâa is also the body that chooses the chief of the tribe (amghar-n-tamazirt or amghar-n-taqbilte).
Traditionally khettaras are built by hand, by a small group of skilled labourers. The critical initial step is the identification of the water resource, usually located at the point where the alluvial fan meets the foothills of mountains (mountains receive more rain). A test well is dug to determine whether the resource and flow are ample enough to justify construction of a khettara. If the test is successful the route is laid aboveground and the excavation begins, either from the surface (destination) inwards to the slope of the hill, or vice-versa. The excavation crew is typically composed of 3-4 workers. Usually one person digs the horizontal tunnel with a hoe; another collects the soil with a shovel in a leather bag which is then collected by one or two other labourers on top (ground level) through the vertical shaft. The speed of construction depends on the width and height of the tunnel, the nature of the soil and the depth reached. It can range from 20m of horizontal tunnel per day (in soft soil at a shallow depth) that can drop to only 2m per day (in hard soil and at great depth). If the crew hits rocks, the khettara is abandoned!
In general, the jmâa decides on the maintenance and the repairs that need to be carried out in a khettara, resolves conflicts and approves sales, changes, rentals and sharing of water among owners. Each individual water owner of a khettara has the right to exploit the water-rights as he wishes, and has the right to sell, rent or mortgage the water to others. Although water is considered the property of co-owners, the entire village has free access to it for domestic use, guaranteed by the main canals (souagui) that cross each qçar. In return, all villagers must contribute to the maintenance of the foggaras. Owners must share the expenses for restoration work and the extension of the galleries that are necessary from time to time.
The collective maintenance works are organised under the authority of the water-chief (sraifi or amghar-n-waman), elected annually by the jmâa. In Morocco, all persons owning water rights are traditionally obliged to participate in the collective maintenance of the khettara, regardless of the amount of land and water owned. This maintenance is necessary quite frequently, since sediment accumulations in the khettara’s tunnel quickly lead to a decrease or even blockage of water flow. Maintenance generally consists of removing sediment from the khettara tunnel and from the main souagui. Also, the vertical shafts may need to be covered to keep sand out, and the horizontal tunnel needs to be inspected for erosion or cave-ins on a regular basis. Typically, each family donates one workman per day during maintenance operations. If the maintenance is done by outsiders, all owners are expected to contribute to their payment.
The water-chief divides the tasks among the workers allocating heavy tasks to the younger men and light tasks to the elders. For example, the older men assume tasks like cutting and removing branches and twigs which hinder the free water flow along the souagui. The younger men assume tasks such as removing accumulated sediments from the canals (souagui). To do this, each seguia is divided into three-metre sections (asfil), and each of these is cleared by two persons. Specific tasks are sometimes performed by specialized workers (mâalmin) in return for payment.
Any person who is not able to participate in collective labour must pay the worker replacing him or must prepare a meal for all the workers. If someone refuses to contribute entirely, he can be fined by the water-chief or punished by the jemâa with social exclusion.
Day to day management
The distribution of water is achieved by permanent rotation, day and night, and the palm grove must be divided into separate sectors. The distribution of irrigation water is in the hands of a qualified person with a casting vote for water issues, known as the Sraifi. He is often chosen by the jmaâ, after a meeting with the owners and water users, for a specific length of time, which is usually extensible. Water management is ruled by common law, developed by the population itself. The unit of measurement of water shares (the kharrouba) is 45 minutes of flow from the spring. By using water storage basins and various distributing channels, the Sraifi makes sure every user is served through secondary or tertiary channels going in all directions in the oasis. The Sraifi also oversees spring water stocked in large basins and distributes it to entitled persons, through specific canalizations, according to an irrigation cycle that varies between 7 days in the summer and 15 days in the winter.
As the measurement unit adopted, the kharrouba has solved most of the conflicts between owners and users because of the flow variation of the sources and the day/night variations according to the seasons.
The water clock… (tighirte)
Regarding the actual water measures, the community has created precise techniques to delimit water ownership. These techniques vary from natural delimitations, such as day and night water property, to man-made instruments. One such instrument, a water clock, the tighirte was particularly useful during the night or on sunless days, when shadow measurement was not possible.
As there were no watches in the old times, in order to measure the Kharrouba (or tanast) the inhabitants used a hemispherical shaped copper tool called the tighirte. It is a graduated container with a tiny hole at the bottom that can contain more or less 1.5 litres of water. The Sraifi places the tighirte over a container filled with water, it floats while water enters from the hole until it sinks. The hemisphere then hits the bottom marking the time corresponding to a Tanast or a Kharrouba.
The risks of maintenance today
Nowadays, with the weakening effective power of the traditional jemâa and the decreasing economic role of agriculture, more and more people are evading their collective obligations. Common law, which used to regulate collective work, is becoming increasingly difficult to enforce. Young people especially, no longer accept to participate in collective maintenance work and no one has the power to oblige them to do so. The declining interest in and motivation for agriculture has also contributed to a decline in the collective maintenance of the khettaras.
Another crucial factor contributing to the decline of the khettaras in Morocco appears to be the installation of numerous motor pumps since the 70s, and the ensuing over-pumping that has caused a lowering of the water tables therefore rendering the khettaras useless. Both these factors reinforce each other as, due to the lowflow in the khettaras and their subsequent diminished agricultural importance, the motivation to maintain them will continue to decline and motor pumping will be further encouraged. In this framework, the future maintenance of the khettaras and the irrigation system is becoming increasingly difficult to guarantee.