Today, with the world on the brink of ecological collapse, the traditional knowledge of our predecessors can really teach us how to interact with the environment in a more ?sustainable? way, using natural resources without depleting them. So what exactly do we mean by traditional knowledge and techniques? We might define traditional knowledge as the sum of local solutions and techniques, which include farming practices, models of water management, everyday habits, artifacts and even behavior and spiritual values. But let?s take some concrete examples. Think for example of the underground drainage (passageways to take water underground and create oases in the desert).

The Saharan oases :

The oases in the Algerian Sahara illustrate effectively how man has succeeded in surviving hostile conditions. Over the centuries, an efficient and sustainable irrigation system has been applied that has allowed the inhabitants of the oasis to live in conditions of extreme aridity while respecting the particular properties of these unstable ecosystems. However, over the course of the past few years, the Saharan oases have come to experience strong demographic growth along with the intensification of agricultural production. In this particularly fragile environment, the inhabitants of the oases tend to forgo traditional knowledge regarding water resources. Also, modern techniques to pump water from underground sources dry up the groundwater reserves in a way that is irreversible. For this reason, the rehabilitation of the foggaras, a system of traditional irrigation, is recommended in south-eastern Algeria.

The fouggaras :

The foggaras are manmade underground galleries that harvest water. They effectively capture water found at depth and transport it to the surface. Underground piping runs almost horizontally and transports the groundwater to the oasis by means of a slight incline of one or two millimetres per metre.

For the system to work, the oasis must be located in a valley or at the foot of a rift, so that it is below the level of the underground source. The Adrar oases are all located below the plateau of Tadmait where the groundwater source flows. The first wells are dug upstream from the oasis. The gradual sloping of the galleries reduces the speed of the flow, thus preventing the water from dragging the soil with it, which would result in the erosion of the galleries. This ingenious method uses gravity to transport water throughout the year.

The materials used for the construction of the foggaras come from the surrounding area. Blocks of stone are cut, clay and straw are combined to make a cementing mix and palm trunks are used to consolidate the underground galleries. The average length of the galleries is 2.5 km and they include vertical wells found every 20 to 30 metres used to aerate and repair the foggaras.

The foggaras allow for the passive transport of water, relying only on the force of gravity. Water is captured underground and flows under the earth, which prevents its evaporation, until it is close to the oasis where it flows into an open-air canal (seguia). A small triangular basin (quasri) collects water that arrives at the oasis by way of the seguia .

With the help of a stone device in the shape of a comb (kesria), the water continues to irrigate the oasis . The community sets up a ?water assembly? where decisions are made on who receives how much water among those who possess water rights in response to variations in water supply. Everyone is free to exercise his or her rights and demands for water. The ?water deciders? are then responsible for the distribution of water.

the foggaras had been progressively  abandoned: today they are being restored

The kesria permits water distribution in the oasis

A water master from the Algerian oasis of Adrar, showing the perforated artifact to measure the water flows for its distribution