The emergence and sustainability of life in the oases of the M’Zab in the Algerian Sahara is strongly linked to the mobilization of multiple water resources. The pioneers of the region had thought out and implemented, as early as the 11th century, an ingenious circular hydraulic system, which combined the use of surface and groundwater resources. This system has been continuously adapted to changes in the socioeconomic and climatic contexts. The circularity of this system materializes through a system of transport, sharing, and storage of water resources in the phreatic aquifer. This system is articulated around the ancestral social organization for distribution, allocation and storage of water.

This system was grafted on: i) an agro-ecological organization combining agriculture with livestock production, allowing the recycling of organic matter; ii) animal energy use for agricultural production and transport, and; iii) waste recycling nutrients, crop biomass and water within production systems, that increases the efficiency of use resource and minimizes waste, waste and pollution, especially with the use of dry toilets. However, the promotion of new forms of Saharan agriculture oriented toward economic profitability outside the old oasis in the so-called extensions, since the 1980’s, has questioned this circular system. At first glance, this rupture materializes through i) irrigated monoculture from little renewable groundwater; and ii) the reception of surpluses of (untreated) domestic water and irrigation in the phreatic aquifers, in addition to flood waters.

Thus, if these new forms of agriculture are generally very profitable, their environmental impacts are increasingly criticized. In Oued Souf, for example, there is pollution and a rise of water table in some places, which causes serious environmental and / or health problems (Côte, 1998). Faced with its environmental vulnerabilities, localized initiatives are beginning to emerge in order to promote more sustainable forms of agriculture in the Sahara. These include, for example, water conservation practices, the implementation of small groundwater recharge schemes, agro-ecological practices on some farms, organic farming or permaculture, or the recycling of organic or plastic waste. However, these initiatives are poorly documented and don’t receive much attention. Based on what emerged during our field missions, coupled with bibliographic reading, we formulate the hypothesis that the four links of the circular system (Water-Agriculture / Livestock-Waste-Energy) described above and which interact with each other, are a priori pillars of the resilience of the M’Zab oases. In a new socio- economic and agricultural context, we formulate the following question: How can the concept of circularity, applied to different links of the oasis system and their interactions, inspire a sustainable development of agriculture in the new forms of Saharan agriculture? To answer the research question, we propose three methodological steps:

• Sustainability analysis of the farms in different agricultural areas, by determining the degree of circularity that exists for each link of the system in these spaces through the IDEA method;

• Multi-scalar and multidisciplinary analysis of water circularity at the scale of farm and irrigated territory;

• Participatory modeling of scenarios for Saharan agriculture transformations.

Sensor well, the flood waters are collected and put into the well to recharge the water table - © SAIDANI Amine