Farmers' behaviours and trends in agricultural water demand: The case of the irrigated Mitidja plain (Algeria)

The work presented in this paper is based on decisions related to farm irrigation practices on the Mitidja Plain in Algeria. In order to determine irrigation water demand evolution, attempts are made to identify the important parameters on which farm irrigation decision-making is based. The resulting global water demand trends taking farmers' behaviours into account are then characterised. The Mitidja plain covers 1400 km² and provides Algiers with much agricultural produce. The irrigated area covers over 60% of the plain, and consists of citrus, fruit tree and greenhouse crops. Furrow irrigation is still the most common irrigation practice. With only 20% of the farms' water demand satisfied by the collective distribution network, groundwater represents the most reliable resource with regard to availability, quantity and quality of water for farmers. The aim of this work is to assess changes in farm water demand (concentrating on cooperative farms which occupy 80% of the plain), taking into account farm diversities, farmers' behaviours, as well as current water supply constraints. Within the cooperative farms, there is often conflict between assignees, which can lead to the semi-legal leasing of land. Taking these parameters into account, farm water demands fluctuate yearly, especially for farms containing unplanted areas and for the farms without fruit trees. The first results show that it is even more complex to assess water demand for cooperative farms, within which land leasing occurs. Furthermore, the area of land attributed to tenants can vary from year to year. Often negotiations over water usage and access rights between farmers are required within the same cooperative farm. Coefficients related to the surveyed farmer behaviours, which refer to the watering time and times at which irrigation was stopped, were integrated into the individual water demand equation.