Simulated annual values were in general more accurate than simulated monthly values. 13 APEX predicted that improving irrigation management (change of irrigation system 14 and/or scheduling) will decrease N loads in IRF over current values by 45% (Akarsu), 15 40% (La Violada), and 8% (Sidi Rached). However, improved N fertilization only will 16 reduce N loads in IRF by 17% (Akarsu) or below 5% (La Violada and Sidi Rached). 17Improving irrigation management will increase IRF NO 3 -N concentrations by 19% in La 18 Violada and will decrease or will remain the same in the other two watersheds. APEX 19 simulations identified the main soils (shallow and low water holding capacity soils) and 20 crops (heavily fertilized or shallow-root crops) N polluters within the studied watersheds. 21Overall, APEX simulated that the improvement of irrigation performance was the best 22 management strategy to decrease off-site N pollution while maintaining or increasing crop 23 yields in the three studied Mediterranean watersheds. 24
Two contrasting views prevail on groundwater use in situations of predominantly state-led irrigation development. The first considers 'groundwater as liberation', i.e., how, by capturing the irrigation initiative, farmers liberated themselves from 'state' water, enabling more intensive and productive agriculture. The second view -'groundwater as anarchy' -considers groundwater as a M. Kuper (*) Cirad,
In the irrigated scheme of West Mitidja, access to land and water is ensured through countless local informal arrangements. The assignees of small collective farms have subdivided the land informally, and rent out part of it to lessees, thereby circumventing current legislation. The surface irrigation system provides only a small proportion of irrigation water to farmers, who rely mainly on groundwater for irrigation. The results of our analyses show that the agricultural dynamics of this perimeter are to a large extent ensured by ''invisible'' farmers cultivating land obtained through informal land markets and using groundwater via ''illicit'' tubewells. These farmers are also important vectors for innovation (new irrigated cropping systems, drip irrigation). We organized a series of workshops with farmers (assignees and lessees) and government agencies to explore agricultural development and water management perspectives in the area. Our work showed that it is land and water markets that should be formalized rather than land or water property so that lessees will be considered as actors for water management and agricultural development in the area.
In many countries, farmers are turning to groundwater to make up for surface water scarcity and to deal with increasing water demand, even inside large-scale irrigation schemes. In many situations, this leads to the mining of groundwater resources, which in turn threatens the sustainability of the farms that depend on this resource. The purpose of this study was to find ways to provide the necessary information to stakeholders to enable them to construct rules for sustainable groundwater management. The dynamics of water resources and water use practices were analysed and management indicators were designed for two irrigation schemes in North Africa: Tadla (Morocco) and Mitidja West (Algeria). The results showed, firstly, that available groundwater has decreased; secondly, that farming systems depend to an increasing extent on groundwater resources, and thirdly, that individual and collective access to groundwater depends on informal arrangements. We developed and tested a platform for dialogue for water management focused on exploring plausible scenarios of agricultural development in relation to the use of groundwater. Copyright # 2009 John Wiley & Sons, Ltd.
RÉ SUMÉDans beaucoup de régions irriguées du monde, traditionnellement alimentées par des eaux de surface, le recours aux nappes souterraines est de plus en plus important suite à des pénuries d'eau de surface et à l'augmentation de la demande en eau. Cela induit une surexploitation de ces ressources menaçant en conséquence la durabilité des exploitations agricoles. L'objectif de l'étude est de développer des méthodes pour produire de l'information pour les acteurs et les utilisateurs des nappes pour leur permettre d'élaborer des règles de gestion. La dynamique des nappes et les pratiques des irrigants ont été analysées dans deux périmètres irrigués: Tadla (Maroc) et Mitidja Ouest (Algérie). Les résultats montrent que (1) la disponibilité en eau souterraine est en diminution, (2) les systèmes de production dépendent fortement des nappes, et (3) Vers une nouvelle approche de la gestion des ressources en eau souterraine: transformer l'information pour construire des regles de gestion.
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