Specifying the differentiated contribution of farmers to groundwater depletion in two irrigated areas in North Africa

International audienceMuch attention has been paid to the issue of groundwater depletion linked to intensive groundwater-based agriculture in (semi-)arid areas. Often referred to as the 'overexploitation' of aquifers, groundwater depletion is generally attributed to the entire agricultural sector without distinguishing between different uses and users. Although it expresses a general concern for future users, the ambiguous term of 'overexploitation' does not acknowledge the contested nature of groundwater use and emerging inequalities. Also, the impact of inequality on groundwater depletion is rarely questioned. The aim of this article is to investigate how and by whom groundwater is depleted, and in turn, how unequal access to groundwater fuels the socioeconomic differentiation of farms and groundwater depletion. Based on a detailed analysis of groundwater use from a user perspective in two irrigated areas in North Africa (Morocco and Algeria), this study shows how the context of groundwater depletion exacerbates'and is exacerbated by'existing inequalities. The paper concludes that knowing how much is withdrawn, where, and by whom provides helpful information for more informed groundwater management by a better understanding of the response of users to declining groundwater conditions and the interests and incentives of different social categories of famers to contribute to groundwater management

Topical collection groundwater-based agriculture in the Mediterranean

Groundwater resources in semi-arid areas and especially in the Mediterranean face a growing demand for irrigated agriculture and, to a lesser extent, for domestic uses. Consequently, groundwater reserves are affected and water-table drops are widely observed. This leads to strong constraints on groundwater access for farmers, while managers worry about the future evolution of the water resources. A common problem for building proper groundwater management plans is the difficulty in assessing individual groundwater withdrawals at regional scale. Predicting future trends of these groundwater withdrawals is even more challenging. The basic question is how to assess the water budget variables and their evolution when they are deeply linked to human activities, themselves driven by countless factors (access to natural resources, public policies, market, etc.). This study provides some possible answers by focusing on the assessment of groundwater withdrawals for irrigated agriculture at three sites in North Africa (Morocco, Tunisia and Algeria). Efforts were made to understand the different features that influence irrigation practices, and an adaptive user-oriented methodology was used to monitor groundwater withdrawals. For each site, different key factors affecting the regional groundwater abstraction and its past evolution were identified by involving farmers' knowledge. Factors such as farmer access to land and groundwater or development of public infrastructures (electrical distribution network) are crucial to decode the results of well inventories and assess the regional groundwater abstraction and its future trend. This leads one to look with caution at the number of wells cited in the literature, which could be oversimplified

Accès à l'eau souterraine et différenciation des exploitations agricoles dans le Bas Cheliff (Algérie) .

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Le rôle du faire-valoir indirect dans le renouvellement générationnel des agriculteurs irrigants en Tunisie

National audienceAccess to land for the young generation of farmers is hardly taken into account in the debates concerning the agriculture sustainability of agriculture in the Southern countries. In these countries, where the population is often very young, the procedures for the transfer of agricultural assets are frequently absent and generally ineffective when they exist. We show in this article through the case study of three irrigated situations in Tunisia, that measures to transfer lands to a young generation of farmers operate informally through indirect farming. We analyze the role of indirect farming in creating flexibility in local land use systems and discuss the sustainability of the resulting dynamics. We finally discuss finally the major challenge for the policy makers in Tunisia and in North Africa, to include informal agriculture in policy making to provide more sustainable perspectives. Better knowledge about the role of the indirect farming in providing flexibility to local land use and agrarian systems can provide ideas for a better use of land and water resources, which are disputed contested in Tunisia and elsewhere in North Africa.L’accès des jeunes agriculteurs aux ressources foncières est peu pris en compte dans les débats sur la durabilité des agricultures dans les pays du Sud. Les dispositifs de transfert foncier vers cette catégorie sociale, importante sur le plan démographique, restent rares et peu opérants. Nous montrons ici, à travers l’étude de trois situations irriguées en Tunisie, que des transferts de terres vers les jeunes existent mais qu’ils s’effectuent souvent de manière informelle et plus à travers différentes formes de faire-valoir indirect (FVI) qu’à travers un transfert de propriété. Nous analysons le rôle joué par le faire-valoir indirect dans la flexibilité des systèmes fonciers locaux et nous discutons le caractère durable des dynamiques qui en découlent. Nous discutons enfin le défi majeur que représente pour les décideurs politiques en Tunisie et au Maghreb, l’inscription de cette agriculture informelle dans une perspective durable. Approfondir les connaissances sur le rôle joué par le FVI dans la flexibilité des systèmes fonciers et agraires locaux, peut fournir des pistes de réflexions pour mieux valoriser des ressources en terre et en eau très disputées en Tunisie, et ailleurs au Maghreb

Endoscopic ultrasonographic characterization of peridigestive lymph nodes: parametric images and quantitive analysis

Objectifs. La précision diagnostique de l'échoendoscopie dans le bilan d'extension ganglionnaire des cancers digestifs pourrait être améliorée par l'analyse paramétrique de la texture des images. Nous avons cherché à évaluer les résultats de cette méthode dans une étude prospective. Méthodes. Cent cinq ganglions péri-digestifs ont été analysés chez 80 malades. Le diagnostic final était obtenu par l'histologie de la pièce opératoire ou par le suivi des patients. Il s'agissait de 41 ganglions inflammatoires bénins et de 64 ganglions métastatiques. Les images étaient obtenues durant une échoendoscopie conventionnelle, numérisées puis transférées sur une station de travail pour l'analyse paramétrique. Deux régions d'intérêt (RI) étaient sélectionnées pour chaque ganglion (ganglion entier et portion périphérique). 21 paramètres étaient étudiés pour chaque RI (2 paramètres de 1er ordre et 19 de second ordre). Les paramètres étaient étudiés par analyse uni- puis multivariée pour définir les paramètres discriminant les ganglions inflammatoires des ganglions métastatiques. Principaux résultats. Sept paramètres, tous de second ordre, pouvaient distinguer les ganglions inflammatoires et métastatiques de façon indépendante. La sensibilité de l'interprétation par l'endoscopiste (qui possédait les informations cliniques et morphologiques pertinentes) était de 83 % et la spécificité de 90 %. La sensibilité et la spécificité de l'analyse de texture étaient de 56 % et 60 %, respectivement. Conclusions. Ces résultats suggèrent que l'analyse paramétrique de la texture des images ganglionnaires d'échoendoscopie n'améliore pas les performances de l'interprétation visuelle d'un opérateur entraîné disposant des éléments habituels du dossier clinique

Three-dimensional measurement of Mg dopant distribution and electrical activity in GaN by correlative atom probe tomography and off-axis electron holography

The distribution and electrical activity of p-type doping (Mg) in gallium nitride (GaN) grown by metal organic chemical vapor deposition was investigated by correlating atom probe tomography (APT) and off-axis electron holography. APT results revealed that high Mg concentrations promote the formation of Mg-rich clusters. This is associated with the formation of pyramidal inversion domains (PIDs). The direct measurement of the doping concentration outside the clusters provided by APT suggests a saturation in the p-type electrical activity for Mg concentrations above 7 × 1019 cm-3. Maps of the electrostatic potential provided by off-axis electron holography confirm that the highest carrier concentration was achieved in the regions with the highest dopant concentration of 2 × 1020 cm-3, despite the presence of a high density of Mg-rich clusters revealed by APT. The correlation of these techniques suggests that PIDs are not the major cause of the reduction in electrostatic potential

De l'archipel oasien à l'eldorado pionnier au Sahara Algérien

International audienceSince the 1980s, the Biskra region in Algeria's Sahara has undergone rapid agricultural change leading to territorial transformation. Horticultural production under greenhouses, associated with a rapid expansion of date palm plantations, has led to a tangible agricultural boom that is constantly pushing the boundaries of agricultural production and constitutes a true pioneering fringe. To understand the pioneering logics at work, we propose to study the pioneer fringe through three fronts, namely land, water and infrastructure. First, we analyse each front separately in order to understand its logic. In a second step, through three illustrations, we show how these fronts interpenetrate, accelerate one another or, on the contrary, constrain the pioneer fringe. The analysis of the advance of the pioneering fringe has shown that it results from the interweaving of the three main fronts and each of these combines both the actions of the state and private initiative

Impact of medication review via tele-expertise on unplanned hospitalizations at 3 months of nursing homes patients (TEM-EHPAD): study protocol for a randomized controlled trial

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