26 research outputs found
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 The paper concludes that knowing how much is withdrawn, where, and by whom provides helpful information for more informed groundwater management by a better understanding of the response of users to declining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
AccÚs à l'eau souterraine et différenciation des exploitations agricoles dans le Bas Cheliff (Algérie) .
International audienc
Le rÎle 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.LâaccĂšs des jeunes agriculteurs aux ressources fonciĂšres est peu pris en compte dans les dĂ©bats sur la durabilitĂ© des agricultures dans les pays du Sud. Les dispositifs de transfert foncier vers cette catĂ©gorie sociale, importante sur le plan dĂ©mographique, restent rares et peu opĂ©rants. Nous montrons ici, Ă travers lâĂ©tude de trois situations irriguĂ©es en Tunisie, que des transferts de terres vers les jeunes existent mais quâils sâeffectuent souvent de maniĂšre informelle et plus Ă travers diffĂ©rentes formes de faire-valoir indirect (FVI) quâĂ travers un transfert de propriĂ©tĂ©. Nous analysons le rĂŽle jouĂ© par le faire-valoir indirect dans la flexibilitĂ© des systĂšmes fonciers locaux et nous discutons le caractĂšre durable des dynamiques qui en dĂ©coulent. Nous discutons enfin le dĂ©fi majeur que reprĂ©sente pour les dĂ©cideurs politiques en Tunisie et au Maghreb, lâinscription de cette agriculture informelle dans une perspective durable. Approfondir les connaissances sur le rĂŽle jouĂ© par le FVI dans la flexibilitĂ© des systĂšmes fonciers et agraires locaux, peut fournir des pistes de rĂ©flexions pour mieux valoriser des ressources en terre et en eau trĂšs disputĂ©es en Tunisie, et ailleurs au Maghreb
Endoscopic ultrasonographic characterization of peridigestive lymph nodes: parametric images and quantitive analysis
Objectifs. La prĂ©cision diagnostique de l'Ă©choendoscopie dans le bilan d'extension ganglionnaire des cancers digestifs pourrait ĂȘtre amĂ©liorĂ©e par l'analyse paramĂ©trique de la texture des images. Nous avons cherchĂ© Ă Ă©valuer les rĂ©sultats de cette mĂ©thode dans une Ă©tude prospective. MĂ©thodes. Cent cinq ganglions pĂ©ri-digestifs ont Ă©tĂ© analysĂ©s chez 80 malades. Le diagnostic final Ă©tait obtenu par l'histologie de la piĂšce opĂ©ratoire ou par le suivi des patients. Il s'agissait de 41 ganglions inflammatoires bĂ©nins et de 64 ganglions mĂ©tastatiques. Les images Ă©taient obtenues durant une Ă©choendoscopie conventionnelle, numĂ©risĂ©es puis transfĂ©rĂ©es sur une station de travail pour l'analyse paramĂ©trique. Deux rĂ©gions d'intĂ©rĂȘt (RI) Ă©taient sĂ©lectionnĂ©es pour chaque ganglion (ganglion entier et portion pĂ©riphĂ©rique). 21 paramĂštres Ă©taient Ă©tudiĂ©s pour chaque RI (2 paramĂštres de 1er ordre et 19 de second ordre). Les paramĂštres Ă©taient Ă©tudiĂ©s par analyse uni- puis multivariĂ©e pour dĂ©finir les paramĂštres discriminant les ganglions inflammatoires des ganglions mĂ©tastatiques. Principaux rĂ©sultats. Sept paramĂštres, tous de second ordre, pouvaient distinguer les ganglions inflammatoires et mĂ©tastatiques de façon indĂ©pendante. La sensibilitĂ© de l'interprĂ©tation par l'endoscopiste (qui possĂ©dait les informations cliniques et morphologiques pertinentes) Ă©tait de 83 % et la spĂ©cificitĂ© de 90 %. La sensibilitĂ© et la spĂ©cificitĂ© de l'analyse de texture Ă©taient de 56 % et 60 %, respectivement. Conclusions. Ces rĂ©sultats suggĂšrent que l'analyse paramĂ©trique de la texture des images ganglionnaires d'Ă©choendoscopie n'amĂ©liore pas les performances de l'interprĂ©tation visuelle d'un opĂ©rateur entraĂźnĂ© disposant des Ă©lĂ©ments 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 Ă 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 Ă 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
O papel fundamental dos agentes da cadeia de abastecimento no desenvolvimento da irrigação por ĂĄguas subterrĂąneas no norte da Ăfrica
Impact of medication review via tele-expertise on unplanned hospitalizations at 3âmonths of nursing homes patients (TEM-EHPAD): study protocol for a randomized controlled trial
International audienc