Analyse du réseau piézométrique national tunisien

L’observation régulière du niveau des eaux souterraines a débuté en Tunisie il y a plus de soixante ans. Depuis, le réseau piézométrique national, composé aujourd’hui de près de 3 700 points de surveillance (puits, forages et piézomètres), permet l’observation de 148 systèmes aquifères et comporte des séries de mesures parfois longues d’une cinquantaine d’années. Pour caractériser le réseau piézométrique national, deux types d’indicateurs sont définis : a) des indicateurs portant sur la qualité intrinsèque des réseaux existants; b) des indicateurs décrivant le besoin d’informations complémentaires et la nécessité de consolidation des réseaux. Les indicateurs de qualité sont liés à la densité spatiale, la durée de surveillance, le fonctionnement, la couverture du réseau par des piézomètres, le contrôle de l’exploitation et l’évolution temporelle du réseau. Les indicateurs de consolidation des réseaux sont relatifs à la variabilité piézométrique, au taux d’exploitation ou de surexploitation, aux ressources exploitables et aux superficies des systèmes aquifères. Se fondant sur ces indicateurs, la classification des systèmes aquifères surveillés met en évidence les nappes disposant de réseaux de meilleure qualité et celles nécessitant une consolidation de leur réseau. La synthèse globale des différents indicateurs a permis de dégager les systèmes aquifères nécessitant des actions prioritaires en matière de rationalisation des réseaux piézométriques. Les résultats obtenus au terme de cette analyse concordent bien avec la situation actuelle observée sur le terrain.The regular observation of groundwater levels began in Tunisia more than sixty years ago. The national groundwater level network consists presently of almost 3,700 monitoring points (wells, boreholes and piezometers), monitoring 148 aquifers with some long-term series of about fifty years. To characterize the national piezometric network, two types of indicators were defined: a) indicators connected with the intrinsic quality of the existing networks, and b) indicators describing the need for additional information for network consolidation. Quality indicators relate to space density, monitoring duration, functioning, spatial coverage of the network by piezometers, exploitation control and temporal evolution of the network. Consolidation indicators relate to piezometric variation, exploitation or overexploitation rates, resources and aquifer area. Based on these indicators, the classification highlights aquifers having the best quality networks and those requiring a network consolidation. The global synthesis highlights aquifers requiring priority actions in terms of rationalization of the piezometric network. The results obtained at the end of this analysis agree well with the present situation as observed in the field

CUTANEOUS MANIFESTATIONS OF PRIMARY IMMUNODEFICIENCY DISEASES IN TUNISIAN CHILDREN

Abstract. Skin manifestations are frequent among patients with primary immunodeficiency diseases (PIDs). Their prevalence varies according to the type of immunodeficiency. This review provides the reader with an up-to-date summary of the common dermatologic manifestations of PIDs among Tunisian children. We conducted a prospective study on two hundred and ninety children with immune deficiency. Demographic details (including age, sex, and consanguinity) with personal and family history were recorded. Special attention was paid to cutaneous manifestations. Dermatological involvements were grouped according to the etiology of their most prominent sign. Cutaneous manifestations were found in 164 patients (56.5%). They revealed the diagnosis of PIDs in 71 patients (24.5 %). The mean age at presentation was 21 months. Overall the most prominent cutaneous alterations were infectious. They accounted for 106 cases (36.55%). The most prevalent causes of cutaneous infections were bacterial: 93 cases (32.06%). Immuno-allergic skin diseases were among the common findings in our study. These include eczematous dermatitis found in 62 cases (21.38%). Malignancy related PIDs was seen in a boy with Wiskott Aldrich syndrome. He developed Kaposi’s sarcoma at the age of 14 months. Cutaneous changes are common among children with PIDs. In pediatric patients with failure to thrive, chronic refractory systemic manifestations often present in other family members, recurrent cutaneous infections unresponsive to adequate therapy, atypical forms of eczematous dermatitis or unusual features should arouse the suspicion of PIDs and prompt specialized immunologic consultation should be made

Rapport IV.6. Évolution à long terme de la qualité des eaux souterraines dans un bassin hydrogéologique, provoquée par l’activité humaine

In large sedimentary basins with multilayered aquifers, the total dissolved salts content of the water of each layer varies with depth, and with the mecanism of recharge. Modifications of the natural conditions, due to pumping, may, in the long run, change this salt content of groundwater. In arid zones, also, the high evaporation rates may lead to a rapid salt buid-up of the water-table aquifer, and a progressive contamination of the deeper aquifers. A digital model is given which offers an approximate solution of the transport equations in multilayered aquifers, and which is applied to a case study.Dans les aquifères sédimentaires multicouches, la salinité des eaux des différents horizons varie en fonction de leur profondeur et de leur condition d’alimentation. Les perturbations apportées aux équilibres naturels par les exploitations peuvent modifier à long terme cette salinité des eaux souterraines. En pays aride enfin, les fortes évaporations peuvent conduire à une rapide salinisation des nappes phréatiques et à une contamination progressive des nappes profondes. Un modèle mathématique de résolution approchée des équations du transport en aquifères multicouches est présenté, avec une application à un problème réel.Besbes Mustapha, Ledoux Emmanuel, Levassor A., Marsily Ghislain de. Rapport IV.6. Évolution à long terme de la qualité des eaux souterraines dans un bassin hydrogéologique, provoquée par l’activité humaine. In: La mécanique des fluides et l'environnement. Prévision et maîtrise de la qualité de l'eau et de l'air. Compte rendu des quatorzièmes journées de l'hydraulique. Paris, 7-9 septembre 1976. Tome 2, 1977

Benzene ring containing cationic gemini surfactants: Synthesis, surface properties and antibacterial activity

International audienceNew quaternary ammonium gemini surfactants of the general formula CnH2n+1-Ph-NHCOCH2N+(CH3)(2)-(CH2)(s)- N+(CH3)(2)CH2CONH-Ph-CnH2n+1 (with n = 8, 10,12, 14,16 and s = 2,4, 6) have been synthesized by an efficient synthetic pathway based on the quaternization of N,N,N',N'-tetramethylalkylenediamine with 2-bromo-N-(4-(alkyloxy) phenyl) acetamides. Their surface properties were investigated by surface tension, electrical conductivity and dynamic light scattering (DLS) measurements. The study shows that the incorporation of a benzene ring in the hydrophobic tail prompts micelle formation which leads to a smaller cmc values in the range of 0.21-0.009 mM compared to analogous geminis bearing alkyl hydrophobic chains. The length of the spacer and the hydrophobic chain has a pronounced effect on the aggregation behavior of surfactants molecules. This was confirmed by the average surfaces occupied by these molecules at the water-air interface calculated from the Gibbs equation. The size of the aggregates was measured by employing dynamic light scattering technique. The antimicrobial activity of investigated surfactants was evaluated against three microorganisms: Staphylococcus aureus, Escherichia coli and Candida albicans. (C) 2017 Elsevier B.V. All rights reserved

Hydrological stochastic modelling of a basin affected by land-use changes: case of the Merguelill basin in central Tunisia

International audienceSeveral works in the area of water and soil conservation (WWSC) have been implemented in the Merguellil basin. In order to test their efficiency, an impact study of these works was carried out by hydrological modelling. The MODCOU model, which simulates both surface and underground flow at the same time, was used. The WWSC were considered through a parameterization of the production function. The calibration of the model was carried out with a multi-objective stochastic approach on several observation sites. The results show that the actual evapotranspiration is the largest component of the surface system. The groundwater system is largely overdrawn with outputs estimated to be four times higher than the inputs. This study has shown the improvement in model representativeness by assigning specific parameters to the production functions of the WWSC zone