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Charismatiques et visionnaires, des leaders nous marquent souvent en raison de leur personnalite flamboyante, de leur eloquence et de leur assurance. Faut-il alors s’etonner que plusieurs gestionnaires soient reticents a se comporter avec humilite ? Et pourtant, une majorite d’employes apprecient les dirigeants qui osent en faire preuve.

The Barthelasse alluvial aquifer has been used for decades to supply water to 180,000 inhabitants. The pumping field is located around 200 m from the Rhône river which makes it particularly vulnerable to any pollution from the Rhône. Between the Rhône and the pumping field is a Girardon unit whose role is to stabilise the banks and to facilitate river navigation. A fortnightly monitoring over a full hydrological year as well as hourly sampling during a flood event in winter 2019 were carried out to study the transfer processes between the Rhône and the pumping field. Samples were collected in the Girardon unit and in the pumping field.The Rhône showed cyclicality in its isotopic signature with enrichment in heavy isotopes during the winter period, particularly during floods and a depletion during the summer period. This variation was also found within the alluvial aquifer. The application of LPMs models showed that the average transfer time between the Rhône and the Girardon unit was 20 days and 50 days between the Rhône and the Barthelasse pumping field. For the Girardon unit, this result was confirmed using a high frequency monitoring of electric conductivity.This study highlighted the importance of using a sampling strategy including several frequencies to consider the diversity of hydrological situations. For the Rhône, event-based monitoring proved relevant to account for isotopic variability throughout the year. Models calibration procedure was also discussed. In LPM models, the RMSE criterion is the most commonly used. It is recommended to use standardised criteria instead and to adapt the choice of the criterion to the observed isotopic variability. This work also highlighted the impact of the disruption of hydraulic exchanges between the river and the water table caused by the presence of the Girardon unit in terms of the propagation of contaminants.

Fluorine is known to be a key element for various components of batteries since current electrolytes rely on Li-ion salts having fluorinated ions and electrode binders are mainly based on fluorinated polymers. Metal fluorides or mixed anion metal fluorides (mainly oxyfluorides) have also gained a substantial interest as active materials for the electrode redox reactions. In this review, metal fluorides for cathodes are considered; they are listed according to the dimensionality of the metal fluoride subnetwork. The synthesis conditions and the crystal structures are described; the electrochemical properties are briefly indicated, and the nature of the electron transport agent is noted. We stress the crucial importance of the elaboration processes to induce the presence of cation disorders, of anion substitutions (mainly F

Groundwater extracted from the Barthelasse Island aquifer, surrounded by the river Rhone (southeastern France), contributes to the drinking water supplies of 180,000 inhabitants. Owing to its location close to the river and the presence of two backwaters (oxbow lakes), the pumped groundwater is highly vulnerable to river pollution. A pumping test was conducted over 24 h to analyse and quantify the water exchange processes between the river, backwaters and groundwater. During the pumping test, isotopic (δ18O, δ2H and 222Rn), hydrochemical and hydrophysical monitoring of the groundwater was undertaken. Hydraulic heads were measured in pumping wells and at a piezometer located between the wells. Discrete water samples were collected at several observation points in the field, including the backwater and river. The results show mixing between three end-members, as defined by the deuterium excess and silica concentration, led by river Rhone water which had been affected by water–rock interactions over time and mixing with surface evaporated waters. The pumped water resulted from mixing between three end-members, all of which depended on the river Rhone but differed in terms of residence time in the system. Although the groundwater pumping wells are close to each other (

High‐elevation mountains often constitute for basins important groundwater recharge sources through mountain‐front recharge processes. These processes include streamflow losses and subsurface inflow from the mountain block. However, another key recharge process is from irrigation practices, where mountain streamflow is distributed across the irrigated piedmont. In this study, coupled groundwater fluctuation measurements and environmental tracers (¹⁸O, ²H, and major ions) were used to identify and compare the natural mountain‐front recharge to the anthropogenically induced irrigation recharge. Within the High Atlas mountain front of the Ourika Basin, Central Morocco, the groundwater fluctuation mapping from the dry to wet season showed that recharge beneath the irrigated area was higher than the recharge along the streambed. Irrigation practices in the region divert more than 65% of the stream water, thereby reducing the potential for in‐stream groundwater recharge. In addition, the irrigation areas close to the mountain front had greater water table increases (up to 3.5 m) compared with the downstream irrigation areas (

Cet article examine le petitionnement en ligne a partir de l’analyse des donnees du site lapetition.be, soit plus de 12 000 petitions ayant recolte 3,25 millions de signatures. L’heterogeneite textuelle des donnees collectees (inscrites par les internautes et generees par le dispositif) a ete apprehendee a la fois comme traces des contraintes du dispositif et de ses modalites d’appropriation, et egalement comme caracteristiques de l’acte de petitionnement et de sa pluralite. L’analyse des textes d’appels des petitions fait apparaitre leurs traits saillants (formes d’adresse, lexique, enonciation) au regard des rubriques et du nombre de signatures. L’analyse des commentaires met au jour la diversite des raisons qui conduisent a signer une petition et eclaire la pluralite de l’acte de petitionnement.

La pandémie de COVID-19 bouleverse l’industrie du tourisme et risque de se faire sentir pendant encore plusieurs mois, voire des années. Il faudra ensuite s’en remettre le plus rapidement possible, mais encore faudra-t-il que les voyageurs soient au rendez-vous en grand nombre. Cet article présente les résultats d’une consultation auprès de voyageurs (n=1084) en début de confinement au Canada. Il semble que les voyages à proximité du domicile seront favorisés et que les voyages récréatifs ne reprendront que lorsque les conditions seront propices et que les tarifs seront concurrentiels. La littérature sur les désastres et les crises sanitaires démontre qu’il est primordial de rassurer les voyageurs quant à l’autorisation du gouvernement de voyager en toute sécurité avant même d’amorcer des campagnes publicitaires pour encourager le voyage à l’étranger. Les analyses permettent de constater que les voyageurs fréquents et les millénariaux sont les plus susceptibles de reprendre leurs habitudes de voyage., The COVID-19 pandemic is disrupting the tourist industry and its impact could be felt for many more months, if not years. Tourism will need to recover as fast as possible, but for that to happen, travellers will have to be there in great numbers. This article presents the results of a survey among travellers (n=1,084) at the start of the confinement in Canada. It seems that close-to-home trips will be favoured and that recreational trips will only resume when conditions will be conducive and rates competitive. Literature on disasters and health crises shows that it is crucial to reassure travellers as to the government’s authorization for safe travel before launching advertising campaigns to encourage travelling abroad. Based on the results of the analyses, frequent travellers and millennials are those more likely to return to their travelling habits.

International audience; In this work, the synthesis of β-AlF3–x(OH)x nanoparticles with very high specific surface area (SSA) using a microwave-assisted solvothermal process is reported. The influence of synthesis parameters on the morphology and SSA was investigated, and the nature of the solvent is shown to have the greatest impact. Five samples prepared using different solvent mixtures were deeply characterized by thermogravimetric analysis (TGA), N2 sorption, powder X-ray diffraction, transmission electron microscopy (TEM), and 19F and 27Al high-field solid-state NMR. Their SSAs range from 25 to 345 m2·g–1 with an associated OH content slightly increasing from ≈16% (AlF2.52(OH)0.48) to ≈19% (AlF2.42(OH)0.58), as estimated by TGA and 27Al high-field solid-state NMR. Compared to previous reference work [Dambournet, D., Chem. Mater. 2008, 204 1459−1469], β-AlF3–x(OH)x nanoparticles with SSAs up to 4 times larger were obtained. TEM revealed the formation of hollow nanostructures except when the surface exceeds 300 m2·g–1, in which case isolated nanoparticles are observed. The sample with the highest SSA also displaying an appealing cumulative pore volume of 0.060 cm3·g–1, its hydrogen adsorption capability was evaluated to show that β-AlF3–x(OH)x nanoparticles have a potential interest for hydrogen storage applications.

The Barthelasse alluvial aquifer is used to supply water to 180,000 inhabitants. The pumping field is located less than 200 m from the Rhône and is 100% fed by water from the Rhône, which makes it particularly vulnerable to any pollution from the Rhône. Between the Rhône and the pumping field is a Girardon unit, an arrangement that can be found regularly along the banks of the lower and middle reaches of the Rhône, and whose role is to stabilise the banks (alluvial deposits) and to facilitate river navigation. In order to know the transfer times between the Rhône and the pumping field, fortnightly monitoring was carried out over a hydrological year, as well as hourly monitoring during a flood in the winter of 2019. The Rhône shows a cyclicality in its isotopic signature with enrichment in heavy isotopes during the winter period, particularly during floods, and a depletion during the summer period. This variation is found well within the associated alluvial aquifer. The application of LPMs models showed that the average transfer time between the Rhône and the Girardon unit was 20 days and 50 days between the Rhône and the Barthelasse pumping. This study highlighted the importance of using several sampling frequencies to consider the diversity of hydrological situations. For the Rhône, event-based monitoring (flooding) proved to be relevant to account for isotopic variability throughout the year. This work also highlighted the impact of the disruption of hydraulic exchanges between the river and the water table caused by the presence of the Girardon unit in terms of the propagation of contaminants.

International audience; A novel two-step strategy to prepare amorphous oxyfluorides, containing both divalent and trivalent 3d-metals, as cathode materials for lithium batteries is presented. The first step involves the preparation of hydrated fluorides M2+M3+2F8(H2O)2 (M2+ = Mn, Fe, Co, Ni, Cu; M3+ = V, Fe) by microwave-assisted solvothermal synthesis. Besides the MnFe2F8(H2O)2 and CuFe2F8(H2O)2 phases, three new compounds, Fe1.3V1.7F8(H2O)2, CoFe2 F8(H2O)2, and Ni- Fe2F8(H2O)2, which are isostructural with Fe3F8(H2O)2, have been unraveled. The second step consists in the decomposition of M2+M3+2F8(H2O)2 into amorphous oxyfluorides M2+M3+2F8−2xOx via suitable thermal treatments.. The amorphous materials show a greater electrochemical activity toward Li than their parent phases, among them being CuFe2F6O, which displays the best performance as a cathode material with a first discharge capacity of 310 mAh·g−1. We show that such a large capacity results from cumulative insertion and displacement reactions.

Distributed integrated hydrological models (IHMs) are the most effective tools for estimating groundwater recharge in arid and semi-arid areas characterized by thick unsaturated zone. It is also important to capture spatio-temporal aquifer dynamics by using real-time or near-real-time data, for sustainable water resources management. However, such data is often unavailable in developing countries where monitoring networks are scarce. In recent years, remote sensing has played an important role in providing spatio-temporal information for evaluation and management of water resources. Nevertheless, application of remote sensing in groundwater studies is still limited and has mainly focused on assessment of groundwater recharge and groundwater storage as well as to provide boundary conditions and driving forces for both standalone groundwater models and IHMs. This study entails application of remote sensing data in developing the distributed integrated hydrological model for Stampriet transboundary multi-layered aquifer system shared between Namibia, Botswana and South Africa. A numerical model has been set – up using MODFLOW 6 coupled with the Unsaturated Zone Flow (UZF) Package where Climate Hazards Infrared Precipitation with stations (CHIRPS) rainfall data and Global Land Evaporation Amsterdam Model (GLEAM) potential evapotranspiration data were implemented as the model driving forces. Other input data used include digital elevation model, and land-use/landcover and also soil datasets to define unsaturated zone parameters. The model has been calibrated with groundwater level measurements as the state variables in transient conditions at daily time step for a period of 16 years. The model-simulated unsaturated zone and groundwater storage was compared to GRACE-derived sub-surface storage anomaly, further also used to constrain the model. The calibrated model provides spatio-temporal water flux dynamics as well as water balances and hence an understanding of the groundwater-resource dynamics and replenishment. This information is shown useful for proper management of the transboundary water resource as well as for policy making.

Piedmont areas are globally important hydrological systems as transitional zones between mountains (headwater basins) where water is produced and adjacent plains (basins floor) where water is consumed. In arid and semiarid areas, the water availability in piedmonts have made them adequate places for rural communities’ settlement and irrigation activities. The hydrochemical processes controlling groundwater chemistry in the piedmont areas might be influenced by the interaction with the mountain streamflow, the geology, the climate and the human activities. In this study we investigated the hydrochemistry of the groundwater in the piedmont of Ourika wadi that is coming from the High-Atlas of Marrakech Mountains (central Morocco). The HCO3-Ca-Na groundwater type, inherited form the streamflow, is the primary water facies in the area. It has its origin from carbonates dissolution and silicates withering in the High-Atlas mountains. In the irrigated area, the ion exchange processes are responsible of Ca and Mg enrichment. Currently, the groundwater salinity is low and the chemical quality is excellent thanks to the seasonal groundwater recharge from the mountain streamflow and to the practiced traditional agriculture that generally uses high amounts of irrigation and low amounts chemical fertilizers. However, major concerns about groundwater sustainability arise from two parameters. Firstly, the snowmelt-driven runoff supplying the groundwater recharge in piedmonts is in continuous decrease because of the snow cover reduction observed in the last decades and forecasted in the future under climate change, likely putting more pressure on groundwater resources. Secondly, due to the growing anthropogenic activities the traditional agriculture might change to intensive agriculture using more chemicals and inducing pollution.

International audience; Metal fluorides with 3D open structures, pyrochlore (pyr) or hexagonal tungsten bronze (HTB), are promising materials as positive electrodes for rechargeable batteries or catalysts. Herein, we have developed a two-step synthesis procedure to obtain new anhydrous mixed-metal-cation fluorides crystallizing in the pyrochlore structure. The first step consists of preparing mixed-metal ammonium fluorides (NH4)M2+Fe3+F6 (M = Mn, Fe, Co Ni) using different synthesis strategies. For M = Mn, three allotropic varieties of (NH4)Mn2+Fe3+F6 are obtained; two phases adopt the expected pyrochlore network with either the cubic Fm3̅m or the orthorhombic Pnma space group, and the third phase exhibits a 3D network with narrow pseudotriangular cavities. 57Fe Mössbauer spectrometry indicates that the crystal structures are governed by the Fe3+/Mn2+ cationic order or disorder. The second step is a topotactic oxidation of pyr-(NH4)M2+Fe3+F6 under a molecular F2 flow. To better understand the reaction mechanism, the topotactic oxidation was followed by thermogravimetry, XRD, FTIR, and Mössbauer spectrometry. The successful synthesis of the first anhydrous pyr-M3+0.5Fe0.5F3 provides a new route to prepare anhydrous mixed-metal fluorides pyrochlore with empty cavities of the open framework.

International audience; Leptospirosis is a waterborne zoonosis (60,000 infections and 1 million deaths annually). Knowledge about the disease in the urban context is surprisingly rare, especially in Africa. Here, we provide the first study of leptospires in waters within an African city. A simple centrifugation-based method was developed to screen waterborne leptospires from remote or poorly areas. Major ions, trace elements, stable isotopes and pathogenic Leptospira were then seasonally investigated in 193 water samples from three neighborhoods of Cotonou (Benin) with different socio-environmental and hydrographic characteristics. Firstly, no leptospire was detected in tap waters. Secondly, although surface contamination cannot be excluded, one groundwater well was found leptospire positive. Thirdly, pathogenic Leptospira mainly contaminated surface waters of temporary and permanent ponds (9.5% and 27.3% of total prevalence, respectively). Isotopic signatures suggest that leptospires occurred in pond waters formed at the beginning of the rainy season following low to moderate rainfall events. Nevertheless, Leptospira-containing waters possess physico-chemical characteristics that are similar to the spectrum of waters sampled throughout the three sites, thus suggesting that Cotonou waters are widely compatible with Leptospira survival. The frequent contact with water exposes Cotonou inhabitants to the risk of leptospirosis which deserves more attention from public health authorities.

Mediterranean peatlands remain largely under-documented, except for detailed biological data such as fauna and flora taxa lists, and yet are increasingly threatened by water withdrawal and agriculture practices. This lack of information, particularly on their hydrogeological functioning, makes it impossible to evaluate their response to changing climate conditions. A pilot study on a representative Mediterranean peatland on the island of Corsica (France) was conducted to evaluate recharge modalities in the peatland using a coupled water-level monitoring, geochemical and isotope multi-tracing approach (electric conductivity, major ions, δ18O, δ2H, 3H, 87Sr/86Sr). The goal was to understand how water budgets in peatland ecosystems were maintained throughout the year, especially during the summer. Despite the remarkable stability of the peatland water level, the recharge contributions of varied water bodies through an alluvial aquifer vary significantly from one season to another. An end-member mixing analysis (EMMA) indicates that the peatland is mainly recharged by an alluvial aquifer. During fall-winter, the alluvial aquifer on which the peatland depends is recharged by the rainfall, a river, and shallow groundwater (colluvium). During spring-summer, water supply is provided mostly by a river, shallow, and deep groundwater (fractured granite). However, this specific hydrogeological functioning is not taken into account by environmental management policies making peatlands vulnerable to anthropogenic and climatic pressures. Thus, their actual status regarding water and aquatic environment management policies is discussed to provide recommendations for better consideration and preservation.

Hydrological models, with different levels of complexity, have become inherent tools in water resource management. Conceptual models with low input data requirements are preferred for streamflow modeling, particularly in poorly gauged watersheds. However, the inadequacy of model structures in the hydrologic regime of a given watershed can lead to uncertain parameter estimation. Therefore, an understanding of the model parameters&rsquo, behavior with respect to the dominant hydrologic responses is of high necessity. In this study, we aim to investigate the parameterization of the HBV (Hydrologiska Byr&aring, ns Vattenbalansavedelning) conceptual model and its influence on the model response in a semi-arid context. To this end, the capability of the model to simulate the daily streamflow was evaluated. Then, sensitivity and interdependency analyses were carried out to identify the most influential model parameters and emphasize how these parameters interact to fit the observed streamflow under contrasted hydroclimatic conditions. The results show that the HBV model can fairly reproduce the observed daily streamflow in the watershed of interest. However, the reliability of the model simulations varies from one year to another. The sensitivity analysis showed that each of the model parameters has a certain degree of influence on model behavior. The temperature correction factor (ETF) showed the lowest effect on the model response, while the sensitivity to the degree-day factor (DDF) highly depends on the availability of snow cover. Overall, the changes in hydroclimatic conditions were found to be mostly responsible for the annual variability of the optimal parameter values. Additionally, these changes seem to actuate the interdependency between the parameters of the soil moisture and the response routines, particularly Field Capacity (FC), the recession coefficient K0, the percolation coefficient (KPERC), and the upper reservoir threshold (UZL). The latter combines either to shrink the storage capacity of the model&rsquo, s reservoirs under extremely high peak flows or to enlarge them under overestimated water supply, mainly provoked by abundant snow cover.

International audience; Similar to many southern and southeast Asian regions, the mobilisation of arsenic (As) from sediments has driven a widespread contamination problem for groundwater resources in the Cambodian Mekong Delta. For the first time, the seasonal changes in As concentrations and potential links to groundwater pumping for irrigation in shallow aquifers of the Cambodian Mekong Delta are investigated. Using environmental tracers (δ18O, δ2H, 3H, major/trace ions and rare earth elements) the natural and pumping-induced changes in hydrogeological processes are identified. Three conceptual models are proposed: Model 1, where there is limited local recharge or low recharge rates (3H mean residence time > 60 years) and groundwater has a large range in As concentrations (0.2 to 393.8 μg/L). In this semi-confined aquifer, only one of the six groundwater sites has As concentrations that increase (by 10.9 μg/L) potentially due to groundwater pumping and resultant mixing with high-As and low (Pr/Sm)NASC groundwater. However, data on groundwater extraction volumes is required to verify the link with irrigation practices. Model 2, where groundwater is recharged by evaporated surface waters (fractionated δ18O and δ2H). There are moderate As concentrations (64.1–106.1 μg/L) but no significant seasonal changes even though the recharging waters have relatively greater organic carbon contents during the dry season (reduced Ce/Ce*anomaly). Finally model 3, where groundwater is significantly recharged by wet season rainfall (~50% from δ18O data). There is a minor increase in As concentrations with recharge (by 6. μg/L). These combined results highlight an aquifer system in the irrigated region of the Cambodian Mekong Delta where As concentrations are largely impacted by natural rather than irrigation processes. Seasonal-scale recharge processes control As processes where the aquifer is not confined by shallow clay layers, and where the aquifer is semi-confined As concentrations largely reflect longer-term natural processes.

In this work, we try to show that the contribution of a chatbot in an e-learning platform can bring more efficiency in learning. The observation being that many learners either abandon their learning. They judge that it’s not very effective, because often their questions are not answered adequately. Our emotional chatbot proposal shows that if we take into account the emotional state of the learner, we can offer him an answer adapted to his concerns that appear during their learning processes

International audience; In our search for novel insertion compounds for Li-based batteries, we have identified a new mixed iron vanadium based Hexagonal Tungsten Bronze (HTB) type phase. Its synthesis involves two steps which consist first of preparing mixed metal hydrated fluoride Fe1.64V1.36F8(H2O)2 by a microwave assisted thermal process, followed by thermal treatment under air to obtain metastable HTB–(Fe0.55V0.45)F2.67(OH)0.33 hydroxyfluoride. 57Fe Mössbauer spectrometry demonstrates the presence of oxidation states Fe2+ and Fe3+ in Fe1.64V1.36F8(H2O)2 as opposed to only Fe3+ in HTB–(Fe0.55V0.47)F2.67(OH)0.33. Moreover, the Mössbauer spectra recorded at 77 K reveal that none of the compounds shows magnetic ordering owing to the presence of V3+ distributed over the crystallographic sites of Fe3+. Complementary X-ray spectroscopy and Rietveld refinement further confirm the successful synthesis of HTB–(Fe0.55V0.45)F2.67(OH)0.33. Electrochemically, the new HTB–(Fe0.55V0.45)F2.67(OH)0.33 shows a first discharge capacity of 181 mA h g−1 with 67% of this capacity remaining upon cycling. Unlike HTB–FeF2.66(OH)0.34, the structure remains stable after the first discharge confirming the positive effect of vanadium in the HTB network.

In our search for novel insertion compounds for Li-based batteries, we have identified a new mixed iron vanadium based Hexagonal Tungsten Bronze (HTB) type phase. Its synthesis involves two steps which consist first of preparing mixed metal hydrated fluoride Fe1.64V1.36F8(H2O)2 by a microwave assisted thermal process, followed by thermal treatment under air to obtain metastable HTB-(Fe0.55V0.45)F2.67(OH)0.33 hydroxyfluoride. 57Fe Mössbauer spectrometry demonstrates the presence of oxidation states Fe2+ and Fe3+ in Fe1.64V1.36F8(H2O)2 as opposed to only Fe3+ in HTB-(Fe0.55V0.47)F2.67(OH)0.33. Moreover, the Mössbauer spectra recorded at 77 K reveal that none of the compounds shows magnetic ordering owing to the presence of V3+ distributed over the crystallographic sites of Fe3+. Complementary X-ray spectroscopy and Rietveld refinement further confirm the successful synthesis of HTB-(Fe0.55V0.45)F2.67(OH)0.33. Electrochemically, the new HTB-(Fe0.55V0.45)F2.67(OH)0.33 shows a first discharge capacity of 181 mA h g-1 with 67% of this capacity remaining upon cycling. Unlike HTB-FeF2.66(OH)0.34, the structure remains stable after the first discharge confirming the positive effect of vanadium in the HTB network.

Mountain-fronts constitute important groundwater recharge areas in arid and semiarid regions. Mountain-front recharge processes are generally identified, in natural systems, as streamflow losses and subsurface inflow from the mountain block. However, another key recharge process is from irrigation practices; where mountain streamflow is distributed across the irrigated piedmont. In this study, coupled groundwater fluctuation measurements and stable isotopes (18O and 2H) were used to identify and compare the natural mountain-front recharge to the anthropogenically-induced irrigation recharge. Within the High-Atlas mountain front of the Ourika basin, Tensift, Central Morocco, the groundwater fluctuation mapping from the dry to wet season showed that recharge from irrigation waters was higher than the recharge along the streambed. Irrigation practices in the region divert more than 65% of the stream water, thereby reducing the potential for stream recharge. Due to the traditional irrigation practices, upstream crops are preferentially irrigated with stream water over downstream areas. In downstream areas irrigation is only via stream water during large flood events and is otherwise supplemented by groundwater resources. These changes in water resources used for irrigation practices between upstream and downstream areas are reflected in the spatio-temporal evolution of the stable isotopes of groundwater. In the upstream irrigation area, the groundwater stable isotope values (d18O: -8.4 ‰ to -7.4 ‰) reflect recharge by the diverted stream water. In the downstream irrigation area, the groundwater isotope values are lower (d18O: -8.1 ‰ to -8.4 ‰) due to recharge with floods.The results from this study particularly highlight that irrigation can deeply modify both the recharge processes and the water balance in the mountain front areas. Groundwater resources in such areas become reliant on the irrigation practices as an important source of recharge, and this anthropogenic modification of the hydrological cycle should be assessed and taken into consideration within climate change impacts and integrated water management strategies.

Groundwater is the main water resource in arid and semi-arid areas. Its evaluation in terms of recharge, discharge, flow system and change in storage is thus vital for management purposes. However, distributed numerical models which are considered as favourable tools for assessment of groundwater resources are often limited by availability of input data especially in arid and semi-arid areas in developing countries where monitoring networks are scarce. Moreover, in case of transboundary aquifers, political, institutional, cultural, socio-economic differences among countries make management of groundwater even more complex.Remote sensing is a handy tool for monitoring water resources in data scarce areas. This study entails application of remote sensing data in developing a distributed integrated hydrological model for Stampriet Transboundary Aquifer System using MODFLOW-NWT coupled with the Unsaturated Zone Flow (UZF1) Package.Stampriet Transboundary Aquifer is a multi-layered aquifer system shared between Namibia, Botswana and South Africa. The aquifer system consists of three aquifers, characterized by low transmissivity and low storage, intercalated by two aquitards. Conceptually, the physical processes taking place in this system are reasonably understood in Namibia and not as much in Botswana and South Africa. However, quantification of water resources and fluxes is still limited.The aquifer system is mainly exploited in Namibia for socio-economic growth, where abstraction from storage has led to decline in local groundwater level. Water quality constraints have restrained its usage in South Africa, while in Botswana the potential for available resources is likely to be exploited, but there is not enough data for making firm decisions.A numerical model has been set – up in transient conditions at daily time step and calibrated with groundwater levels as the state variables and satellite rainfall and potential evapotranspiration as the model driving forces. The calibrated model provides spatio-temporal water flux dynamics as well as water balances and hence an understanding of the groundwater-resource dynamics and replenishment. The results are compared to analysis of GRACE data to further constrain the model. This information is useful for proper management of the transboundary water resource as well as for policy making.

International audience; Highlights• Predominant drivers of the unregulated shallow aquifer degradation in Cotonou were analysed using major ions, Cl/Br molar ratios and stables isotopes as environmental tracers. Vulnerability of this unofficial groundwater resource is due to either salinization or sewage leakage, which is temporally and spatially variable.• Increasing risks from sewage and septic tank leakage during the wet season in neighbourhoods located in discharge areas compared with increasing risk during the dry season in the recharge area.• Mixing with pond water and saline Lake Nokoué water highlight increased risks of shallow groundwater salinization during the dry and small wet seasons in discharge areas.AbstractIn Cotonou, as in many expanding West African cities, major population growth and infrastructural development has not kept up with informal settlement development onto floodable plains and marshes. The population of the slum, which makes up about 60% of the city's inhabitants, is highly disadvantaged and vulnerable to rising sea levels, flooding, sanitation and waste management issues. However, the risks associated with the use of contaminated shallow groundwater for domestic purposes are less recognised. Our study demonstrates that, in many instances, the cheaper option of the use of shallow groundwater from the coastal Quaternary aquifer for domestic purposes represents a significant risk for the poorer residents of Cotonou through the voluntary (drinking) or non-volontary (dish washing, cooking) consumption of this unmonitored and untreated water resource. In the 3 neighbourhoods surveyed, environmental tracers (major ions, Cl/Br molar ratios and stables isotopes) showed that this shallow aquifer is degraded by seawater intrusion as well as septic and sewerage contamination. In particular, the higher NOx concentrations correspond to ranges associated with sewerage and septic tank effluent pollution and the major ion concentrations and delta H-2-delta O-18 signatures showed that high salinity values are where groundwater mixes with saline Lake Nokoue water. The population using this resource from local wells should be made aware of seasonal changes in groundwater contamination and potential health risks associated with sewerage and septic tank contamination.

International audience; Crystals of two new 3D hybrid compounds, trans-Zn3TiF7(H2O)2(taz)3·3H2O and cis-Zn3TiF7(H2O)2(taz)3·C2H5OH, have been obtained by solvothermal synthesis ((taz)− = 1,2,4-triazolate C2H2N3 ligand). Their structures, determined from X-ray single crystal diffraction data in Cm and Pnma space groups, respectively, are based on Zn3N9(H2O)2F3 trimers linked by TiF6 octahedra that build trans- or cis-chains ∞[Zn3TiN9(H2O)2F7]. Water or ethanol in the structure cavities is released below 110 °C to give trans- or cis-Zn3TiF7(H2O)2(taz)3 and, on further heating, these intermediate phases dehydrate and lead to anhydrous trans- or cis-Zn3TiF7(taz)3. At 110 °C, the loss of ethanol concerns only ≈1/3 of the weight of cis-Zn3TiF7(H2O)2(taz)3·C2H5OH while the remaining part subsists up to 180 °C. This behaviour is attributed to a core–shell type configuration. Rehydration in humid air occurs at room temperature for the anhydrous cis-phase. All desolvated, dehydrated or rehydrated phase structures have been determined by X-ray powder diffraction and ab initio Rietveld refinements. All transformations from solvated or hydrated to anhydrous phases are realised without any symmetry change and the trans or cis connection of the TiF6 octahedra is maintained together with the overall features of the 3D networks. The final loss of water molecules induces a condensation reaction that implies the connection of the trimers by fluorine atoms; the structures of the anhydrous phases Zn3TiF7(taz)3 are then described by Zn3N9F4 trimers. 1H and 19F MAS NMR studies, coupled with DFT calculations of NMR parameters, confirm the water loss and support the strutural models while evidencing both the positional disorders, more likely of the organic parts, and the F motions within TiF6 octahedra.

Groundwater is a pivotal resource for many human populations and ecosystems. However, in groundwater sciences (hydrogeology), there remain many challenges in understanding key processes; including groundwater origins, water fluxes, and controls on water quality. The stable isotopes of water are naturally occurring, form part of the water molecule, can be measured at high spatial and temporal resolutions and have predictable fractionations that may be used to understand key water cycle processes. Such qualities mean that stable isotopes are a key tracer in defining the spatial and temporal heterogeneity of groundwater systems. This article provides an overview of the use of stable isotopes to analyze (i) groundwater recharge from both rainfall and irrigation water, and presents case studies that highlight the use of stable isotopes to determine the frequency, rapidity, and origins of recharge; (ii) groundwater flow pathways including paleo‐groundwater and mixing processes, and case studies of deeply circulating mineral waters, groundwater mixing, and origins of paleo‐groundwater; (iii) groundwater discharge via evaporation, surface waters, and case studies that highlight the modeling of dynamic tropical river inflows and submarine groundwater discharge; and (iv) groundwater salinity, including a comparison of processes driving salinization in two regional groundwater basins.

Accelerated aging test based on the AEIC CS8 AWTT (Accelerated Water Treeing Test) protocol was carried out on both standard and reduced-wall high-stress MV TRXLPE cables with different insulation thicknesses. Results were compared with existing data for cables with different insulation types. Furthermore, a comprehensive statistical analysis based upon the maximum likelihood method was applied to reveal the life expectancy of reduced-wall high-stress TRXLPE cables as compared to the standard wall cable. This comparison was also made with previous ACLT (Accelerated Cable Life Test) results.