Ocean Science Journal - Seasonal variations of the gonad index (GI), the biochemical composition, and the concentration of heavy metals in the gonads of the sea urchin, Paracentrotus lividus... 相似文献
Abstract The Wadi Al Ayn plain is a coastal system on the eastern coast of Cap Bon in northeastern Tunisia. The area is known for its intensive agriculture, which is based mainly on groundwater exploitation. The aim of this study is to identify the sources of groundwater salinization in the Wadi Al Ayn aquifer system and deduce the processes that drive the mineralization. Surface water and groundwater samples were taken and analysed for major ions and stable isotopes. The geochemical data were used to characterize and classify the water samples based on a variety of ion plots and diagrams. Stable isotopes are useful tools to help us understand recharge processes and to differentiate between salinity origins. The oilfield brines infiltrated from the sandy bed of Wadi Al Ayn comprise the main source of groundwater salinization in the central part of the plain, while seawater intrusion is mainly responsible for the increased salinity in the groundwater of the coastal part of the plain (at Daroufa). Citation Chekirbane, A., Tsujimura, M., Kawachi, A., Isoda, H., Tarhouni, J., and Benalaya, A., 2013. Hydrogeochemistry and groundwater salinization in an ephemeral coastal flood plain: Cap Bon, Tunisia. Hydrological Sciences Journal, 58 (5), 1097–1110. 相似文献
The subsurface data are a basic requirement for the set up of hydrogeological framework. Geographic information systems (GIS) tools have proved their usefulness in hydrogeology over the years which allow for management, synthesis, and analysis of a great variety of subsurface data. However, standard multi-layered systems are quite limited for modeling, visualizing, and editing subsurface data and geologic objects and their attributes. This paper presents a methodology to support the implementation of hydrogeological framework of the multi-layered aquifer system in Nabeul–Hammamet (NH) coastal region (NE, Tunisia). The methodology consists of (1) the development of a complete and generally accepted hydrogeological classification system for NH aquifer system (2) the development of relational databases and subsequent GIS-based on geological, geophysical and hydrogeological data, and (3) the development of meaningful three-dimensional geological and aquifer models, using GIS subsurface software, RockWorks 2002. The generated 3-D geological models define the lithostratigraphy and the geometry of each depositional formation of the region and delineate major aquifers and aquitards. Where results of the lithologic model revealed that there is a wide range of hydraulic conductivities in the modeled area, which vary spatially and control the groundwater flow regime. As well, 17 texturally distinct stratigraphic units were identified and visualized in the stratigraphic model, while the developed aquifer model indicates that the NH aquifer system is composed of multi-reservoir aquifers subdivided in aquifers units and separated by sandy clay aquitards. Finally, this study provides information on the storing, management and modeling of subsurface spatial database. GIS has become a useful tool for hydrogeological conceptualization and groundwater management purposes and will provide necessary input databases within different groundwater numerical models. 相似文献
Long-term exploitation schemes in many regions are often based solely on hydrodynamic factors, while the agricultural use of groundwater undergoes significant changes over time. The Bouhefna-Haffouz aquifer system in central Tunisia is one of those cases where an aquifer exploitation scheme was well designed hydrodynamically to address the political needs at the time. Fifty years later, a numerical groundwater model has been conducted to assess the sustainability of the scheme. Results show that the scheme aimed to lower the groundwater level to reduce overflow to Merguellil Wadi and maintain it at a level that benefits agricultural profitability. This caused loss of the Merguellil baseflow, forcing farmers to switch from traditional irrigation canals to deep wells and motor pumps, thereby disrupting the hydrological budget even further. The numerical model indicates that the flow to the wadi reached zero in 1978, the average flow by vertical leakage decreased from 8 hm3 in 1970 to 2 hm3 in 2020, and the horizontal percolation between the regional aquifer units increased from 1 hm3 in 1970 to 6 hm3 in 2020. Although the groundwater exploitation scheme was not previously considered a factor in local hydrological changes, the results of this study demonstrate the significant impact of societal behavior following the scheme’s implementation on the hydrological budget of Merguellil Wadi.
RESUMEN: En la planicie costera occidental de Bélgica, la mayor parte de la demanda de agua se abastece mediante captaciones
en lentejones de agua dulce, bajo el cordón de dunas. Debido a la sobreexplotación, especialmente durante el verano, las captaciones
están amenazadas por intrusiones de agua salada. Existe la posibilidad de utilizar recarga artificial, ya que en invierno
una gran cantidad de agua dulce superficial se vierte al mar. Se presenta una propuesta para mejorar la gestión del agua en
dicha región. Los estudios preliminares han consistido en dos ensayos: uno de recarga artificial en la zona de las dunas,
y uno de doble bombeo en un cordón arenoso cerca de un canal de drenaje en la zona pantanosa de la planicie costera. La interpretación
de los ensayos se realizó mediante modelación inversa. Los resultados del ensayo de recarga artificial han demonstrado la
posibilidad de usar recarga artificial en la zona de captación de Koksijde. El ensayo de doble bombeo ha demonstrado que el
cordón arenoso de Avekapelle, situado en la zona pantanosa, se puede utilizar como zona de captación.
RéSUMé: Dans la partie occidentale de la plaine c?tière belge, la demande en eau est pour la plupart satisfaite par des captages
d'eau souterraine. Les puits captent l'eau d'une lentille d'eau douce sous le cordon dunaire. Par suite d'une surexploitation,
surtout pendant l'été, ces captages d'eau sont menacés par une intrusion d'eau salé. La recharge artificielle de la nappe
peut être envisagée parce que, pendant l'hiver, de grandes quantités d'eau douce sont évacuées vers la mer. Une amélioration
de la gestion de la ressource en eau est donc proposée. Deux essais ont été réalisés pour une étude préliminaire: un essai
de recharge artificielle dans la région des dunes et un essai de double pompage prés d'un canal de drainage dans les polders.
Ces deux essais ont été interprétés grace à une méthode inverse. L'essai de recharge artificielle a démontré les possibilités
de recharge de la nappe pour le site de captage de Coxyde. L'essai de double pompage a montré que le d?me sableux d'Avekapelle,
dans les polders, est une région de recharge qui convient.
The Late Hercynian evolution in the French Massif Central corresponds to the transition from a LP–HT (M3 event at 314 ± 5 Ma) to a higher temperature metamorphism corresponding to the emplacement of the Velay granite dome (M4 event at 301 ± 5 Ma). This transition is outlined by the development of sillimanite folia, which represent planes of base-cation leaching, associated with ductile deformation. This evolution implies a counterclockwise retrograde path under subsolidus conditions between M3 and M4. To cite this article: P. Barbey et al., C. R. Geoscience 337 (2005).相似文献