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Keywords:

  • salinization;
  • saltwater intrusion;
  • geostatistic;
  • coastal aquifer;
  • Jorf;
  • Tunisia

Abstract

Marine intrusion is the most serious problem facing the coastal Jorf shallow aquifer, located in south-eastern Tunisia on the Mediterranean Sea. Jorf Aquifer is intensively exploited to supply the growing needs of agriculture and domestic sectors. This work proposes a multidisciplinary investigation, involving hydro-geochemical, geoelectrical survey and geostatistical techniques for modelling the saltwater intrusion. For this purpose, 36 water samples were conducted and analysed. Electric conductivity, pH, total dissolved solids and major ions were measured and analysed. Pie and Durov Diagrams, Q-mode hierarchical cluster and geostatistical analysis were considered to identify the main groundwater mineralization processes. Results revealed that the Na-Cl-Ca-SO4 is the dominant water type suggesting that dissolution of halite and gypsum was the main mineralization source of groundwater in the central and southern part of study area. However, saltwater intrusion was shown to control groundwater quality essentially in coastal areas. Variographic analyses were used to select the variographic model that best fits the spatial development of apparent resistivity. Kriged apparent resistivity profiles showed an abnormal decrease of resistivity values in the coastal zone, implying highly saline water because of seawater intrusion. Apparent resistivity values also decrease considerably in the faulted areas, suggesting a contribution of faults to seawater intrusion. Finally, saltwater mixing ratio was computed for each sample, and a refined seawater intrusion map was developed. Copyright © 2012 John Wiley & Sons, Ltd.