in the study of coastal plains affected by soil and water salination, a knowledge of several geological aspects, such as structural features, depth to basement, stratigraphy of sedimentary cover, relationships between the phreatic aquifer and underlying aquifers, and the latter's structure, is basic to gaining an adequate understanding of both the causes and possible evolution of salination. In this framework, geophysical techniques can play a very important role. \ud \ud To improve the available geophysical information about the Muravera coastal plain, Sardinia, Italy, which is affected by severe soil and water salination, previously acquired electrical resistivity, reflection seismic and gravity data have been reprocessed, and a new seismic reflection survey has been conducted. Moreover, in order to give better support to the geological and hydrogeological interpretation of geophysical data, three boreholes were drilled. Reprocessed electrical data indicate the presence of a wide, electrically homogeneous low-resistivity zone associated with salination phenomena. Reprocessed reflection data provide useful information on the near-surface stratigraphy. The combined interpretation of resistivity and seismic results, supported by one calibration borehole, elucidates the relationships between the phreatic aquifer and the underlying confined aquifer. A new seismic reflection survey gives information on the depth to, and structure of, the Paleozoic basement, as well as on stratigraphic conditions of Pleistocene-Holocene sediments. Finally, the combined interpretation of seismic, gravity, and well data results in a geological section containing most of the information considered essential, such as the interface between Holocene alluvium and Pleistocene alluvium, the thickness of the latter, and the structure and composition of the Paleozoic basement. \ud \ud The work as a whole shows how the combined application of geophysical techniques can in this specific situation provide wide-ranging and high-quality information that is essential for the realistic mathematical modeling of aquifer contamination, and can enable the rational planning of exploratory drillings

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The aim of this article is to show how the application of geophysical techniques at different scales, integrated with hydrogeological and borehole information, can be effective in defining a peculiar hydrogeological context in which cover-collapse sinkholes often occur. The study area lies in SW Sardinia and is characterized by the cropping out of the Palaeozoic basement locally covered by Tertiary–Quaternary sediments. The gravity method,even used alone, proved to be very effective in detecting the regional geological structures to which sinkholes are related, while local details are well defined by means of seimic techniques.\ud The historical analysis of phenomena, the geological knowledge of the area and the results of geophysical surveys allowed to draw a preliminary hazard map.\ud This map shows a belt of high risk, and also suggests the areas in which further geophysical and geotechnical investigations should be carried out to estimate the depth of the bedrock, to which sinkholes are related.\u

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