Indagini geofisiche e rilievi geologici per scopi idrogeologici in un\'area ad est di Lecce


È stato condotto uno studio geofisico di dettaglio,integrato da preliminari indagini geologiche,in un’area campione ubicata immediatamente ad est dell’abitato di Lecce,allo scopo di ricostruirne il sottosuolo.In particolare,le indagini sono state condotte in una porzione di territorio fortemente antropizzata,laddove peraltro è ubicato il depuratore della città di Lecce,per verificare le potenzialità dell’integrazione dei metodi elettrici e sismici nella risoluzione di problemi idrogeologici.I risultati ottenuti hanno permesso di evidenziare l’efficacia dei metodi geo fisici utilizzati per la descrizione di dettaglio degli acquiferi ed hanno consentito di porre in risalto l’eterogeneità degli stessi e quindi l’inadeguatezza di studi a scala regionale per la piani ficazione del territorio.Inoltre la ef ficacia della visualizzazione dei modelli geo fisici consente una immediata lettura anche ai non addetti ai lavori.
In Italy the water resource are represented in the almost totality by the underground waters.Analogous situation finds in Apulia region and particularly in the Salento peninsula,whose the karstik nature of the subsoil causes the absence of super ficial water resources.From the sixties years to today is assisted to a notable economic and social growth,to loss of a non sustainable use of the resources,particularly soil and water.They are two the concomitant aspects that have regulated this meaningful decrement of the availability of sweet water:on the one side the demogra fic growth to which always follows one greater application of water,and from the other side the man action that polluting and therefore reduces quality and/or quantity of the water resources.Fortunately,the trail general tendency to consider the water as a boundless resource,has recently been replaced by a progressive taking of conscience of its real availability. The correct management and protection of the Apulia underground water patrimony,particularly in the Salento peninsula,represents the priority objective to perform in short-time;to obtain it can be used a double approach,realized to different scale: first one,in the regional scale a continuous control of the evolution phenomenons is performed;this control interest the availability and the quality of the underground water resources;in the local scale,therefore with greater detail, the protection initiatives of the best underground waters (used to the human consumption)are studied,to delimit the areas to safeguard. The control of the underground water resources necessarily passes from one detailed knowledge of the particular hydrogeological structures.For this purpose the geophysical methods,which allow to investigate the subsoil to elevated depths, assume increasing importance. In this paper a limited area in the salento peninsula has been considered for the above purpose.The choice of the area,over that for the facility of access,has been effected for the presence of both stratigraphical and hydrogeological data,to which to make reference,and for the existence of important anthropic structures.The applied methodology is developed therefore,previous a geologic phase of study,in the execution and interpretation of geophysical cross-sections. The geological study has consisted in a detail survey (scale 1:5000)of the considered area with particular attention to the reconstruction of the structural order. Through the use of the subsoil stratigraphical data (cores data),with the integration of the surface data,the 2D subsoil sections of the territory has been carried out. Hence geophysical survey was carried out using both the electrical resistivity tomography (ERT)and seismic (refraction and re flection)methods. The results pointed out the contribution of the effectiveness of the non-destructive geophysical methods for the knowledge of the subsoil with great detail.Integrating the electric and seismic data has been possible to point out different several characteristics of the ground water;particularly the ERT images result more effective in to underline the different degree of saturation of the formations that lodge the ground water;seismic images result instead more pro fits to point out the stratigraphy of the subsoil and the surfaces of discontinuity present between the different formations. The integrated use of the two geophysical methods is essential for a correct interpretation of the geophysical images. The results have shown as a integrated approach,geological and geophysical, to study the ground water can show some aspect that an investigation to regional scale cannot shows.

DOI Code: 10.1285/i15910725v29supp245

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