2d and 3d modeling of the south friuli plain aquifers.

In these years the Friuli Venezia Giulia Region has funded several researches aimed at the characterization of the Friuli Plain (FP) subsoil, which is an important aquifer seat other than, locally, a low enthalpy geothermal reservoir. The DiSGAM and DICA have been engaged by the Hydraulic Survey in order to coordinate an integrated study finalized to the FP confined and unconfined aquifer geometries reconstruction and to provide guide-lines for water rational exploitation (Agreement D,G.R. n. 1827 dd. 27.07.2007). The South FP is formed by a succession of clastic aliuvial deposits (Pllo- Quaternary), overlaying Miocene molasses, Paleogene turbidites and the carbonate platform basement. It is characterized by the presence of a resurgence transition belt, at which the gritty northern area, hosting mainly unconflned aquifers, changes over to a clayey-sandy alternated system, hosting multi-layered confined ones. In order to define underground aquifer relations and patterns, more than 1800 stratigraphic columns ha ve been collected from different public departments' water well data base. Welllogs have been georeferred, missing elevations calculated by regional DTM, possible correspondences controlled and datasets updated. In order to better correlate spatial data a unique implemented Iithostratigraphy legend has been created from present different ones; it is composed of: Lithological Entries (relating Iithology and granulometric features; permeability linked different values are also attributed) and Description Notes (includlng accessory precious information as, for example, fractured, carsified, shell or plants rich intervals turned out to be usefull In depositional setting definition and wells spatial correlation). Wells data have been iteratively analyzed and hydrostratigraphy sequences have been interpreted accordlng to the conceptual model relating to layered shallow and dee p confined aquifers (Stefanini et al. 1977; Martelli et al., 2007 Cucchi et al. 2008); where present, A-B-C-D-E-F-G-H-I-L-M aquifers' top and bottom, other than interposed aquitards, have been well picked. Top and bottom maps have been elaborated initially through trlangulation, then from grids calculated by different algorithm methods (krigging, inverse distance, ecc), other countouring parameters (polynomial enhancement, declustering, logaritmic gridding, high fidelity, smooth grid) and poligon filterings. Thicknesses have been calculated by grids mathematical subtraction. Obtained maps have been compared and matched with geological cartography, geophyslcal data and geothermal maps (Nicolich et al, 2008), Grado 1 (Della Vedova et al, 2008) and deep wells. Maps should further improve with upcoming wells data. Hydraullcally connected areas have been identified in cross correlatlng sections; permeability domains, different texture features and heteropic interdigited layers have been highllghted. Extent outlines of main hydro-stratigraphic units ha ve been reconstructed; top surfaces and thicknesses values ha ve been mapped. Ali these studles are usefull for reconstructing the availability groundwater resource and to evaluate the sustainable exploltation of the resources (water quantities). References Cucchl F., Franceschini G., lini L. (2008): Hydrogeochemical investigations and groundwater provinces of the Friuli Venezia Giulia Plain aqulfers, northeastern Italy. Environmental Geology 55, 985-999. Della Vedova B, Castelli E, Ci molino A, Vecellio C, Nlcolich R, Barison E. (2008): La valutazione e lo sfruttamento delle acque geotermiche per il riscaldamento degli edifici pubblici. Rass. Tecn. FVG, 6/2008, 16-19. Martelli G., Granati C. (2007): Valutazione della ricarica del sistema acquifero della bassa pianura friulana. Giornale di Geologia Applicata, 5, 89-114. Nicolich R, Della Vedova B, Barison E, Ci molino A. (2008): Le acque calde della bassa pianura friulana e la loro potenzialità. Rassegna Tecnica FVG, 3/2008, 8-12.