Simulazione geostatistica e modellazione del flusso in un analogo di acquifero fluviale meandriforme

A 3-D quarry exposure of historical point bar-channel sediments of the Lambro River (Po plain, Northern Italy) permits to analyse meandering river depositional elements and to assess their hydrodynamic characteristics. The work follows three main steps: i) drawing and discretization of the geology starting from 5 vertical facies maps and estimates of conductivity of every facies; ii) 3D geostatistical simulation of facies heterogeneities, based on semivariogram and transition probabilities analysis; iii) application of a 3D numerical flow model to upscale the conductivity field ad to estimate connectivity. The starting point is a sedimentological and hydrostratigraphic hierarchic model obtained after mapping of 5 quarry faces with cm-scale detail. We have recognized two main units corresponding to the exposed parts of two composite point bars with minor channel fills on top: unit A, the lower one, includes Roman-Middle Age findings and shows a composite point bar to main channel fill lateral transition, whereas unit B, the upper one, includes Renaissance Age findings and is mostly represented by a composite point bar, with chute channel scour and fills on top . The erosion surface between them, named α surface, was mapped using GPR data. Units A and B are formed by a hierarchic arrangement of depositional units, that determines the architectural heterogeneity of the aquifer analogue. Textural and poro-perm analyses allowed to define the properties of 4 basic hydrofacies with permeability contrasts by at least one order of magnitude (10-9