Characterization of Hydraulic Heterogeneity of Alluvial Aquifer Using Natural Stimuli: A Field Experience of Northern Italy

Abstract

This study investigates the hydraulic heterogeneity of the alluvial aquifer underneath the dam and the stilling basin of a flood protection structure in Northern Italy. The knowledge of the interactions between the water in the reservoir upstream of the dam and the groundwater levels is relevant for the stability of the structure. A Bayesian Geostatistical Approach (BGA) combined with a groundwater flow model developed in MODFLOW 2005 has been used to estimate the hydraulic conductivity (HK) field in a context of a highly parameterized inversion. The transient hydraulic heads collected in 14 monitoring points represent the calibration dataset; these observations are the results of the hydraulic stresses induced by the variations of the lake stage upstream of the dam (natural stimuli). The geostatistical inversion was performed by means of a computer code, bgaPEST, developed according to the free PEST software concept. The results of the inversion show a moderate degree of heterogeneity of the estimated HK field, consistent with the alluvial nature of the aquifer and the other information available. The calibrated groundwater model is useful for simulating the interactions between the reservoir and the studied aquifer under different flood scenarios and for forecasting the hydraulic head levels due to strong flood events. The use of natural stimuli is useful for obtaining information for aquifer heterogeneity characterization.

Groundwater Modelling in Karst Areas

“…On the whole, the papers published within this Special Issue point out the existence of a wide range of topics related to karst hydrogeology; for example, (i) a recharge estimation, (ii) unsaturated/saturated flow, (iii) flow in karst conduits in the fracture network at the interface between the matrix and conduits and (iv) seawater intrusion that can be refined exploring several types of experimental/statistical/numerical approaches. In a wider and methodological perspective, the same papers further demonstrate the added value of mixing different approaches such as (i) experimental and statistical [8], abiotic and biotic [9], carried out at field and lab-scale [10] and also highlighted the importance of the knowledge of hydraulic parameters [5,11,12].…”