Sustainable groundwater management based on probabilistic risk analysis

Risk assessment related to the qualitative/quantitative status of groundwater is a controversial issue, compared to which it is difficult to identify an exhaustive approach. A key factor for assessing vulnerability of aquifers is the analysis of natural renewal capacity associated with the quantity of available resource and compared to the overall water demand. Groundwater recharge is a complex process to analyze because it varies in space and time, and may be severely affected by future scenarios related to climate change and population dynamics. At the same time, local and diffuse contaminations may threaten the quality of groundwater availability with respect to the standards provided to the different uses and represent a critical environmental issue. Consequently, even if there are many studies dealing with groundwater vulnerability, the definition of a shared approach capable of (i) exhaustively describing in an integrated framework the phenomena occurring in different hydrogeological and climatic contexts and (ii) considering all the significant uncertainties according to a stochastic method, has not yet been achieved. In order to address these points, this thesis suggest an innovative methodological framework in which application of uncertainty quantification is applied both to parametric uncertainty, which is relevant to subsurface flow and transport processes, and to the projections of climate change scenarios. In support of this, an algorithm is applied and further developed based on metamodeling techniques to accelerate risk and global sensitivity analysis. The algorithm is applied to different case studies in order to provide an insight on some of the main quantitative/qualitative processes that affect groundwater status, leading to potentially risk conditions. The results presented in this work lay the basis for the computation of indicators which can be used for the assessment of the vulnerability of groundwater at different scales, in accordance with the requirements of European and National Regulations.