Groundwater flow and transport processes

Research focus

The Peer review has evaluated this group as Excellent

The area of analysis of variably saturated flow and contaminant transport in heterogeneous natural aquifers, and characterization of geologic media is strongly active within the Department. Due to the nature of the research line, interdisciplinary expertises are required, together with a strong level of integration. These include knowledge and understanding of hydrogeological and geo-chemical processes, hydraulic and geological aspects, as well as a strong analytical and numerical modeling abilities, and field and laboratory-based expertise. These competences are currently present, albeit with various emphasis, in the group. The main objective is to understand the fundamental mechanisms governing processes of flow and transport of passive and reactive contaminants within the subsoil to provide the bases for management and development of technological tools to mitigate the impacts of contaminant fluxes on the water system. Main emphasis is devoted to process understanding and modeling of the key flow and geochemical processes occurring in natural aquifers. These activities are performed in the framework of ongoing collaboration with international institutions, as testified by the production of joint publications which have appeared (or are in the process of appearing) on major international journals (as documented by listed references). We start from the premise that quantitative analysis of heterogeneous aquifers is an extremely complex issue, mainly due to the fact that we are usually working under conditions of data scarcity. Parameters like hydraulic conductivity (or transmissivity) and porosity are of interest since they control groundwater and solutes’ paths, and rate of dispersion of solutes on various scales. Inclusion of relevant geological features in a model is essential in a proper characterization of a natural aquifer. The importance of properly representing stratigraphic aquifer structures at different scales of observation is recognized both in oil-reservoir and in aquifer modeling. Information used to designate internal boundaries between hydro-stratigraphic units includes geologic data and conceptual models. Information coming from various sources of data (including geophysical ones, sedimentological information and pumping test analyses) and spanning across a variety of scales are synthesized to obtain a clearer picture of an aquifer at different scales and various levels of resolution. Proper and reliable characterization techniques are then incorporated in the context of analysis of transient and steady state flow. Modeling of flow is performed in a stochastic framework, via Monte Carlo and moment equations-based methodologies. New frontiers have been explored in the analysis of well testing procedures in heterogeneous aquifers and in the solution of inverse problems of saturated groundwater flow. Along these lines, geostatistical inverse procedures are integrated with moment equations of flow to yield detailed estimates of how parameters vary in multi-dimensional space, as well as measures of corresponding estimation uncertainty. Stochastic theoretical models computational methods have been developed for prediction of flow, well catchment extent and contaminant time-of-residence in heterogeneous aquifers under data scarcity and uncertainty, in the presence of a variety of measured data, together with the quantification of the concept of risk associated with such predictions. The research is aimed at improving the understanding of the impact of the key hydrogeological parameters affecting the protection of groundwater sources and to develop reliable probabilistic methods to quantify uncertainty associated with predictions. These tools have been employed to develop sets of guidelines and protocols to be used in the context of probabilistic assessment of source protection. Analytical and numerical methods for flow and transport models are developed and applied to field cases. Effective/equivalent/apparent parameter approaches are pursued as well as probabilistic models of flow and transport in heterogeneous media. This is integrated within a risk analysis framework, in order to estimate related dangers for human health. The conceptual framework for protection of drinking wells has been established and multi-dimensional (probabilistic) models have been developed. Geochemical processes and their effects on aquifer hydraulic properties are analyzed. Protection of coastal aquifers is also studied, with the aim of quantifying saline intrusion (i.e., density driven flows) and its effects on the environment. This body of knowledge is then synthesized in the broad framework of integrated modeling of surface water-soil-groundwater system functioning. In summary, the activity mainly focuses on the changes of physical, chemical and biological properties of soils caused by land use practices or other perturbations and their impact on water quality, water quantity, and on the development of integrated soil-water numerical models.

Dipartimento di afferenza

Dipartimento di Ingegneria Idraulica, Ambientale, Infrastrutture Viarie, Rilevamento (DIIAR)

Docenti afferenti

Full Professors
Alberto Guadagnini
Silvio Franzetti
Enrico Orsi
Assistant Professors
Monica Riva