Time-dependent methods to evaluate the effects of urban sprawl on groundwater quality: a synthesis

Freshwater resources are threatened worldwide with unknown and unpredictable fate, due to non-stationarity and change of water cycle dynamics, and increasing demand resulting from population growth and economic expansion. Thus, practical actions, strategies and solutions are necessary to ensure the short-term and long-term provision of adequate, affordable, accessible and safe freshwater supply to meet the needs of the growing human population and ecosystems. Since the mid-1950s, Europe is experiencing the phenomenon of urban sprawl, characterized by an unplanned incremental urban development, no more tied with population growth (EEA 2006). Impacts of urban sprawl threaten both the natural and rural environments and the quality of life for people living in cities, with worsening of air quality, and surface- and groundwater quality and quantity. For the protection of groundwater, the European Union issued a series of Directives (Water Framework Directive, 2000/60/EC; Groundwater Directive, 2006/118/EC) that require member states to achieve a good chemical status of their groundwater bodies and the identification of areas where groundwater suffers increasing trends in contaminant concentrations. In order to cope with EU Directives, a time-dependent approach for groundwater vulnerability assessment is developed to account for both the recent status of groundwater contamination and its evolution in the Po Plain area of Lombardy Region (northern Italy). Such approach takes the advantages of a Bayesian spatial statistical method to assess groundwater vulnerability and satellite scatterometer data to delineate urban areas and monitor their evolution. The proposed approach can determine potential impacts of contamination events on groundwater quality, if policies are maintained at the status quo or if new measures are implemented for safeguarding groundwater resources.