Preservation of Drinking Water: Examples and Applications of New Technologies for the Quality and Quantitative Monitoring of the Resource

The availability of fresh water is essential for human consumption, agriculture, and industry. It is well-known that fresh water is an essential need for our health. Nowadays, several freshwater resources around the world are threatened as industrial and technological growth advances. Global water demand is estimated to increase by about 20-30% by 2050. In this context, developed countries suffer most from problems attributable to industrial waste, while developing countries from agricultural sources. Health problems and waterborne diseases can be prevented by taking measures and establishing resource-aware management. The task of water management companies to provide safe water at the domestic level is quite challenging and continuously needs efforts and investments for the development and implementation of new technologies. An interesting example regarding the application of new techniques for preserving water resource from both a quantitative and qualitative point of view is the one carried out in the 2018-2019 biennium on the Nossana and Ponte del Costone springs. These karst systems represent some of the most important springs in northern Italy in terms of discharges, supplying the drinking needs of more than 300,000 people in the Bergamo metropolitan area. Thanks to the joint effort between the local water company and the Università degli Studi di Milano, a monitoring campaign including 23 springs in the two basins was performed. Activities included monthly discharge measures and spring water sampling for anions, cations, and isotopes (2H, 18O, and 13C). A new index-based approach was proposed to assess the vulnerability of karst springs allowing the better definition of recharge areas (most vulnerable zones) than classical methods. Chemical-physical analysis proved the excellent quality of the resource but dating by the 3H/3He method showed a slight aging for the main springs in comparison to 2015 that needs to be investigated further. Furthermore, the Climate Change impact on Nossana spring discharge considering three IPCC scenarios was simulated by implementing a hydrological model and using the downscaled data of Regional Climate Models as input. A clear trend cannot be detected, but the simulations expected the projected mean discharges (2021-2100) to be lower than observations (1998-2017) for all the scenarios considered (3%-23%). Consistently with the precipitation trend (more long and dry summers), an increase in the duration of periods with discharges below warning thresholds is predicted after 2060. The repeated use of these tools at intervals over time can both contribute to improved management and conscious planning of spring water use and drive the search for alternative resources. This in-depth characterization approach was focused on two of the most important springs in northern Italy and is now continuing for additional catchments in the Bergamo Pre-Alps to obtain a comprehensive knowledge of the potential of all spring water resources in the region.