Land uses and freshwater system quality of Oglio River sublacual basin (Northern Italy)

Quantifying the effects of land use and other multiple stressors, that may also act in synergy, on freshwater ecosystems is challenging, due to the complex interactions within blue water components (groundwater, lakes, rivers, springs) and to the lack of tailored field campaigns for the contemporaneous measurement of hydrological, chemical and ecological parameters. A wealth of available studies addresses a single stressor separately without exploring their concurrent effect. However, concurrent effects with several stressors, such as the release of pollutants from agricultural or industrial activities and waste water treatment plants, have not been explored at depth, so far. Additional pressures are also being exerted by population growth, urban expansion, and industrial development. The anthropogenic pressure on water resources is growing worldwide, and reducing its effects on the water ‘availability’ and quality is one of the major societal challenges. We present a part of study (Fondazione Cariplo grant n° 82014-1282) on the land uses and their impacts on blue water of the Oglio River sublacual basin. The research project aims to analyze the processes that affect blue water quality and quantity with a key focus on the interactions within its different components using the inter-disciplinary approach. The attention is focused on a typical alluvial basin in the Po Plain (Lombardy Region – Northern Italy), that is heavily impacted by land uses and, in general, anthropogenic activities, where the blue water system is composed of subalpine lakes, rivers, irrigation and drainage channels, springs and unconfined and confined aquifers, all interacting with each other. The study area shows a significant variability in terms of land and water use and hydrological driving forces: this allows us to use this basin as a benchmark for testing and validating models of ecological functioning, pollutant cycling as well as the effects of new water policies and water management strategies. The results concern integrate information and dataset, continuous in space and time, systematically collected by a ‘multitasking’ group (UNIMIB) with several expertise over the past year for a comprehensive investigation of blue water dynamics. More than 60 sampling sites have been monitored seasonally, measuring hydrological, hydrochemical (ions, nutrients, heavy metals) and isotopic features on the lake, river, aquifer, and springs to develop a three-dimensional numerical flow model producing a quantitative water balance to evaluate the sources of water, the travel time and the mixing degree between surface water and groundwater, and among the confined aquifers.