Interaction between groundwater and surface water : the case study of Lombardy region, Italy

Water is one of Lombardy's most important resources and its use is related to potable, industrial, agricultural, hydroelectric and recreational uses. Lombardy is the most populous Italian region (about 50), both in terms of surface and volume (40% and 63% respectively of the national total). The overall length of the natural watercourses reaches approximately 6,000 km. Additionally, there is an extremely large network of irrigation and reclamation channels (about 200,000 km of censuses), which allows to keep alive and efficient agricultural activity despite the intensive urbanization of the territory. Groundwater and springs are also an important resource that historically satisfies the broad drinking, industrial, irrigation and, more recently, cooling needs. Due to the widespread urbanization of the territory, the industrialization and the spread of agro-zootechnical activities, water resources in Lombardy need constant monitoring and protection interventions. Surface water bodies are the final delivery of domestic and industrial waste and are sometimes the subject of accidental or unintended contamination. Subterranean bodies may be subject to quantitative impoverishment, in cases of excessive withdrawals, and qualitative degradation due to the presence of punctuated or diffuse sources of contamination. In this study a total of 1,376 samples of groundwater and surface water were derived from the monthly monitoring activity, conducted by ARPA, during 2015. After applying the correlation analysis, PCA and cluster analysis, the results show that the groundwater contribution to the total pollutant load of the rivers and surface water can play a significant role in water contamination. In urban area (Milan-Metropolitan area), most of contaminations such as fertilizers, Cl and nitrate are coming from the sewage effluents, municipal landfill leachate, roads and railways. Besides, urban pollution effects, in some area high concentrations were found that are a consequence of natural process of the region (e.g. the As case in the area of the Cremona province). Assessment of the pesticide and specially glyphosate shows that in several cases pollution levels could be attributed to a non-agricultural use of glyphosate. In fact, many monitoring stations classified polluted or highly polluted are located in highly urbanised areas or near railways or major roads. The results show that the amount of precipitation have changed the characteristic of the groundwater elements in 2015.