Groundwater Dynamics and Quality Assessment in an Agricultural Area

Abstract

Problem statement: The analysis of the relationships among the different hydrogeological Units and the assessment of groundwater quality are fundamental to adopt suitable territorial planning measures aimed to reduce the potential groundwater pollution especially in agricultural regions. In this study, the characteristics of groundwater dynamics and the assessment of its quality in the Cuneo Plain (NW Italy) were examined. Approach: In order to define the geological setting an intense bibliographic analysis has been performed by the authors. This analysis was implemented by several correlated land controls and specific surveys that have permitted to analyze to certain reliability the Quaternary evolution of the entire plain sector and the current relationships among the different geological bodies that strongly affect the groundwater dynamics. Results: The Quaternary alluvial deposits overlap a Tertiary sedimentary succession through a series of erosional unconformity surfaces. These Quaternary deposits highlight a variable thickness ranging from 80-100 m in the foothills of the mountains up to a few meters in the more distal portion of the plain. In these deposits there are several unconfined aquifers which are not hydraulically interconnected due to the deep fluvial incisions that reach the underlying tertiary substrate. The Cuneo plain is intensively populated and lot of villages and farms characterize the landscape. In the overall area it is present an intensive agricultural and livestock activity predominantly represented by crops of wheat and corn and farms of cattle and pigs. All these activities represent point and diffuse groundwater pollution sources and require a considerable amount of groundwater which is withdrawn from the Quaternary aquifers by means of thousands of water wells. The groundwater quality is strongly influenced by the content of nitrates and manganese. The nitrates are linked to pollution due to agricultural activities and livestock and increase along the groundwater flow lines. The manganese content is quite high in the foothills of the mountains and in some restricted areas of the plain and appears to be linked to the natural litho logical composition of the aquifers. Conclusion: Due to high degree of intrinsic aquifers vulnerability over the entire Cuneo plain sector in order to reduce the actual groundwater pollution and the risk for human health it has to be planned several territorial suitable planning actions aimed to limit nitrates effluents and livestock untreated discharges according with the European rules.