The Spatial-Temporal Variability of Nitrates in a Section of the Cuneo Plain (North West Italy)

Abstract

The study of an aquifer system is very important, but also very complicated because of the high temporal and spatial variabilities of a system and because of the phenomena that are at play within the system. It is from these problems that the necessity arises of finding methods that are able to extend point knowledge to an entire area, while maintaining all the parameters that play a role, while starting from a limited amount of available information. It is therefore necessary to make use of a mathematical treatment of the data, assuming that each measurement point carries with it the information relative to a certain neighbourhood of an amplitude that has to be defined. Among the different methods that are available to interpolate data, the best are those of a geostatic nature that are based on a probabilistic approach and which allow models to be used that reflect the uncertainties of the characteristic parameters of an aquifer and on how the physical phenomena evolve as a whole. The first and most important step of a geostatic study is the characterisation of a spatial, temporal or spatial-temporal phenomenon. This present work falls into this ambit. It was carried out in a sector of the Cuneo Plain (NW Italy) where the spatial and temporal variability of nitrate concentrations was evaluated in a surface aquifer together with the hydro-chemical characteristics of the water resource under examination. The analysis of the nitrate concentrations showed that these increase going from SW to NE, in correspondence to the increase in human and zootechnical activities, that is, from the piedmont zones to the central zones of the plain according to the direction of the groundwater flow. From the data that were obtained, it results to be impossible to determine the quality of the groundwater resources in a definitive way because of the great variability of the phenomena and it is therefore necessary to identify a congruous number of measurement points with the purpose of describing, as accurately as possible, the state of the system in time, whilst also taking into consideration the economic aspects that such a proposal would involve.