Tecniche di Analisi Spazio-temporali e matematico-statistiche per la valutazione di reti di monitoraggio delle acque sotterranee e relativa ottimizzazione: un caso di studio

This study has the aim of comparing critically the two groundwater monitoring networks located in Modena plain (Central Italy), in order to assess their consistency and to give suggestions to perform the monitoring. The data set used, related to water table elevation and nitrate concentration referred to spring and autumn sampling seasons throughout a 7 years period (1990-1996). The temporal behaviour shows a tight increase of values for parameters; the two networks appear consistent for water table elevation the contrary they seems to measure different situations for nitrates. A geostatistical approach of the problem has allowed observing that both the variables are stationary within a distance of about 20 km, so it has been possible to reconstruct and to map the spatial variability by ordinary kriging. Multivariate statistical analysis techniques have been applied to a suitable data set: only in the case of water table elevation the wells of the existing networks have been easily grouped in two homogeneous clusters; factor analysis has suggested the most representative sampling points for each cluster. Another criterion, based on nitrates pollution degree, was applied for choosing some wells on which make more frequent samplings.