22 Preliminary Results of a Comparison Study Between Two Independent Snow Networks in North-Western Italian Alps (Piemonte Region) Fiorella Acquaotta, Nicola Colombo, Simona Fratianni, Vincenzo Romeo and Secondo Barbero Abstract The snow represents a fundamental resource for hydro-power generation, irrigation, domestic and industrial water supply. The knowledge of behaviour and trends of this meteorological variable is very important for the human society and mountain system. Thus, climatologists are increasingly interested in studying changes in the intensity, frequency, duration and spatial distribution of snowfall and snow depth. Unfortunately, long instrumental climate records are usually affected by non-climatic changes (inhomogeneities), which compromise the quality of these studies. In order to analyse non-climatic biases, such as the influence of position or instrument changes due, for example, to the transition from manual to automatic measurements, we have compared the parallel measurements. The presence of two independent climate networks offers the opportunity to study the data inhomogeneity of snow records. The analyses highlight higher measured values in manned gauges respect to automatic stations. The major differences have been recorded at the beginning of the winter season, in October and April. Keywords Snow series  Parallel measurements  Inhomogeneities  NW alps 22.1 Introduction The Alps are one of the major mountain ranges in Europe. Their significance for the regional water cycle is commonly expressed in the notion ‘‘water tower of Europe’’, which hints to their climatic characteristics with abundant liquid and solid precipitations, and the role of snow and ice in storing freshwater. The long term climate dataset are essential to analyse and monitor the climate change. The quality of these measurements is governed by the accuracy of the instru- ments used in the national networks. The Italian networks have experienced many techno- logical, economical and organizational changes, which may affect the homogeneity of the record (Acquaotta et al. 2009; Venema et al. 2012). Consequently, identifying inhomo- geneities in meteorological time series is necessary to achieve a comprehensive assessment of climatic changes (Parker 1994). Therefore, it is necessary to apply a literature data review and rigorous data analysis procedures to search and detect steps due to stations relocation. In Europe the inhomogeneity problem of meteorological series has been often addressed on daily or monthly temperature and rainy F. Acquaotta (&)  N. Colombo  S. Fratianni Department of Earth Sciences, University of Turin, via Valperga Caluso 35, 25100, Turin, Italy e-mail: fiorella.acquaotta@unito.it V. Romeo Corpo Forestale dello Stato - Servizio Meteomont, Rome, Italy S. Barbero Agenzia Regionale per la Protezione Ambientale (ARPA) Piemonte - Sistemi Previsionali, Turin, Italy G. Lollino et al. (eds.), Engineering Geology for Society and Territory – Volume 1, DOI: 10.1007/978-3-319-09300-0_22, Ó Springer International Publishing Switzerland 201 113 5