A step towards the systematic reconstruction of the Italian pluviometric and thermometric heritage: the ANNHYDRO project

The reconstruction of historical hydro-meteorological records is crucial for assessing long-term climate variability and for supporting adaptation policies. This paper introduces a recent and comprehensive effort to rescue the Italian climate heritage contained in the hydrological yearbooks printed in the 1920–1990s. Conducted within the framework of the ANNHYDRO project, this study describes the activities adopted for recovering daily data of rainfall and maximum-minimum temperature. Over 1 300 000 references to rainfall data and 110 000 references to temperature data were inventoried, assembled into gauge-specific series and georeferenced to build a comprehensive database. The historical evolution of the hydrological yearbooks is outlined, highlighting how historical monitoring and reporting practices have shaped the spatiotemporal availability of observations and contributed to the Italian hydrological heritage. The critical role of source traceability and metadata consistency, ensured by the one-to-one linkage between original publications and their digital counterpart, is discussed along with potential applications of the database.