Hydrological monitoring of agricultural terraces in different land use conditions at the Cinque Terre National Park (NW Italy)

In many hilly and mountainous regions worldwide, the construction technique of dry-stone walls constitutes tangible evidence of the close connection between traditional knowledge and sustainable land management, which has been recognized as an Intangible Cultural Heritage of Humanity by UNESCO. Since ancient times, dry-stone walls have been essential to facilitate cultivation of rugged environments by creating terraces that optimized land management, improved water management, prevented erosion and supported the needs of local communities.

However, the gradual abandonment of agricultural practices, mainly attributable to the intrinsic difficulties of cultivation in these areas and socio-economic changes, has triggered a progressive and widespread degradation of the dry-stone wall terrace complexes. This process can be further exacerbated by the effects of high-intensity rainfall events, which can accelerate the degradation of terraced slopes, increasing the frequency and magnitude of slope instability phenomena, also involving extensive dry-stone wall collapses. These phenomena have generated significant fertile soil losses along with economic and cultural impacts, threatening the preservation of an invaluable heritage.

The primary objective of this study is to analyse the influence of different land management practices on the hydromechanical characteristics of terraced soils and, consequently, on gaining insights into the factors controlling the occurrence of rainfall-induced instability processes of terraced slopes, such as shallow landslides. The research activities are in the framework of the project Stonewalls4life, a LIFE EU-project focused on the role of drystone walls in increasing the resilience of rural territories and in counteracting the impacts of climate change. The investigation is conducted at two monitoring sites situated along a terraced slope in the Manarola area, which is located within the Cinque Terre National Park (Liguria Region, NW Italy), where terraces constitute a characteristic feature of the local landscape and cultural heritage.

The selected monitoring sites consist of terraces having different land uses, namely currently cultivated vineyard and abandoned vineyard since several decades. To achieve the research purposes, hydrological monitoring instruments have been installed at both sites to monitor soil-water interactions, specifically measuring soil moisture content, soil temperature and suction during rainfall events. The monitoring network also includes a complete weather station to collect meteorological data (e.g., rainfall intensity, air humidity, air pressure, wind speed). In this contribute, the multi-sensor hydrological data acquired over a period longer than 2 years are presented along with the investigation of the hydrological response of the monitoring sites to rainfall at different time scales (i.e., seasonal and single rainstorm).

The obtained results will be useful in the frame of hydrological modelling of terraced slopes, allowing to identify the areas most prone to instability. Eventually, the research activities will represent a useful guide for the formulation of targeted strategies aimed at improving the management of agricultural terraces in the study area.