Spatial and temporal analysis of soil moisture patterns in an Alpine site in north Italy

Soil moisture represents a crucial factor in the mass and energy exchanges between land and atmosphere. Thus, the knowledge of its spatial and temporal dynamic is fundamental for several hydrological, agricultural and climatological applications. The purpose of this study is to shed light on soil moisture patterns at catchment scale in alpine environment with focus on the role of climate, soil and topography. For this purpose, a dataset of 13 measurement points at two different depths for two years have been assessed. The analyses highlight significant differences in soil moisture at 5 and 20 cm, showing diverse influence of climate, topography and soil type on the two. We found that climate factors in the shallow layer contribute to 75% of the soil moisture variance and only 25% is related to topography and soil. On the other hand, at 20 cm the climatic and the time-invariant components (topography, soil, etc…) have almost equal weights in determining soil moisture spatial variance. The analysis on seasonal basis showed the presence of frozen-related phenomena during the winter season, which prevented a clear understanding of the diverse factors on the soil moisture spatial distribution and opened new potential researches on this topic. By contrast, during the summer season well-defined soil moisture patterns mainly controlled by climate and land use were observed. The presence of weak correlations with land data and high covariances during dry periods confirms that soil moisture is the result of an interaction of multiple components rather than the result of single controlling factor. The study extends the knowledge of soil moisture dynamic in alpine environment, confirming some outcomes found in previous studies and providing new evidences on site dependency. Moreover, a database for further hydrological researches, as well as practices for future surveys, have been settled.