A first assessment of rainfall erosivity synchrony scale at pan-European scale

Soil loss by water erosion is a major land degradation processes that can locally reduce crop productivity and cause off-site negative effects such as siltation, eutrophication of waterways, flooding and terrestrial and aquatic biodiversity loss. The major driver of water erosion is the erosive power of rainfall. Using the detailed erosive events of the Rainfall Erosivity Database at European Scale (REDES), we study the characteristics and patterns of rainfall erosivity in Europe introducing the Rainfall Erosivity Synchrony Scale (Rsync). Rsync expresses the maximum radius in kilometers around a given meteorological station within which at least half of the other meteorological stations in the database also detect an erosive event. In this study we correlate the Rsync and the annual erosivity with annual number of thunderstorm days, convective and large-scale precipitation and multiple geo-morphological features such as topographic position index and terrain ruggedness index. Our analysis shows an inverse relationship between the Rsync and rainfall erosivity values in Europe. Different spatial patterns of synchrony scale are detected in Europe, which enables us to delineate areas where severe soil erosion can simultaneously occur at larger scales, e.g., large sectors of Italy, Spain, Croatia and Slovenia. Furthermore, we observe a tendency of the Rsync to decrease with convective precipitation, annual number of thunderstorm days and increase with the large-scale precipitation. On the contrary, annual rainfall erosivity increases with convective precipitation and annual number of thunderstorm days and decreases with large-scale precipitation.