Rainfall is one the main drivers of soil erosion. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the R-factor in the USLE model and its revised version, RUSLE. At national and continental levels, the scarce availability of data obliges soil erosion modellers to estimate this factor based on rainfall data with only low temporal resolution (daily, monthly, annual averages). The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based on the best available datasets. Data have been collected from 1541 precipitation stations in all European Union (EU) Member States and Switzerland, with temporal resolutions of 5 to 60 min. The R-factor values calculated from precipitation data of different temporal resolutions were normalised to R-factor values with temporal resolutions of 30 min using linear regression functions. Precipitation time series ranged from a minimum of 5 years to a maximum of 40 years. The average time series per precipitation station is around 17.1 years, the most datasets including the first decade of the 21st century. Gaussian Process Regression (GPR) has been used to interpolate the R-factor station values to a European rainfall erosivity map at 1 km resolution. The covariates used for the R-factor interpolation were climatic data (total precipitation, seasonal precipitation, precipitation of driest/wettest months, average temperature), elevation and latitude/longitude. The mean R-factor for the EU plus Switzerland is 722 MJ mm ha(-1) h(-1) yr(-1), with the highest values (>1000 MJ mm ha(-1) h(-1) yr(-1)) in the Mediterranean and alpine regions and the lowest (<500 MJ mm ha(-1) h(-1) yr(-1)) in the Nordic countries. The erosivity density (erosivity normalised to annual precipitation amounts) was also the highest in Mediterranean regions which implies high risk for erosive events and floods.

Earlier reports indicated some specific isolated regions exhibiting a paradoxical increase of extreme rainfall in spite of decrease in the totals. Here, we conduct a coherent study of the full‐scale of daily rainfall categories over a relatively large subtropical region‐ the Mediterranean‐ in order to assess whether this paradoxical behavior is real and its extent. We show that the torrential rainfall in Italy exceeding 128 mm/d has increased percentage‐wise by a factor of 4 during 1951–1995 with strong peaks in El‐Nino years. In Spain, extreme categories at both tails of the distribution (light: 0‐4 mm/d and heavy/torrential: 64 mm/d and up) increased significantly. No significant trends were found in Israel and Cyprus. The consequent redistribution of the daily rainfall categories ‐torrential/heavy against the moderate/light intensities ‐ is of utmost interest particularly in the semi‐arid sub‐tropical regions for purposes of water management, soil erosion and flash floods impacts.

This paper contains a preliminary analysis of flood risk in Mediterranean countries, conducted within the framework of the FLASH European Project. All flood events recorded between 1990 and 2006 in the Mediterranean region have been included in the study. Results of previous international projects (STORM, SPHERE, AMPHORE, RINAMED and MEDEX), as well as information provided by FLASH Project partners and data included in scientific papers were the main source used in building this database. All the above information had been dispersed in various places, and an attempt was made here to create, for the first time, a verified and complete single database for the entire Mediterranean region. The work analyses the spatial and temporal distribution of flood events, as well as their social impact, with special attention to certain case studies that have been analysed in detail.