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Soil erosion is a serious ecological and environmental problem, and the main cause of land degradation in many ecosystems at global scale. Detachment of soil particles by raindrop splash is the first stage in the soil erosion process. A review of the scientific literature published in peer-reviewed international journals (ISI) over the last decades on splash erosion research sheds light on the current scientific knowledge on this topic. In addition, it highlights the research gaps and unanswered questions in our understanding of soil erosion processes due to splash. In this literature review, a bibliographic search in Web of Science by the Institute for Scientific Information (ISI) database was carried out on August the 9th, 2016, that returned 669 papers containing the words "splash erosion". The research found was categorised according to a number of criteria: i) devices used to measure splash erosion, ii) advantages and disadvantages of these devices, iii) splash erosion studies by country, iv) date of publication of the first article, v) evolution of the number of articles published in each ten-year period, vi) concepts studied, vii) keywords, viii) authors, ix) number of citations, and x) most cited articles. After this review a synthesis of the information that the science has published about splash erosion was made in order to improve our understanding about splash erosion, by identifying the research questions that still remain unanswered today about the first detachment mechanism. From this review several issues were found important for the advancement of this research topic: a) further study of the known basic factors influencing splash erosion; b) description and quantification of sources of uncertainty about the measurement of different variables; c) to understand the influences that the chosen research approach by individual researchers will have in the final result; and, d) to study the impact of drivers or mitigation techniques that may affect splash erosion.

In the context of global warming, it is a well-known fact that there is an increase in precipitation in middle latitudes. Convective phenomena have also been on the increase in the past few decades. It is gradually becoming more difficult to characterize climatic trends in middle latitudes. Data show that there may be different results depending on the study zones. Thus, it is interesting to study climatic changes in recent precipitation series, especially if we can have at our disposal a dense network of rainfall stations with reliable precipitation series.The analysis of precipitation series in 333 rainfall stations from 1961 to 1990 has revealed that summer precipitation shows a statistically significant trend in wide areas of Mainland Spain. In the months of July and August, the precipitation is exclusively convective. In those months, the precipitation increased in 20% of the southern areas, that is, in those areas where temperatures are on average higher. June and September present different trends showing a decrease in precipitation in 10% of the territory.

Annual, seasonal and monthly rainfall trends from 1961 to 2006 period were analysed in this study by applying various statistical tools to data from 553 Spanish weather stations. The magnitude of the trends was derived from the slopes of the regression lines using the least squares method, while the statistical significance was determined using the non-parametric Mann-Kendall test. Geostatistical interpolation techniques were applied to generate rainfall trend surfaces. Combining classic trends tests and spatially interpolated precipitation permits the spatio-temporal visualization of detected trends. Updated trends reveal that rainfall is generally decreasing in January, February, March, April, and June. Around 61, 44 and 12% of the whole territory is evidencing significant negative trends in February, June and March, respectively. Significant precipitation decreases are also noted in more than 28% of Spain in summer and winter. On the contrary, rainfall is significantly increasing in October in more than 21% of Spain and areas mainly located in north-western areas. May, August, September and autumn also show significant positive trends in the period 1961-2006, although the percentages are lower than for negative trends. Finally, the annual precipitation is significantly decreasing in 11% of the territory.