The mass ratio of splashed particles during raindrop splash phenomenon on soil surface

Soil splash is the first step of water erosion, therefore a good understanding of it is important in order to describe this multifaceted phenomenon. One of the methods describing this process is the use of splash cups, which allow us to determine the mass of soil material ejected by the impact of water drops. The aim of this study was to determine the mass ratio of splashed particles during raindrop splash on the soil surface, including their division into a splashed liquid phase and a solid phase. The investigation was carried out using three types of soil with different particle size distributions. In the first stage of the experiment, three initial moisture contents were applied (pressure head equal to 0.1 kPa, 1.0 kPa and 3.16 kPa) and the second stage measurements were based on the soil with the highest splash efficiency in the case of the different kinetic energy of the impacting drop. It was found that: (i) the texture of soil sample had a significant effect on the mass of splashed material; (ii) the lower the initial moisture content of the sample, the lower the mass of splashed material; (iii) the highest values of the mass of splashed material (both the liquid phase and solid phase) were obtained for soil with the highest sand fraction; (iv) for all types of soils, the mass of the splashed water was significantly larger than the collected mass of splashed soil; (v) the ratio of splashed masses (the proportions) was dependent on initial moisture content for soil with a higher amount of finer fractions. The obtained results are important for the physical description of the splash erosion. For instance, the knowledge of the masses of solid (soil) and water parts of the ejected material and their ejection kinetic energy will allow the estimation of the total energy needed for the displacement of splashed material. Moreover, the investigation of the water phase in the splash phenomenon is significant because of the transport processes of pollutants and pathogenic microorganisms.