Methodical investigation on the applicability of fluorescent tracers to measure raindrop-impacted flow erosion

Knowledge about the movements and behavior of soil particles in a soil erosion event is still very limited. The reason for this is the lack of information about the physical conditions, like raindrop size or rain intensity, and the behavior of the soil particles under these conditions. In this paper, a new method with an experimental setup is presented that enables the optical recording of fluorescent tracers. The experimental setup consists of a rainfall simulator, a specialized raindrop-impacted flow erosion flume, a commercially available camera and two UV lamps. The tracers were selected for their similar properties with soil particles, so that their behavior most closely mimics the activity of soil particles. Using specially designed particle tracking open-source software combined with self-written data analysis programs, numerical and visual data on soil particle transport paths and velocities are generated. Validation of the new method was possible due to the different transport paths and velocities of soil particles of diverse grain size which could be measured and calculated on two pure sand substrates of two different grain sizes.