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Soil Erosion by Rainsplash

BACKGROUND

The detachment of soil by raindrop impact is an important transport mechanism within the process of soil erosion. Not only is the energy available for raindrop detachment several orders of magnitude greater than that available for interrill and rill erosion, but also much of the sediment transported through runoff processes is initially detached by raindrop impact. Consequently, further understanding of the raindrop-detachment process is fundamental to the development of soil-erosion models and their predictive capabilities.

PARTICLE DETACHMENT DUE TO RAINDROP IMPACT

Using high speed photography we have imaged the effect of raindrop impact on particle transport. Sediment particle size, relative to the raindrop diameter, has a dramatic effect on the number of ejected particles, their trajectory, velocity and overall displacement.

TWO DIMENSIONAL TRAJECTORY ANALYSIS

Image sequences can be analysed using particle identification algorithms to identify individual particle trajectories and velocities. This analysis results in a two dimensional projection of the particle paths as they are ejected from the surface.

THREE DIMENSIONAL TRAJECTORY ANALYSIS

Two dimensional measurements do not provide a full understanding of particle transport. Using multiple, high-speed cameras enables measurement in all three components of space. The technique works by using images from three calibrated cameras to triangulate the position of each particle in free space.

This experimental arrangement and subsequent analysis provides data on particle trajectory and velocity during the impact, detachment, transport and deposition processes.