When a flood occurs, the stream is getting much more water, and on the parts where the angle of fall is greater and the stream is faster, because of the greater amount of water, and thus force, it managed to take with it much bigger amount of sediments, and also much bigger pieces of it.
The transportation depends on the speed and force of the water, and when there is a flood. both of those are bigger, so the stream is able to carry more sediments over a longer distance, but also over a wider area as the waters are getting out of the normal river flow and flood the valley.
Soil erosion is a gradual process of movement and transport of the upper layer of soil (topsoil) by different agents – particularly water, wind, and mass movement – causing its deterioration in the long term.
In other words, soil erosion is the removal of the most fertile top layer of soil through water, wind and tillage.
