Soil-surface roughness (SSR) are vertical variations present in the micro- and macro-relief of a soil surface, as well as their statistical distribution.
[1] The two first classes account for the so-called microroughness, which has been shown to be largely influenced on an event and seasonal timescale by rainfall and tillage, respectively.
Microroughness is most commonly quantified by means of the Random Roughness, which is essentially the standard deviation of bed surface elevation data around the mean elevation, after correction for slope using the best-fit plane and removal of tillage effects in the individual height readings.
[2] Rainfall impact can lead to either a decay or increase in microroughnesss, depending upon initial microroughness conditions and soil properties.
However, a recent study which examined the response of smooth soil surfaces on rainfall showed that RR can considerably increase for low initial microroughness length scales in the order of 0 – 5 mm.