Comparison the methods of roughness measurement; pin-meter, roller chain and assessment shelter angle index in wind erosion researches

Roughness is an important surface feature in understanding the mechanism of soil erosion by wind and water. Measurement techniques can be classified by measurement dimension and sensing type. Pin meter and roller chain are widely used in field investigations because they facilitate quick and simple data acquisition. The objective of this study was to compare the pin meter, roller chain techniques and also to introduce the shelter angle index. A new surface roughness index, Cumulative Shelter Angle Distribution (CSAD) integrates the oriented and non-oriented roughness into a single index, which is defined as the maximum angle from the horizontal between measured elevation points with a 0.35m distance along a transect resting on soil surface. The cumulative shelter angle distribution is adequately described using a two parameters Weibull function. Comparison of the pin meter and roller chain showed the non-significant relation, although the roller chain is very fast and quick data acquisition. The results of CASD showed that more than 87% of studied surface area have shelter angle less than 15 degrees and also are susceptible to the impact of saltating soil particles.