investigation of roundness and sphericity status of Surface particle in desert pavement in different types of pediments using Powers index

The particle shape and their aerodynamic status play a significant role in wind erosion, which are affected of lithology features, sedimentary environment, length and duration of transport, The average energy of transport, the nature and amount of weathering after deposition, and the duration of its transport. In this study, the status of Sphericity and roundness of Surface pavement particles were investigated in three types of pediment in Yazd-Ardakan plain. First, samples of surface pavement particles were collected randomly, Then, sphericity and roundness indices were calculated in each of the removed particles (320 particles). Powers Index was used in this research for sphericity and roundness, whose range varies from 0.12 for very-angular particles to 1 for well-rounded particles. The results of one-way analysis of variance between the obtained values indicated that there is a significant difference between the amounts of roundness in different types of pediments with 95% confidence level, but the sphericity rate is not significant. The results of grouping using Duncan test also indicated that roundness values can be analyzed in three separate groups, that these three groups consistent to the three types of pediments. The average values of roundness are equal to 0.18 in the erosion pediment, 0.30 in the appendage pediment, and 0.33 in the covered pediment, which indicates that particles in the covered pediment have more roundness but the roundness values in different types of pediments do not have a clear trend.