ACCURACY OF AUTOMATED GRAIN SIZING (AGS) AT DIFFERENT GROUND SAMPLING DISTANCE

Abstract

Automated grain sizing technique (AGS) has been widely used to characterize the grain size distributionof particles at channel bed. Although a number of techniques were available as described in the literature, the accuracy of this technique was subject to further validation and verification. The accuracy of AGS technique is hindered due to over-segmentation and pixel resolution of the imaging samples. Another disadvantage / drawback is the distance between pixel centers measured on the ground. This paper 
discusses the grain size distribution (GSD) using AGS technique taken at different ground sampling distances. The GSD curve from AGS technique was fitted to the conventional curve obtained by sieving and correction factors were proposed to reduce errors between these two techniques. It was observed that different ground sampling distance did not affect the GSD. However, GSD using AGS and conventional sieving showed some variation due to over-segmentation. The use of correction factors gave better results and it was nearly unity between two techniques.

Keywords: Automated Grain Sizing, Grain Size Distribution, Sieving, River Bed, Bed Material, Correction Factor