Abstract
In case of oil spill, gravel beaches are hard place for recovery works. In this study, relations between shape of gravel and residence time of oil after Nakhodka oil spill accident has been examined based on the on-site surveys. Digital camera was used to take projected shapes of the gravel, and then public domain software "ImageJ" and spreadsheet have been used to analyze the shapes. Every taken image was transformed to 720-angled polygon in accordance with the coordinates of circumference to measure its angularity indices. The indices have been analyzed by 1) ratio between projected area and circumference, 2) difference of the radius between actually measured length of circumference and smoothly translated circumference, and 3) bending angles of the circumference. As a result, strong correlation coefficient (R2=0.858) has been occurred between angularity index obtained from bending angles and period of oil residue.
