Grain size distribution of the sediments along the Kollam shoreline, Southwest coast of India

This study investigates the sediment transportation and deposition in the Kollam shoreline, Southwest coast of Kerala, India. For this study forty-five (S1-S15) surface sediment samples were collected from five beaches in three different seasons. Results of sediment samples across three different seasons reveal significant temporal shifts in mean grain size (medium to coarse sand), sorting (poorly sorted sediments in monsoon), skewness (coarse to fine-skewed), and kurtosis (leptokurtic to platykurtic). Medium sand dominated sites S3, S4, S5, S6, S7, S11, and S13 throughout all seasons, while monsoon-driven hydrodynamic energy resulted in poor sorting and coarse sand deposition in S1 and S15. Skewness transitions highlighted fluctuating wave and riverine influences, with leptokurtic patterns were most prevalent in the pre-monsoon and post monsoon season, while mesokurtic patterns dominated in monsoon season. Linear Discriminant Function (LDF) analysis delineated depositional environments, indicating beach (100% in Y1) and shallow marine dominance (80% in Y2, 100% in Y3), with minor fluvial input during monsoon. Stewart and CM plots documented wave action as the primary sediment transport mechanism of graded suspension and rolling under high-energy monsoonal conditions. However fluvial processes were responsible for the deposits in S1 (Berm) and S15 (low tide line) during the monsoon.