Textural and depositional processes of surface sediments of Kalpakkam, Southeast Coast of India

To understand the influence of human disturbance on the sediment processes along Kalpakkam coast, India, beach and seabed sediments at 200 m, 500 m, and 1 km into the sea were collected monthly for one year and analyzed. Coarser material close to the tidal inlets (river) and manmade structures (sea wall) indicate the effect of these features in altering the grain size distribution from the general trend. The bivariant plots confirm the dominance of deposition under beach environment. The CM diagram (C — one percentile grain diameter, M — median) divulges that the deposition takes place by suspension and rolling of sediments with C < 1 mm. Linear discriminate function analysis for sediments at Kalpakkam indicates a shallow marine environment for all the samples collected. On the multigroup multivariant discriminant functions V1-V2 diagram, the bulk of the samples from Kalpakkam to Mahabalipuram fall in the field of beach deposition. These results show that reworked sediments, submerged during the Holocene marine transgression are being deposited on present-day beaches by waves, currents and rivers in the study area. Though a high wave energy environment is prevailing in the study area, dominant northward sediment transport along the Kalpakkam-Mahabalipuram coast is not altered due to human interventions. Beach building activity in front of the sea wall ensures the safety of Indira Gandhi Centre for Atomic Research (IGCAR) from wave actions without causing any significant changes to the coastal environment.