Implication of shoreline and nearshore morphological changes on sediment budget of wave-dominated Chennai beach, India

Abstract

The study examines the shoreline (1990–2019) and nearshore morphological changes (seasonal) to understand the littoral drift and sediment budget variability. Shoreline change rate depicts erosion (− 0.06 m/year) in the northern sector and accretion (+ 0.12 m/year) in the southern sector. Seasonal nearshore morphological changes from non-monsoon to monsoon period signifies net erosion (− 1.8 × 104 m3) in northern sector and net accretion (+ 2.5 × 104 m3) in the southern sector. Although the lost sediment during monsoon is regained in non-monsoon period, the quantity of sediment gain is reduced in areas with human interventions. The results of the investigation depict the dominance of littoral drift towards north from February to October, when wave approach from east-southeast to south-southeast direction and southwards from November to January when the wave direction was from east-northeast to east-southeast. The net longshore sediment transport rate estimated during the study period was 2.6 × 105 m3/year in the northern sector and 1.5 × 105 m3/year in the southern sector with higher rate attributed to monsoon than the non-monsoon. Sediment budget results in deciphering the causes of erosion (− 1.27 × 104 m3/year) in northern sector and accretion (3.91 × 104 m3/year) in southern sector in the wave-dominated Chennai beach.