Numerical analysis of wave climate driven variations in longshore sediment transport along Mahabalipuram coast, Southeast coast of India

Abstract

The study examines the impact of wave climate change on the longshore sediment transport rate (LSTR) along Mahabalipuram (a UNESCO World Heritage Site) on the east coast of India. Wave climate changes and LSTR were evaluated using a spectral wave module (MIKE 21 SW) and LITPACK (1951–2020). The hourly integral wave parameters (significant wave height (Hs), peak wave period (Tp), and mean wave direction (Dm)) computed at the study location were used to estimate net and gross LSTR. The average Hs, Tp, and Dm were 0.85 m, 7.34 s, and 118° (E-SE), respectively, resulting in an average net northerly transport of about 0.046 × 106 m3/year, and gross transport of 0.2 × 106 m3/year. It has been shown that the changes in the LSTR are primarily associated with the LST of the seasonal variations that correspond to the seasonal changes in the wave climate. An overall increasing trend in wave climate (0.001 m/yr), net (∼ 320 m3/yr), and gross (∼ 619 m3/yr) LSTR was observed. The gross LSTR showed an increasing trend of about 17.6 % (1951–2020).The net LSTR is northward, except for a few years when the direction of net LST reversed. Understanding the variability in longshore sediment transport at the seasonal, inter-annual, and decadal scales is vital for designing better management plans for a coast.