Variability of the local wave regime and the wave-induced sediment transport along the Ganpatipule coast, eastern Arabian Sea

Abstract

For planning coastal protection measures, information on nearshore waves and the wave-induced sediment transport rates are required. This study examines wave-induced longshore sediment transport (LST) rate considering three widely used bulk transport formulae using measured wave data at 14-m water depth covering six years (2011-2016). The study shows that selection of appropriate formulae for estimation of LST rate is important since the estimates based on different formulae vary from 4-5times larger as compared with Kamphuis equation, which is a reliable formula for estimating LST rates across the eastern Arabian Sea. Meridionally oriented coast presents a predominant north to south LST regime as a result of the wave climate, where the lowest values of significant wave heights (Hs) occur during October-April (< 1.5 m) and highest energy conditions occur in the Indian summer monsoon (June-September) when Hs exceed 2 m. Sedimentary dynamics during the monsoon contributes to 77%-88% of the annual LST due to the high wave energy present during this period. Even though the inter-annual variation in annual mean Hs is 6%, the variations in gross LST is up to 22%. The study shows that a small error (?1-5�) in the estimation of the wave breaker angle leads to a significant error (10%-90%) in the LST rate. Also, 5%-20% error in the wave height leads to 7%-43% error in the annual LST rate.