Seasonal variability on cross-shore profile in meso-tidal settings due to lunar cycle effects in Kuala Terengganu Coast

Abstract

Kuala Terengganu, one of the coastal zones in Malaysia, is prone to natural hazard factors, such as coastal erosion. The impacts of coastal erosion alternate the morphological structure of the beach in Terengganu. The beach morphological changes were driven by the seasonal monsoon such as Northeast Monsoon (NEM) and Southwest Monsoon (SWM) season. Hence, to understand the short-temporal morphological response of meso-tidal beaches during spring tide events throughout the lunar cycle phase, the study was investigated in Batu Buruk beach, Kuala Terengganu. The tidal cycles, particularly during spring tide (Full Moon and New Moon phases) were collected from five transects starting on October 2020 to October 2021. The monitoring of cross-shore was conducted by using RTK to measure the cross-sectional area and sediment volume changes. The data collected were computed by using profiler 3.2XL software. Numerical modelling such as MIKE-21 was used to simulate tidal elevation within the period of this study. The study showed significant impact by the lunar cycle on sediment gain and loss. The cross-sectional analysis revealed positive sediment gains during the Full Moon. However, the New Moon erosion seemed to take place around the upper swash zone area. This provides an insight into the spring tide and contributes to beach recovery processes.