Assessment of wave climate change and its impact on littoral drift along the Kalutara and Kalpitiya beaches in Sri Lanka

Abstract

Natural and anthropogenic activities have accelerated the coastal erosion in Sri Lanka by threatening the economic developments and livelihoods in coastal zones. However, there is a limited number of studies on coastal erosion in Sri Lanka due to the lack of observed wave climate data around the island. This study identified the impact of wave climate changes on the littoral drift of seven selected locations in Sri Lanka. The reanalyzed wave climate data were used to estimate sediment transport rate in seven locations using empirical methods. The chronological volumetric changes of Kalutara and Kalpitiya beach volume were estimated, as those beaches experienced severe morphological changes during the above period. The relationship among the capacity of coastal sediment transportation of littoral drift, actual sediment accretion (and erosion), and shoreline management activities was critically discussed by collecting data from diverse sources to its fullest extent. The wave climate becomes rough on the western and southern coasts during the southwest monsoon and the eastern coast during the northeast monsoon. The average wave direction periodically changes on the southwest coast, and thus, the littoral drift occurs southwards at the Kalutara coast. The Kalpitiya areas were the main sediment accretion areas, but the Kalplitiya peninsula is slowly eroding with the recently intensified wave climate. Coastal erosion is an integrated effect of shoreline management, wave climate change, and reduction of river sediment supply. Therefore, coastal erosion should be studied with accurate numerical and physical model studies for the betterment of erosion management.

Analysis of shoreline changes in the severe storm surge region of upper Coromandel coast, India, using Remote sensing (RS) and Geographic information system (GIS)

“…The accumulation of sediment in a curved pattern in this region leads to the development of a beach. The littoral drift during the southwest monsoon is responsible for the movement and deposition of sediments, leading to the coastline's advancement in this area due to accretion (Samarasekara et al, 2023). Sediment movement down the coast, maybe pushed by cyclone waves, is called longshore drift.…”