Abstract
Rising sea level is generally assumed and widely reported to be the significant driver of coastal erosion of most low-lying sandy beaches globally. However, there is limited data-driven evidence of this relationship due to the challenges in quantifying shoreline dynamics at the same temporal scale as sea-level records. Using a Google Earth Engine (GEE)-enabled Python toolkit, this study conducted shoreline dynamic analysis using high-frequency data sampling to analyze the impact of sea-level rise on the Malaysian coastline between 1993 and 2019. Instantaneous shorelines were extracted from a test site on Teluk Nipah Island and 21 tide gauge sites from the combined Landsat 5–8 and Sentinel 2 images using an automated shoreline-detection method, which was based on supervised image classification and sub-pixel border segmentation. The results indicated that rising sea level is contributing to shoreline erosion in the study area, but is not the only driver of shoreline displacement. The impacts of high population density, anthropogenic activities, and longshore sediment transportation on shoreline displacement were observed in some of the beaches. The conclusions of this study highlight that the synergistic use of multi-sensor remote-sensing data improves temporal resolution of shoreline detection, removes short-term variability, and reduces uncertainties in satellite-derived shoreline analysis compared to the low-frequency sampling approach.
Highlights
Coastal cities are spread around different regions of the world, with more than two-thirds of the global population living within 100 km of the sea [1,2]
By ensuring that shorelines were extracted for almost every month of the study period, the impact of sea-level rise on shoreline displacement could be estimated
Sea-level change is usually perceived to be responsible for long-term shoreline displacement, but our study showed that both erosion and accretion occurred along the shoreline, whereas there was a consistent rise in sea level at all stations along the Malaysian coastline
Summary
Coastal cities are spread around different regions of the world, with more than two-thirds of the global population living within 100 km of the sea [1,2]. Coastal areas are essential regions of socio-economic and environmental benefits [3], densely populated, and highly urbanized, and are usually highly morpho-dynamic [4]. The shoreline, an intersection of the marine environment and the mobile coastal system, is one of the most dynamic features of coasts [3]. About 31% of the 1.63 million km of world coastlines are sandy coasts that are highly susceptible to rapid advances/retreats and long-term accretion/erosion due to changing environmental conditions and coastal processes [2]. Techniques that couple physical landscape processes associated with climate change with human behavior have been employed in many coastal susceptible and vulnerability assessment studies [5]. Assessing the causes of coastal vulnerability, especially shoreline erosion and coastal flooding, is a difficult task due to the complexity of the processes acting at varying spatial and temporal
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