A Study on the Spatio-Temporal Variations in the Coastal Regions of Funafuti, Tuvalu

Island nations face heightened vulnerability due to the dynamic changes in their coastal regions, driven by both natural processes and human activities. Monitoring these changes over time is essential for understanding and mitigating their impacts. In this study, Funafuti Atoll, characterized by its small, scattered islets with unique features, was chosen as the study area. The research aims to assess recent coastal changes in Funafuti using Sentinel-2 satellite imagery, digital elevation model (DEM) data and sea level information. To extract the coastline, a semi-automatic approach combining segmentation and thresholding is applied to the normalized difference vegetation index (NDVI) image. Due to the unique characteristics of each islet, adaptive thresholding is employed to distinguish land from water effectively and thus, coastline from 2019 to 2023 is extracted. This study depicts the recent trends and short-term coastal alterations in Funafuti. Between the years 2019 and 2023, the coastline length and land area showed a net 2.9% and 7.3% decrease, respectively. The Fongafale (4.3%) islet showed a minor increase in coastline length. Furthermore, sea level and DEM data will be used to conduct Funafuti's volumetric change analysis.