Offshore artificial islands and shoreline change in Southern Hainan Island: Development and challenges

Abstract

Intensifying coastal development has significantly altered shoreline dynamics, highlighting the urgent need to comprehend the intricate change processes and impact mechanisms involved. This study examines the multifaceted influences of four offshore artificial islands as well as other coastal engineering projects on shoreline dynamics in southern Hainan Island, China. It employs a transect-focused approach, integrating 864 Landsat and Sentinel images from 1986 to 2023 and statistical techniques. The precision of annual shoreline position derived from satellite images improved to 0.7–1.2 m. The shoreline changes were categorized into stable (8 %), eroding (36 %), and artificially altered (56 %). The study reveals that offshore artificial islands can effectively protect the shorelines they directly face from erosion and foster accretion, but also cause erosion on adjacent shorelines and significantly change the coastal landscape, leading to complex environmental outcomes. The findings underscore the dual nature of offshore artificial islands' impact on coastal environments, emphasizing the importance of sustainable coastal engineering and the need for thorough environmental assessments to avoid or mitigate potential negative effects on shoreline stability and landscapes, particularly in tourist cities known for their fine sandy beaches and picturesque coastal scenery, such as Sanya City.