Spatiotemporal analysis of shoreline change trends and adaptation in Bali Province, Indonesia

Abstract

Shoreline change is a dynamic and complex phenomenon influenced by various natural and anthropogenic factors. Monitoring these changes is crucial for understanding coastal dynamics, managing resources, and mitigating the impacts of coastal erosion and accretion. Remote sensing plays a vital role in monitoring shoreline change. This technology has emerged as a powerful tool for accessing and monitoring shoreline changes due to its ability to capture large-scale spatial data over different periods. This study investigated the dynamic changes in shoreline position in Bali Province from 2016 to 2021 using high-resolution PlanetScope imagery data. Multitemporal shorelines were extracted using the Normalized Difference Water Index (NDWI) to delineate seawater from distinct land-cover types. The end point rate (EPR) model was then used to statistically quantify the shoreline change rates. The results revealed variations in the positions of the shorelines throughout the study, with rapid erosion emerging as a major concern in Bali Province, primarily driven by human activities and/or coastal hydrodynamics. During the study period, the shoreline in Bali Province decreased from 668.64 km to 662.59 km at an average rate of -1.21 m/yr due to continuous erosion, with the most significant retreat occurring at Klungkung Regency. On the other hand, human-caused shoreline advancement, such as land reclamation, harbor, and airport construction, has resulted in a net land increase of 1.25 km2. The protection strategies include structural interventions such as breakwaters and seawalls. The finding provides valuable information that will be helpful for coastal planning and management to reduce the loss of the economy and safeguard the future coastal environment in Bali’s coastal areas.