Hydrostatic sea-level rise inundation impacts on ahu and harbors of Rapa Nui (Easter Island)

Sea-level rise (SLR) threatens coastal communities, infrastructure, and cultural heritage worldwide, with small islands among the most vulnerable. Rapa Nui, renowned for its ahu and approximately 1,000 moai statues, faces dual risks: damage to irreplaceable cultural sites and disruption of modern harbors, both fundamental for maintaining cultural continuity and sustaining the island’s economy. This study evaluates the impacts of SLR on Rapa Nui’s coastal heritage and infrastructure using a probability-based hydrostatic inundation model. We establish present-day mean higher high water (MHHW) and the 1% annual exceedance probability (AEP) water level as reference baselines and simulate inundation extents at incremental SLR scenarios up to 3.9 m. Results indicate that four ahu are already impacted by present-day sea levels, and eight more are projected to be impacted by 2080. In the same timeframe, harbors are projected to be fully submerged under MHHW conditions. Comparisons between observed and modeled impacts further suggest that hydrostatic modeling inherently underestimates risk in Rapa Nui’s high-energy coastal environment. These results underscore the need for proactive adaptation strategies that integrate cultural heritage preservation with coastal resilience planning and improved hydrodynamic modeling to safeguard Rapa Nui’s identity, economy, and long-term sustainability.