Adapting ports to sea-level rise: empirical lessons based on land subsidence in Indonesia and Japan

Five cases of ports in Japan and Indonesia that have subsided by a metre or more were analysed. The findings suggest that there are no unsurmountable technological, cost-benefit, financial and social limits to the progressive raising of these ports, at least for the magnitude of climate-induced sea-level rise expected during the 21^st century. In Indonesia observed adaptation is a sequential process: only part of the port is raised at one time, allowing port operations to continue elsewhere and spreading costs in time. Jumps in unit costs are apparent as the elevation height increases. In addition, the possibility of sea-level rise triggering innovative changes in port design to lower costs (e.g., a move to floating ports) is being considered. For traditional ports to upgrade by up to 1 metre, unit costs are found to be somewhere between 50–360 USD/m³ rise (not including the cost of piling). Nevertheless, such adaptation costs would represent a significant burden and adaptation is often reactive rather than proactive, leading to significant damage costs, as in the case of Hurricane Katrina’s impact on Gulf Coast Ports.