Cumulative Land Subsidence in Populated Asian Coastal Cities

Abstract

In contrast to sea-level rise, which is often associated with climatic and environmental changes, land subsidence has largely been overlooked in discussions regarding future adaptation to higher sea water levels. In order to articulate the critical contribution of this phenomenon, this short paper provides a reliable chart that details land subsidence in densely populated East and Southeast Asian coastal cities. The causes of subsidence at these locations are also discussed based on existing literature. Land subsidence was observed to be one or two orders of magnitude faster than sea-level rise caused by an anthropogenic global warming, and can continue unabated unless its root causes are addressed through clear policies at the municipal level. Subsidence is clearly a localized problem, and is thus easily overlooked by regional or national governments. Nevertheless, once subsidence takes place it cannot be reversed, and hence it is crucial to rapidly formulate appropriate countermeasures when it is identified. The examples of these Asian cities demonstrate that, if subsidence is recognized and adequate policies are put in place and implemented, it can be brought under control in a fairly short period of time.