Land raising as a solution to sea-level rise: An analysis of coastal flooding on an artificial island in the Maldives

Abstract

The Maldives (land elevation approximately 1 m above mean sea level) is often associated with the threat of rising sea levels. Land scarcity due to population pressure is also a major issue. In the late 1990s a new 1.9km2 1.8 m high artificial island, Hulhumalé was created for urban expansion, including an allowance for sea-level rise. This paper assesses flood exposure through an extreme water level scenario on Hulhumalé taking into account sea-level rise and analyses potential adaptation options to extend island life. Results indicate that overtopping is likely to occur with 0.6 ± 0.2 m of sea-level rise, with more severe, widespread flooding with 0.9 ± 0.2 m of sea-level rise. If the Paris Agreement goals are met, flooding is not anticipated this century. However, under a non-mitigation scenario, flooding could occur by the 2090s. Building seawalls 0.5, 1.0, and 1.5 m high could delay flooding for 0.2, 0.4, and 0.6 m of sea-level rise, respectively. Land raising has been successful in Hulhumalé in reducing flood risk simultaneous to addressing development needs. Whilst new land claim and raising can be cost-effective, raising developed land provides greater challenges, such as timeliness with respect to infrastructure design lives or financial costs. Thus the transferability and long-term benefits of land raising requires further consideration.