Adaptation benefits and costs of raising coastal buildings under storm-tide inundation in South East Queensland, Australia

Pathways of adapting the built assets for future risk reduction are highly uncertain because of changes in socio-economic trends and climate. To provide solid foundation for better adaptation planning, this paper presents a statistical approach to investigate the future direct damage loss and the benefit of adaptation through elevating building floors of residential and commercial buildings affected by storm-tide hazard and sea-level rise in South East Queensland, Australia, particularly the implication of different extents of adaptation to policies. Because of projected socio-economic growth, it was found that, if considered separately, building stock growth causes twice as large as sea-level rise does to the potential damage loss. Adaptation by elevating new buildings alone is more cost-effective and socially acceptable than by elevating both new and old buildings. It is concluded that even with limited adaptation, immediate but less long-term net benefits could be achieved by focusing adaptation on the most vulnerable coastal housing. Somewhat pre-emptive adaptation that lifts more coastal housing in wider coastal area in the immediate term to accommodate future storm tides gives longer-term net benefits, though incurs higher adaptation costs. However, too much over-adapting may be undesirable as it incurs unreasonably high initial and on-going costs while the benefits of it could only be reaped over unrealistically long time. Geographical extent of asset adaptation should be decided in accordance with the planning time horizon to avoid either under- or over-adaptation.