Simulating the Impacts of an Applied Dynamic Adaptive Pathways Plan Using an Agent-Based Model: A Tauranga City, New Zealand, Case Study

Abstract

Climate change and relative sea-level rise (RSLR) will increasingly expose coastal cities to coastal flooding, erosion, rainfall and river-induced flooding, episodic storm-tide flooding and eventually, permanent inundation. Tools are needed to support adaptive management approaches that allow society to adapt incrementally by making decisions now without compromising decision-making options in the future.

We developed a model that integrates climate-related physical hazard and socio-economic drivers and used it to explore potential adaptation pathways. We examined how adaptive actions might be sequentially triggered within a low-elevation coastal city in New Zealand, in response to various climate change and socio-economic scenarios.

We found that different adaptive actions are triggered at about the same RSLR level regardless of the scenario and that the timing of actions within each pathway is dictated mainly by the rate of RSLR and the timing and severity of storm events. For the representative study site, the model suggests that the limits for soft and hard protection will occur around 30 cm RSLR, fully-pumped water systems are viable to around 35 cm RSLR and infrastructure upgrades and policy mechanisms are feasible until between 40 cm and 75 cm RSLR. After 75 cm RSLR, active retreat is the only remaining adaptation pathway.