Pluvial Flood Risk at Auckland Coastal Settlements

Many low lying coastal settlements and cities in New Zealand have ever increasing risk from rising sea level and precipitation due to climate change. Even if buildings and infrastructure are well above predicted sea inundation levels they are often still at risk of pluvial flooding due to ever rising tidal boundary conditions.

How should this risk be managed? What are the implications for stormwater infrastructure investment? What options are left when run-off meets high tide in low lying areas?

This paper explores the increasing demand on coastal outlets and low lying reticulation against a backdrop of high growth pressures in Auckland. It presents what we know about joint probability of rainfall and sea level to inform appropriate design standards for coastal infrastructure. For example what level of pluvial flood protection can be achieved and afforded in fully urbanised coastal areas?

Understanding of joint probability of rainfall and sea level is the key to informing affordable design parameters in such areas.