The Effects of Climate Change on New Zealand's Stormwater and Wastewater Systems

We know climate change is happening and we know our stormwater and wastewater systems are particularly vulnerable. A recent example is the Edgecumbe floods, where raw sewage floated through the streets, making the clean-up a near-impossible mission. Six months later, 500 houses are still unliveable and flood-proofing the town remains a distant goal.

The asset value of stormwater and wastewater assets in New Zealand is well over $20 billion. This includes 24,000 kilometres of public wastewater network with more than 3,000 pump stations, and over 17,000 kilometres of stormwater network. Much of it however, is poorly designed for the challenges climate change will bring, from sea level rise to the predicted changes in precipitation frequency and intensity. We are yet to truly understand how the impact of climate change will unfold in different regions, specific locations, and over varying timescales. This makes it difficult to know how best to adapt.

Early in 2017, the Deep South National Science Challenge Impacts and Implications Programme brought experts together to discuss the challenges and concerns for the sector in Aotearoa New Zealand. Participants included academics and scientists; industry groups and and government policy analysts; water service providers and consultants. This discussion resulted in a paper, co-authored by participants in that dialogue. Insights from this paper will be discussed in this session and will outline our current knowledge and the priority areas of research needed to prepare our stormwater and wastewater systems for a changing climate.