A warmer atmosphere holds more water vapour and can absorb more water from the ocean and land. We can expect heavier rainfall over time, increasing the risk of flooding and erosion.

Expected impacts 

Christchurch typically gets around seven very rainy days each year, where the rainfall is more than 25mm. In our district, the number of rainy days may not change, but we’re expecting more intense and heavier rain.  

We’re also expecting seasonal changes in heavy rain. Winters could be wetter, with between 15 to 40 per cent more rain. 

Christchurch has many low-lying areas which have always been prone to flooding during heavy rain. It’s normal for some streets to be temporarily flooded during rain, as they form part of our stormwater system. But if flooding is extreme, threatens property or stays around, please contact the Council using Snap Send Solve.

What this means 

  • Rivers and streams could flood more often and to higher levels, impacting people, property, infrastructure such as roads and bridges, businesses, crops, livestock, cultural values and mahinga kai (food gathering).
  • Heavier rainfall can trigger landslides and increase soil erosion, affecting properties, access, landscapes and the health of waterways and coastal ecosystems.  
  • More frequent surface flooding can cause issues for low-lying properties and limit access along some roads.  
  • Insurance costs for homes and businesses may increase or become unavailable in areas most at risk.  
  • Council parks and sports grounds may be affected by flooding or be too wet for use over winter.
  • Increased erosion can lead to more sediment in waterways, gradually reducing stream capacity and increasing flood risks.  
  • Indigenous plants and animals may be exposed to flood impacts, landslides and erosion.  

What you can do

  • Avoid living, building or investing in areas highly prone to flooding. To understand flooding risks in Christchurch, see our floor level map(external link).  
  • Keep gutters, downpipes and roadside drains clear of leaves and debris, to allow water to drain freely. Report any drainage issues on the street to the Council through Snap Send Solve(external link).
  • Landscaping should direct water away from your home and allow rainwater to naturally drain into the soil through gardens, grass or permeable surfaces. Avoid large areas of concrete or asphalt which can exacerbate flooding.
  • Assess your home for flood risks and take precautions to minimise damage, such as storing valuables and important documents in high places or raising up electrical equipment such as outdoor heat-pump units. Elevate any chemicals, such as garden sprays, paint, fuel or oil, to prevent contaminating floodwaters.
  • Stay informed about rain forecasts and weather warnings to act early. This may involve moving your car to higher ground and ensuring whānau (family) don’t sleep in flood-prone locations like garages or sleepouts. Check the latest updates on MetService, radio or TV.

What we’re doing  

  • Flood prevention and stormwater management – We maintain and improve our stormwater systems to make the city a safer and healthier place to live. Our extensive stormwater network includes open drains, pipes, pump stations, stop banks and water detention basins, to help prevent flooding. We also require many new developments to manage their stormwater on-site to limit flooding downstream. Learn more about our flood prevention(external link).
  • Managing development in vulnerable locations – We require buildings to be above 1-in-50-year flood levels and have planning rules and regulations for development in areas vulnerable to less frequent, but larger and more potentially damaging, floods which could cause a risk to property or life. Learn more about the Christchurch District Plan(external link) and floor level map(external link).  
  • Enhancing our waterways and wetlands – We maintain and improve our network of waterways and wetlands to enhance our ability to manage floods, reduce soil erosion and improve the health of our rivers and streams. Learn more about how we're enhancing our waterways(external link).  
  • Partnering with community groups to restore waterways – We’re partnering with community groups and landowners to help care for, and improve, our network of waterways and wetlands in Christchurch and Banks Peninsula. Learn more about our Community Waterways Partnership(external link).
  • Regeneration of the Ōtākaro Avon River Corridor – We’re restoring the Avon River Corridor to improve our ability to manage floods and sea-level rise. Around 15 stormwater treatment areas will collect and clean about one-third of the city’s run-off before it enters the river. Learn more about the Ōtākaro Avon River Corridor.