28 Sep 2026
New Zealand's incoming El Niño climate cycle is set to test the resilience of our communities and infrastructure. While eastern and northern regions face the prospect of prolonged dry conditions and growing water scarcity, western and southern areas are likely to experience more intense rainfall events, flash flooding and rising urban heat impacts.
This contradiction in weather patterns requires dual-purpose on-site infrastructure capable of both attenuation during peak rainfall and boosting water supply when it's dry.
Decentralised water capture and retention
As you know, traditional stormwater systems are designed to push rainwater away from properties as fast as possible. However during volatile El Niño weather, this approach backfires. It worsens dry, cracked soils during droughts and overwhelms public drainage systems during sudden, heavy storms.
Using localised water retention systems such as slimline tanks against building walls or hidden under-slab storage (like Aquacomb) helps properties rely less on public water networks.
These systems do two important jobs –
- They store non-potable water for dry periods.
- They slow down peak water flow during heavy downpours to protect local drainage networks.
Protecting property when it floods
In contrast, flash floods caused by sudden heavy rain require reliable ways to immediately protect buildings and infrastructure.
For commercial or unattended properties, fixed passive flood barriers detect incoming water flow to deploy automatically, removing the need for manual setup.
Portable barriers (like Floody) offer flexible protection for doorways, driveways, and underground entrances, letting facility teams or property owners quickly seal off high-risk areas as a storm approaches.
Mitigating urban heat islands
Long El Niño heatwaves cause cities and buildings to trap and redirect heat. Standard asphalt and concrete act like heat sponges, blocking moisture from soaking into the ground and stopping the natural cooling effect of evaporating water.
Replacing traditional paving with high-void systems changes how surfaces handle heat. Lighter materials reflect more sunlight and absorb less heat overall.
Permeable paving (such as Porous Lane) lets air and rainwater soak deep into the ground. When temperatures rise, trapped moisture evaporates upward through the material, creating a natural cooling effect.
Instead of sending rainwater down public drains, permeable surfaces guide water straight into the soil. This keeps tree roots and urban greenery hydrated, preserving the shady canopy needed to cool cities and preventing dry soils from worsening urban heat.
Complete system design
By pairing on-site water storage and flood barriers with permeable paving, engineers can protect properties against droughts, flash floods, and severe heat to help combat the issues brought by our ever-changing climate.
Watersmart offers a free design service to help you navigate both the wet and the dry challenges that El Niño will bring.
This article was supplied by WaterSmart, one of our partners. While we are pleased to share insights from our partners, Engineering New Zealand does not verify all claims and does not endorse specific products or services.
