Climate Change

In March 2026, ŌHRN published a report about what climate change might mean for the Ōpāwaho Heathcote River and its catchment.

The report that lays out the possible climate scenario outcomes for the Ōpāwaho Heathcote River catchment in a factual, non-alarmist manner while being mindful of the constantly changing understandings that underpin climate change knowledge.

The report, Under Pressure: Climate Change and the Ōpāwaho Heathcote River Catchment, is available online here.

What follows below is a synthesis of the main findings of the report as they directly affect the river and its catchment followed by some practical guidance that relates to the findings.

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What climate change means for our river and its catchment

• Our river is already under pressure from years of urban development, runoff from the Port Hills, and pollution. Climate change adds a new layer of pressure.
• Hotter days, fewer frosts, and changing rainfall: More hot days (25°C +) and fewer frosts will bring longer summers and warmer spring and autumn periods. These shifts may place more heat stress on the river. At the same time, drier winters will dry out soils more, and heavier summer rain is likely to increase runoff and localised flooding.
• Heavier downpours and higher flood risk: Summer storms are expected to become more intense, which may make flash flooding more likely, especially in areas already prone to flooding.

• Sea level rise and land subsidence: Because land around Ferrymead is gradually subsiding, the effects of sea-level rise may become noticeable there sooner than other areas, with gradual impacts extending further upstream over time
• Impacts on ecosystems: Warmer water, changing flows, erosion, and more frequent algal blooms will place taonga species like tuna, lamprey, īnanga and kōura under increasing stress.
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  The Cashmere Valley detention wetlands and dam in February, 2026. Alden Williams, The Press

  Increasing wildfire risk: Hotter, drier conditions and stronger seasonal winds are expected to increase the likelihood and severity of wildfires on the Port Hills.

How we can adapt as a community

• Be part of planning the future of the catchment: Christchurch City Council and Environment Canterbury will be developing adaptation plans for the catchment. Your voice matters when decisions about land use, flood management, and restoring the river are made.
• Make room for the river: Advocate for new stormwater basins, restored wetlands, expanded riverside green spaces, and protection of higher-risk areas from further development.
• Join local restoration efforts: Groups like the Ōpāwaho Heathcote River Network and neighbourhood volunteers are already planting, weeding, monitoring water quality, and caring for the river.

Practical steps for households

• Learn your property’s flood or stormwater risk: Use CCC’s climate hazard viewer and the Climate Adaptation Toolkit to understand your property’s exposure and find practical ideas for your situation.
• Reduce runoff from your place: Small changes help: install a rainwater tank, use permeable surfaces instead of concrete, and create rain gardens or dense planting along fences.
• Plant for the future: Choose hardy natives that cope well with heat and dry spells. Trees help cool neighbourhoods, absorb stormwater, and support river health.
• Keep contaminants out of drains: Everything on your section eventually reaches the Ōpāwaho: wash cars on grass, fix oil leaks, use less fertiliser and herbicide, and sweep hard surfaces instead of hosing.
• Prepare for hotter summers: Use shade, ventilation, and trees on the north and west side of your home to keep indoor temperatures down — especially important for children, older people, and pets.
• Prepare for extreme weather: Use the CCC Be Ready resource to help you to prepare your home for more extreme weather events.