Helicopter flights to capture information on future peat soil subsidence are due to take place over the next month as part of a long-term Waikato Regional Council programme.

These helicopter flights represent the first round of region-wide peat subsidence monitoring, with the next round of flights to be in 2025.

The purpose of these flights is to collect ground surface level data using a technique called Lidar, as well as aerial photography.

Waikato Regional Council soil and land scientist Justin Wyatt said the Waikato region has 89,000ha of peat soils, with about 80 per cent drained for productive land uses.

“Peat drainage results in land subsidence and we need to understand and plan for the potential consequences of this ongoing subsidence,” Mr Wyatt said. “To better understand the potential impacts and to enable us to provide good advice for future land and drainage management of our peat soils, we need robust information on peat subsidence.”

So, with the support of Manaaki Whenua – Landcare Research, the University of Waikato and University of Canterbury, Waikato Regional Council has developed a long-term monitoring programme to capture peat subsidence information across the region.

“In time, this work will improve our understanding of how existing peat soil management influences subsidence rates and will provide information on how future changes in land management and other factors, such as climate change, will impact peat subsidence,” Mr Wyatt said.

The Waikato region has approximately 40 per cent of New Zealand’s peatland resource.

Drainage has allowed peat soils to contribute to the regional economy, but this results in subsidence and oxidation of the peat and ultimately the loss of the peat resource. Subsidence contributes to greenhouse gas emissions through carbon loss. It can also adversely affect adjacent infrastructure, such as roads, provision of services and impact on land drainage. In these situations, it is important that robust data supports planning to better manage and preserve these soils.

Mr Wyatt said there are 12 monitoring sites across the region where measurements will be captured. Landowners have been contacted directly via letter and may notice a helicopter flying in a regular pattern at an elevation of 153 metres above ground level over all or part of their property.

“Some of our monitoring transects include mineral, non-peat soils to help check the data we are collecting over peat soils. Monitoring locations were selected to ensure surveying covers a representative mix of land uses, peat type, peat depth and drainage types.”

The duration of survey flights will depend on the size of the monitoring area. Flights are dependent on weather conditions.

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