LiDAR-based SedNetNZ model predictions of net sediment yield from surface erosion in the Napier area. Green and yellow colours show more sediment yield.
It was first applied in the Manawatū catchment in 2013 as part of the Clean Water Productive Land research programme. Since then it’s been taken up by nine of Aotearoa New Zealand (AoNZ)’s 11 regional councils, whose land and water managers find it invaluable to model sediment loads, to calculate reductions in load required to reach freshwater targets, and to set freshwater objectives.
Senior Researcher Dr Hugh Smith says that over time SedNetNZ has undergone several updates, including improvements to better represent processes such as riverbank erosion. New modelling functions have also been added to estimate the potential effects of climate change on erosion rates and sediment loads under different policy scenarios.
The focus of this work has been consistently on developing data-driven modelling approaches to support better targeting of erosion control at the regional, catchment and farm scales.
With regional LiDAR data now widely available in New Zealand, a new, high-resolution LiDAR-based version of SedNetNZ was completed in June 2024. This updated version was first applied in the Hawke’s Bay region as part of a partnership project with the Hawke’s Bay Regional Council.
Incorporation of the LiDAR data has allowed improved erosion and sediment model parameterisation and predictive performance, because it gives a much more accurate representation of topographical features such as slope angle and curvature, as well as better representation of the stream network itself including stream channel shape, slope and bank height.
The upgraded version of SedNetNZ can also produce higher resolution layers for selected erosion processes – for example, showing at a finer scale than previously possible which areas of land are most susceptible to shallow landslides. This information can then be used by land managers to better target tree planting in areas of pastoral land most affected by slope instability.
Recognising its use in supporting better land and water planning, the upgraded LiDAR-based model is now being applied in a project with Waikato Regional Council.
For more information, including how to upgrade SedNetNZ to the latest LiDAR version, contact the core development team: Dr Hugh Smith, Dr Andrew Neverman and Dr Simon Vale.
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