A wealth of land information is poised to be unlocked online, thanks to an extensive LiDAR mapping project being run by Land Information New Zealand (LINZ) in partnership with local government councils.
LiDAR (light detection and ranging) is a well-established distance measuring system employing lasers to send “pulses” of light out, measuring the time for the signal to return, and creating images of the land from the data.
The technology has existed for 50 years and came to public attention in 1971 when used to map the surface of the moon on the Apollo 15 mission.
The sub-metre accuracy of the technology provides invaluable information on land’s hydrology, slope and erosion, far exceeding the existing topographical 20-metre contour maps so familiar to trampers.
LINZ national elevation programme manager Bjorn Johns says the project aims to have 80% of the country mapped by 2024, with 20% of the country already covered.
The project was initiated and funded through a $19 million Provincial Growth Fund grant.
“The project aims to not only map the entire country, but to make high-quality mapping data openly available to those that need it in a consistent format through the online LINZ Data Service,” Johns said.
Compared to earlier national mapping data with its 20m contour gaps, the LiDAR data will offer farmers the opportunity to have specific, validated maps included within farm environment plans (FEPs) that can highlight risk areas for erosion, flooding and run-off.
Having highly accurate contour information will also help at a management level by enabling better prediction of fertiliser application depending upon slope, and for modelling changes from existing to future land-uses.
Regional councils are aiming to push out a large range of extended map features including waterway mapping, slope classes to identify slope related risks on farms and better models on coastal inundation, river flooding risks and erosion.
Johns says interest has also been strong from the forestry sector.
Foresters see the technology helping them get better information about terrain, reducing costs for planning and infrastructure, and making forest feasibility studies more accurate.
They are also better able to make more cost-effective estimations for plantation volumes, knowing the contour of the land below the planted trees, ensuring better targeting of pruning and improved productivity.
Improved predictions for soil erosion and sedimentation risk also mean mitigation costs and environmental impacts can be reduced.
Anyone with skills to access and operate mapping software can create map imagery from the online data.
“One of the most powerful aspects of the data is that it puts both landowner and regional authorities on the same page for highly accurate information,” he said.
“The farmer does not necessarily have to now bring a surveyor onto the property to get a map done.”
The data is being captured through a squadron of aerial surveyors contracted by local councils, and data collection is already completed for Northland, Gisborne, Hawke’s Bay and much of Waikato.
Collection is done of the “bare earth” ground and of the “highest feature” surface, which includes buildings and vegetation.
While different in execution to hyperspectral mapping, also being employed by some agencies around New Zealand, LiDAR sits alongside it.
Combining the two technologies can deliver imagery that not only identifies the land’s characteristics, but the type of vegetation and soil types that lie on and within it.
As the LiDAR data is collected via aerial survey it is being loaded into LINZ’s online site for access, and the agency is hoping to build a series of case studies on the use of the data in real farm, forest and council situations.
Johns says while the technology is well established, the project’s full success will come from new users beyond the traditional engineering and council professions being aware of its presence and utilising it to its full potential in other areas.
