Dr Clint Rissman is a water scientist whose company is updating Southland’s soil maps with new technologies which are correcting many of the maps made in the 1990s and early 2000s.
Advancing science is leading to much more detailed soil maps and new technologies are correcting Southland’s decades old soil maps, an expert says.
Dr Clint Rissman is adjunct to the University of Canterbury and Lincoln University, and director of Invercargill-based environmental consultants Land & Water Science.
The soil maps of the 1990s and early 2000s were being superseded by multiple types of higher resolution imaging, he said.
In some areas, the new data was a significant departure from the older maps, Rissman said.
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One farmer at the top of the Waituna catchment had their land re-consented, Rissman said. The old map said they were at high-risk for nitrate loss, but the farmer doubted that, and the new mapping backed that up.
Areas of peat were regularly being found using the newer technologies, and those areas were important for carbon storage, he said. Another find was a wetland near Edendale that the maps had never picked up.
The project has covered about a third of Southland’s productive land, as they have mapped the Mataura catchment.
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The next step was taking the new maps to the farms to be cross-referenced with the farmer’s valuable knowledge, and also to dig holes and confirm the imaging, Rissman said.
Rissman’s company also mapped east Otago, West Coast, Tasman and Malborough in an MPI funded project, and the Northern Wairoa River catchment in Northland for the Parliamentary Commissioner for the Environment.
Their work was not about bagging the previous mapmakers, he said, the technology had simply got better.
Soil maps were like the fundamental layer for environmental policy and rules, he said. The soil maps overlay the underground water and the soil on top determines if the underground water gets contaminated by nitrate.
Rissman and the fellow scientists use the European Space Agency satellite, airborne gamma ray spectroscopy and LIDAR.