New Zealand's Marine Realm
NIWA has transformed 1.5 million square kilometres of data into the most accurate and detailed map yet of the land underneath the sea around New Zealand.
Dr Helen Neil, marine geologist and one of the key members of the NIWA team involved in creating the chart, says data collected by various sources over almost 150 years was used to produce a full colour image of the sea floor.
The high resolution of the data allows people to clearly see undersea valleys, peaks, cliffs and plateaus. Helen says this sort of detail had not previously been available because data covering some of the ocean floor were sparse and older mapping technology was less precise.
“The chart showcases the dynamic geography surrounding our small island nation. It’s an incredible view,” Helen says.
She says the chart will be used by councils and government decision makers across the country, from where it is likely to become a reference chart for many other users. It will help guide decision making in fisheries, science, conservation, and central and regional planning.
“We expect it to be in the hands of everyone from recreational fishers to those exploring energy and mineral opportunities,” Helen says.
The use of multibeam echosounders has been the key to the extensive and detailed data used to create the image.
Echosounders mounted to the hull of the vessel send beams of soundwaves to the sea floor. They measure the time it takes for the sound to travel back to the echosounder.
The data are collected and transferred into a software programme which builds up three-dimensional grids of the sea floor. These grids can then be turned into images and graphics.
The multibeam echosounder can record data in strips as wide as 7km and 2500m in depth and still retrieve detailed results. The tool can reach depths of up to 8km.
A collaborative effort
NIWA’s deepwater research vessel, Tangaroa, was used to collect part of the data used to produce New Zealand’s Marine Realm. NIWA also integrated information from Land Information New Zealand (LINZ), General Bathymetric Chart of the Oceans (GEBCO), as well as international surveys from United States, France, Germany, Australia and Japan to cover the area of New Zealand’s oceans.
New Zealand’s Marine Realm depicts boundaries such as the New Zealand Territorial Sea, which is an area out to 12 nautical miles from the coast, and New Zealand’s Exclusive Economic Zone, an area out to 200 nautical miles from the coast, over which New Zealand has rights to exploration, conservation and management of marine resources.
Order the poster
Poster-sized copies of the New Zealad Marine Realm map are available for order on the link below:
Note: This feature originally appeared in Water & Atmosphere, September 2015