9 March 2017
Land Information New Zealand (LINZ) has made another list of the quirky facts about New Zealand that it comes across as it makes maps, charts our seas, manages red zone properties and much more.
1. Sea level isn’t the same around the country
We talk about height above sea level when we measure mountains, but what’s sea level? The answer depends on where, because it varies. So for example, the sea on the west coast is higher than on the east.
To help answer questions like these and to help surveyors, engineers and others, LINZ has developed a more consistent reference for measuring heights. Called a vertical datum, it uses gravity rather than sea level as a benchmark.
2. But gravity isn’t the same everywhere either
This doesn’t mean you can go moon walking in Kaitaia – the difference is so slight you won’t feel it, but it can change from place to place due to the landscape, and factors like the density of rock in the earth’s crust.
To create their height reference system, LINZ flew the length and breadth with a specialist plane for gathering gravity measurements. They then analysed the results to produce a system that’s accurate to within a couple of centimetres.
3. Our whole coastline is about 20,500km long
In creating its topographic maps, LINZ can make all sorts of measurements of our land and its features. When it comes to the coastline, the South Island on its own is 6000km, the North Island 8500km, and Stewart Island/Rakiura is 700km. Counting outer islands like the Chatham Islands, Auckland Island, Snares Islands/Tini Heke etc. brings the total up to 20,500km.
4. The long and the short of it
LINZ is home to the New Zealand Geographic Board Ngā Pou Taunaha o Aotearoa, which is responsible for the authoritative record of the country’s place names. These include one of the longest place names in the world, Taumatawhakatangihangakoauauotamateapokaiwhenuakitanatahu, for a hill east of Dannevirke, but also our only two letter, and so shortest place name, Og, which is a hill in the mid-Canterbury foothills on the way to Arthur’s Pass. Its neighbours are the hills Gog and Magog.
5. Golden Bay / Mohua is home to New Zealand’s highest tide.
LINZ creates the tide predictions that get used for shipping, fishing and planning weddings on the beach. Pūponga, in Golden Bay / Mohua, is where they see the greatest difference between high and low tide. There’s sometimes 4.8 metres between the two.
It’s a big change, but it’s nothing compared to Canada’s Bay of Fundy where the difference between low and high tide can exceed 16 metres.
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