<- Homepage: What lies beneath?
What is hydrographic surveying?
The field trip kicks off overlooking Tūranganui-a-Kiwa Poverty Bay. Brad from Toitū Te Whenua Land Information New Zealand (LINZ) takes us through the what, why and how of hydrographic surveying.
- Explain what hydrographic surveying is in your own words.
- Why do nautical charts need to be updated?
- Apart from updating nautical charts, what other reasons are there for seabed mapping?
Aboard Tupaia | The multibeam sounder
All aboard! Head out into Tūranganui-a-Kiwa Poverty Bay with the Discovery Marine Limited hydrography team. Senior Hydrographic Surveyor, Kate, is at the surveyor's desk and talks us through how the multibeam echo sounder works.
- How many beams does the sounder on Tupaia send out?
- What does the sounder measure?
Positioning – how do we know where we are?
Rian from Discovery Marine Limited explains the technology behind knowing their position anywhere and anytime while out on the water.
- What is the primary technology used by the crew to know where they are?
- What does the motion sensor do?
A skipper’s role in seabed mapping
Tupaia's skipper, Jordie, gives an overview of the skipper's role during seabed surveys and why this is such an important link with the rest of the crew.
- What are some of the things a skipper needs to look out for to ensure safe boat operation?
- Why might a skipper choose to not rely totally on a nautical chart for an area?
Seabed survey gadgets
Hayes from Discovery Marine Limited shows us three cool pieces of kit that the hydrography team use when conducting seabed surveys.
- What can change the speed of sound waves travelling through the water column?
- How does the grab sampler help hydrographers with their seabed surveys?
- What might an ROV take video footage of?
Processing the collected data
Get an idea of how the data collected during a seabed survey is processed.
- What is meant by "cleaning the data"?
- What are the benefits of updating nautical charts?
Using the data back at Toitū Te Whenua Land Information New Zealand (LINZ)
A lot of work goes into collecting data during a seabed survey. How is this data used to create a nautical chart for mariners to use?
- What two things is the survey data downsampled to when making a basic nautical chart?
- What are the main differences between a small scale and large-scale chart?
Helping improve management of marine resources
At Te Tapuwae o Rongokako marine reserve, Brad from Toitū te Whenua Land Information New Zealand (LINZ) explains the environmental application of seabed mapping.
- What is used to determine fish life living in an area?
- What sorts of areas would be worth putting into marine reserve?
