Hydrographic Surveys Underway

30 March 2009 Landscan Issue 48

New hydrographic charts are being produced for coastal areas at opposite ends of the country – off Great Barrier Island (Aotea Island) and Paterson Inlet/Whaka a Te Wera, off Stewart Island/Rakiura.

Hydrographic surveys are under way at both locations, which haven’t been surveyed for more than 40 years. “The finished results will mean there is safer navigation through these waters,” says Data Analyst (Hydrographic) Stuart Caie.

“Both surveys are challenging as the waters are shallow and there are numerous uncharted submerged rocks to be avoided.”

Paterson Inlet is a large natural harbour with a number of bays providing shelter to vessels of all sizes in nearly all weather conditions. It’s an area of significant natural beauty, with more than 90 percent of its shoreline within Rakiura National Park.

The inlet was partly surveyed in 1985. But with commercial activity – including tourism and aquaculture – increasing over the last 20 years, bigger vessels, including large cruise liners, are visiting more frequently. Discovery Marine Ltd of Tauranga is carrying out the survey.

The Great Barrier Island survey is being carried out by Australian firm iXSurvey. Maritime New Zealand requested the survey, which will result in large-scale charts covering the island’s entire west coast. The survey area includes the Mokohinau Islands to the northwest.

The Great Barrier coastal waters were last surveyed in 1965 and 1979, Stuart says. A full area search has never been achieved, and uncharted features may still exist. Commercial craft such as ferries, general cargo and product tankers regularly navigate through these waters and in summer, there are literally thousands of recreational craft in these waters at any one time.