NIWA

Coasts

Latest news

Watch out for jellyfish blooms

28 December 2020

Jellyfish blooms are likely to be a common sight this summer with rising ocean temperatures one of the main causes of substantial population growths.

Chance find leads to first look at coral larvae

Media Release

12 November 2020

Small orange flecks spotted floating around in a respiration chamber at a NIWA laboratory have led to a discovery about the spawning habits of a deep-sea stony coral in New Zealand waters.

Underwater robot getting close-up look at Kaikōura Canyon

Media Release

8 October 2020

A six-metre long orange underwater robot is flying through the Kaikōura Canyon for the next month collecting information on how the canyon has changed since the 2016 earthquake.

Scientists conducting snapper research off North Island’s west coast

Media Release

6 October 2020

People along the Kapiti and Wanganui coast may spot NIWA’s research vessel Kaharoa operating close to shore in the next few weeks as scientists carry out a survey of snapper, tarakihi, red gurnard and John Dory.

Our work

Changes in juvenile fish habitats

NIWA is looking for people who have had a long association with the Hauraki Gulf or Marlborough Sounds to help them with a research project on juvenile fish habitats.

Coastal adaptation to climate change

NIWA is developing guidelines and advice to help coastal communities adapt to climate change.

Plastic pollution processes in rivers

Most of the plastic in the ocean originates on land, being carried to the estuaries and coasts by rivers. Managing this plastic on land before it reaches the river could be the key to stemming the tide of marine-bound plastics. The aim of this project is to understand the sources and fate of plastic pollution carried by urban rivers using the Kaiwharawhara Stream as a case study.

Restoration of seagrass beds in Whangarei Harbour

Seagrass beds form an important undersea habitat for small fish, seahorses and shellfish in New Zealand.

Latest videos

Shifting Sands

Dr Joshu Mountjoy discusses NIWA's work in assessing the tsunami hazard just south of Kaikoura.

Find out more about this research.

Antarctic Coastal Marine Life in a Changing Climate

NIWA marine ecologist Dr Vonda Cummings discusses the likely effects of climate change on marine invertebrates living on the seafloor of the Ross Sea coast.

Next Stop Antarctica

Our Far South is an expedition that aims to raise New Zealanders' awareness of the area south of Stewart Island. Gareth Morgan, Te Radar, scientists and 50 everyday Kiwis are onboard to learn and then share their experience. This is the first video produced by them, showing some of the highlights of the trip so far.

No.12 2006

Better tools mean improved knowledge and services

Smart buoy for coastal monitoring

A flexible way to model sediment dispersal

Getting intimate with aquatic sediments

GeoEel sees beneath the seafloor

Winds & Storms

Winds & Storms - Looking back at the Wahine Storm

Waves

Wave climate around New Zealand

Wave climate around New Zealand
NIWA has recently implemented a large wave model (NIWAM) for the oceans around New Zealand. This is based on WAM, a 3rd generation model which accommodates the processes of wind generation, white-capping and bottom friction, and includes a direct estimate of non-linear energy transfer through four-wave interactions. NIWAM has been established on a 1.125° resolution grid (see image below) covering the Southwest Pacific, New Zealand, Australia and the Southern Ocean.

Tsunami

Tsunami is a Japanese word meaning great wave in harbour

Verifying the wave model

Verifying the wave model
The results from the model hindcast have been compared with data from wave buoys deployed at various times in the past at several sites around New Zealand (shown below).

Foveaux Strait Buoy
This was located in 100 m water depth. Model results were corrected for the effects of limited fetch to the coast before comparison with the data (shown below, click to enlarge).

Mangawhai Buoy
This was located in 30 m water depth, in a site sheltered by surrounding land, and affected by refraction of waves over the seabed topography the variable depth.

Surf zone processes

NIWA coordinates a network of remote video cameras, called Cam-Era, which regularly monitors coastal and river behaviour in real-time.

Sumatra

Sumatra tsunami recorded at 1-minute sampling intervals at 9 sites:
a) Date/time in NZ Standard Time (UTC+12), with earthquake (EQ) time shown.
b) Elapsed time in hours since the earthquake occurred.

Sumatra tsunami recorded at 5-minute sampling intervals at 19 sites:
a) Date/time in NZ Standard Time (UTC+12), with earthquake (EQ) time shown.
b) Elapsed time in hours since the earthquake occurred.

Tsunami run-up height reached up to 12 m in Khao Lak (Thailand) as shown by damage to tiles on roof.

Solar Semidiurnal Tide (S2) - animation

Solar semidiurnal tide (S2) as an animation.

Waves from Satellites

Waves from Satellites
Waves are available from a number of satellite sensors, including radar altimeters and synthetic aperture radar (SAR).

A radar altimeter aims a narrow beam directly downwards. From the spread in the return signal, the wave height can be measured.

Solar Semidiurnal Tide (S2) - chart

Solar Semidiurnal Tide (S2)

North Island tidal currents

Twice-daily M2 tidal currents animation around the North Island of New Zealand based on a TIDE2D model.

Maritime Hazards & Support

Tidal and surface currents - besides tidal height, the NIWA tide model of New Zealand's EEZ also produces tidal currents. For the first time, a detailed overall picture has emerged of the strength (speed) and direction of tidal flows on the continental shelf and around various islands, headlands and straits.

Lunar Semidiurnal Tide (M2)

Animation of the lunar semidiurnal tide (M2) in New Zealand.

Diurnal Tide (K1)

Hazard planning, awareness and building resilient communities

Sea level on the move?
Effect of global warming
Educational CD-ROM “New Zealand’s Sandy Coasts”
Coastal & Storm Hazards Workshop

Sea level on the move?

Long-term sea level varies at timescales of years, decades and centuries. Before the long-term trend in sea-level rise can be obtained from any sea-level record, we must understand the fluctuations that occur over years and decades. The longest sea-level record in New Zealand is from the Port of Auckland (click to see accompanying figure).

Foveaux Strait M2 Tidal Component

This animation shows the chief tidal current in Foveaux Strait. Tidal currents on the west coast of Stewart Island are small, but around the northern and southern coasts of the island and in Bluff Harbour and Oreti Estuary there are strong tidal currents. Overall currents (not shown here) in Foveaux Strait however, are strongly wind-driven with the prevailing wind being from the west. The Southland current, which carries water from the subtropical convergence west of New Zealand, flows through Foveaux Strait.

Coastal erosion & sediment systems

NZ has a range of different types of coasts, and so very different coastal erosion and sediment systems.

Tides

Tide forecasts, Sea-level network, Tidal model of New Zealand’s EEZ and Red-alert days for coastal flooding

Cook Strait M2 Tidal Component

Currents in the Cook Strait are made up of many different components, chiefly the tidal and storm driven currents.

Banks Peninsula M2 Tidal Component

The tidal current shown here is the main component of currents around Banks Peninsula.

Research team

The study team is interdisciplinary and includes sedimentologists, physicists, oceanographers, and modellers working on a range of research projects within the programme.

Publications

Publications from the physical hazards team.

New Zealand's icy visitors - past and present

Scour marks of the seabed were probably made by an iceberg measuring between 2 and 5 km long.

November saw some unusual visitors to New Zealand waters, with several icebergs reaching the South Island’s east coast. NIWA oceanographer Dr Mike Williams estimated that the bergs probably came from the Ronne Ice Shelf on the other side of Antarctica.

Estuary health check

Estuary health check
Scientists from NIWA and Canterbury University are developing a diagnostic toolkit to assess the health of the Avon-Heathcote Estuary before and after a new wastewater outfall is installed.
Treated wastewater has been discharged into the estuary for about 40 years. The high levels of nutrients it contains may be responsible for problem blooms of sea lettuce in summer.

Customary Coastal Management Workshop

Karengo harvest at Mahia. (Photo: Sheryl Miller, NIWA)

21–22 June, Te Papa, Wellington.
NIWA’s National Centres for Coasts & Oceans and Fisheries & Aquaculture will host a workshop to highlight how increased scientific knowledge can advance customary management of the coastal environment.
Increasingly, iwi and managers of taiapure and mātaitai (traditional fishing grounds) have regulatory responsibilities for customary management of the coastal environment and kaimoana resources.