Hazards

The main hazards in our area include:

Flooding

The Kaimai and Coromandel ranges attract” high intensity rainfall events on a regular basis, making the area prone to flooding. River flooding is the most frequent and widespread natural hazard in the area (and the whole Waikato region).

The Kaimai/Coromandel Ranges generally have short, steep catchments, and rivers and streams that have a high sediment load – this makes them highly active and unpredictable, with short warning times before they flood.

The Waihou and Piako Rivers have a lower gradient and are more predictable, but are still prone to flooding.

The Kauaeranga River floods frequently, posing a threat to Thames and the adjacent areas in significant events. It is vulnerable to “flash” flooding. Waikato Regional Council has a sensor on the river and monitors flows at all time.

Much of the Hauraki Plains is very low-lying and subject to high groundwater tables (ponding) and flooding that result from flows that exceed protection scheme design standards

Learn more about what to do in a flood

Tsunami

Tsunami’s are a major hazard for the Thames Coromandel District (particularly the north and east of the peninsula) and the Hauraki District (particularly Whiritoa and Kaiaua).

Tsunami’s are also likely to cause significant river flooding in all three districts.

The primary sources of tsunami hazards include:

  • Distal (far-field): South America, particularly southern Peru, and Cascadia (North America) and the Aleutian Islands.
  • Regional: Solomon Islands, and the southern New Hebrides (Vanuatu).
  • Local: the Tonga-Kermadec trench to the north-east and the Hikirangi Trench off East Cape, Mayor Island and the undersea landslides to the north of East Cape.

Learn more about what to do in a tsunami

Severe Storms

Severe storm events occur across the Waikato region, but tend to severely impact the Thames Valley.

The western side of the Kaimai and Coromandel ranges are renowned for cyclonic winds. Extreme wind events have caused considerable damage and many injuries.  Historic events include those of 1936 and in 1978 when stronger than usual winds struck the region.  In 1978, winds of 140 knots were registered on top of Mount Te Aroha.  

The Hauraki Plains are vulnerable to frequent high wind events due to winds coming off the ranges, particularly during easterly storm events.  

Learn more about what to do in a severe storm

Earthquake

Earthquakes are often felt in the Thames Valley, with the greatest known threat coming from the Kerepehi fault.

 A large magnitude movement on this fault is considered capable of producing a significant earthquake hazard that will affect the towns of Thames, Matamata, Morrinsville, Te Aroha, and Paeroa ( s they are all within 10 kilometres of the fault).  

An earthquake on the Kerepehi Fault is also likely to generate reasonably large tsunamis

Learn more about what to do in an earthquake

Landslides

The Thames Valley is susceptible to landslide hazards, due its climate and topography.

Landslides are typically small-scale events (e.g. closing roads for brief periods). However, a landslide on the western side of the Coromandel and Kaimai Ranges has been identified as a potential significant hazard to the Thames Valley due to the impact debris flow could have on our towns.

Learn more about what to do in a landslide

Drought

The Thames Valley is one of the areas most typically affected by water shortage in the Waikato. The drought of 2008/09 resulted in direct, off-farm and total output economic impacts of over $2 billion within the Waikato.

Volcanic eruption

The most widespread, frequent and likely volcanic hazard to the Thames Valley is ashfall.

The most significant volcanic threat to area is Mayor Island, a caldera  volcano situated approximately 25km offshore on the east coast of the Coromandel Peninsula. The volcano has produced many explosive and effusive eruptions during its history, the latest of which occurred about 6,300 years ago.

Other volcanic threats from within the Waikato include Tongariro Volcanic Centre (recently active), Taupo Volcanic Centre (no eruptions in historic times), Maroa Volcanic Centre (active, but not considered a major hazard). Outside the Waikato, Mount Taranaki, Okataina Volcanic Centre and Auckland Volcanic Centre also pose volcanic threats.

Learn more about what to do in a volcanic eruption

Other Natural Hazards

Coastal Flooding and Erosion is a hazard along the western coast of the Coromandel Peninsula and in parts of the east coast, including Whitianga. Active coastal erosion areas occur primarily on the east coast of the Coromandel Peninsula, but also around harbours and river mouth along the west coast, including Mokau, Kawhia, Aotea and Raglan.

Rural fire impacts rural forest, scrub, peat and tussock areas to various degrees across the region.

Other resources

Want to know more about these hazards and how they are managed? Check out these resources:

Waikato Civil Defence Emergency Management Group Plan (pdf, 2mb)

Hazard and Risk Analysis (pdf, 590kb) (a supporting document to the Waikato Civil Defence Emergency Management Group Plan)

An overview of natural hazards in the Hauraki District (pdf, 2.5mb)

Buying flood prone property brochure (pdf, 923kb)

Owning flood prone property brochure (pdf, 526kb)

The Kauaeranga River flood protection scheme brochure (pdf, 1mb)