Lake Matahina

Lake Matahina
Tributaries: Rangitaiki River Drain: Rangitaiki River Major cities nearby: Whakatāne
New Zealand
Coordinates	38 ° 7 ′ 0 ″  S , 176 ° 50 ′ 0 ″  E Coordinates: 38 ° 7 ′ 0 ″  S , 176 ° 50 ′ 0 ″  E.
Data on the structure
Lock type:	dam
Height of the barrier structure :	79 m
Crown length:	396 m
Power plant output:	72 MW

The Lake Matahina is a reservoir in the region Bay of Plenty on the North Island of New Zealand .

geography

The lake is located in the valley of the Rangitaiki River , about 22 km southwest of the district capital Whakatāne . Flanked to the east by the Raungaehe Range , the reservoir extends along the former river bed of the Rangitaiki River over 6 km south. The lake was dammed directly in front of the small Māori settlement Te Mahoe , which is now at the foot of the dam.

Origin and use

The reservoir is used to generate electricity and regulate water. The Lake Matahina dam was built in the 1960s. The dam, which consists of greywacke at the core and various layers of ignimbrite on both sides , is a little over 79 m high and 396 m wide at the top and 366 m at the base. The optimal filling height of the reservoir is 76.2 m. The two turbines , each with an output of 36 MW, generate a voltage of 11,000 volts , which is then stepped up to 110,000 volts. After the lake had reached its target water level, electricity generation was started in January 1967.

Since the shore areas of the lake largely consist of steeply sloping rocks, the lake is not suitable for swimming or other water sports . Fishing is possible and allowed.

Lake Matahina - dam with power plant

Edgecumbe earthquake

The 1987 Edgecumbe earthquake had a significant impact on the dam. Since this was only 23 km from the epicenter , parts of the dam were damaged in the earthquake measuring 6.5 on the Richter scale . The dam lost water and 3,000 people had to be temporarily evacuated before the reservoir was emptied. The dam was repaired in 1988 and reinforced in the late 1990s in order to be able to withstand future, possibly even stronger, earthquakes. In the NZSOLD / ANCOLD Conference on dams in 2001, the dam was nevertheless given the “high” risk level. This means that the energy supply company Trustpower , which owns and operates the dam and power plant, is required to undertake a special risk management system.

swell

• Information board at the foot of the dam
• Management of the Trustport Ltd Dam Portfolio , Trustpower and Riley Consultants Ltd., NZSOLD / ANCOLD Conference on dams, 2001.

Individual evidence

1. ↑ New Zealand Disaster - Earthquake: Edgecumbe - Christchurch Library - (accessed January 28, 2010)
2. ^ Matahina Hydro Dam Seismic Hazard Assessment - New Zealand . Earthquake Engineering New Zealand , archived from the original on May 13, 2010 ; accessed on April 25, 2019 (English, original website no longer available).  
3. ^ The 1987 Edgecumbe earthquake - Te Ara - Encyclopedia of New Zealand - (accessed January 28, 2010)