page_title: Clutha River
section_title: Floods
hierarchical_section_title: Clutha River / History / Floods
caption_attribution_description: English: Balclutha Road Bridge crossing the Clutha River, Balclutha, New Zealand, photographed by James Dignan (en:User:Grutness) in February 2008
context_page_description: The Clutha River / Mata-Au is the second longest river in New Zealand and the longest in the South Island. It flows south-southeast 338 kilometres through Central and South Otago from Lake Wanaka in the Southern Alps to the Pacific Ocean, 75 kilometres south west of Dunedin. It is the highest volume river in New Zealand, and the swiftest, with a catchment of 21,960 square kilometres, discharging a mean flow of 614 cubic metres per second. The Clutha River is known for its scenery, gold-rush history, and swift turquoise waters. A river conservation group, the Clutha Mata-Au River Parkway Group, is working to establish a regional river parkway, with a trail, along the entire river corridor. The name of the river was changed to a dual name by the Ngai Tahu Claims Settlement Act 1998.
context_section_description: Several major floods have occurred on the Clutha, most notably the “Hundred year floods” of 14–16 October 1878 and 13–15 October 1978. The 1878 flood is regarded as New Zealand's greatest known flood. During this, a bridge at Clydevale was washed downstream, where it collided with the Balclutha Road Bridge, destroying the latter. The course of the river near its mouth was greatly affected, with the mouth moving north from its former outlet to create two new outlets at its current mouth. The thriving town of Port Molyneux, which was located at the river's (former) mouth, dwindled as a result and today no longer exists.
  The 1978 flood breached the banks of rivers from the Oreti in the south to the Tokomairaro. Over 12,000 hectares (30,000 acres) of land was inundated, with the loss of over 21,000 livestock. Towns and areas affected stretched from Makarora in the north to Invercargill in the south. The town of Wyndham was completely evacuated, and the towns of Balclutha, Milton and Mataura were seriously affected with many residents moved. The small settlement of Kelso on the banks of the Pomahaka River was completely abandoned and was not rebuilt once the waters subsided.  At its peak, at 6.00 a.m. on the 15th, the Clutha's flow was measured at just over 4,500 cubic metres per second (160,000 cu ft/s).
  A major flood in 1999 seriously damaged river communities, especially Alexandra. The flooding in Alexandra was attributed to a rise in the riverbed, resulting from silt loading in the Roxburgh reservoir behind the Roxburgh Dam downriver from the town. The 1999 flood had significantly higher water levels in Alexandra than the 1878 flood, despite being only 80% of the volume of the latter.
caption: The Clutha passes under the third Balclutha Road Bridge. The first bridge at this site was destroyed during the flood of 1878.
exif: {}