ORC Heavy Rainfall Update #8 - 9 Dec 2019
9 December 2019
ORC Heavy Rainfall Update #8
Attributable to ORC Duty Flood Officer Paul Hannah:
Rain has now eased in the Otago headwaters and Lakes Wakatipu and Wanaka have begun to recede. Rivers feeding into the lakes, such as the Dart and Matukituki River, remain high but are also receding.
The forecast for the area through until Thursday 12 December is mostly clear, so the lakes should continue to steadily recede.
ORC modelling suggests the lakes will take 19 days from when they peaked to return to normal December levels. This does not mean the lakes will be in flood for 19 days, but is an indicator that lake levels will be high for several weeks. We will maintain a close watch on rain forecasts and river flows during this period.
The lakes responded to the headwater rainfall largely as predicted. Lake Wanaka reached a peak level of 280.38m, while Lake Wakatipu peaked at 311.36m, both around 4pm on Sunday.
Downstream, the Clutha / Mata-Au flows are expected to peak later today or tomorrow, and are likely to remain elevated for some time.
There is no significant rainfall predicted in other parts of the region and no high flows are expected in coastal, South Otago, Taieri catchment, and coastal North Otago catchments.
Flows are currently high in the Lower Waitaki River. Environment Canterbury has more information and advice on their website.
Unless the situation changes, the next update from ORC will be issued towards the end of the week, to report on the weekend weather forecast and recession rate of Lakes Wakatipu and Wanaka.
ORC has set up a dedicated webpage for this event (www.orc.govt.nz/) with links to up-to-date lake levels and flows, elevation maps for affected areas, and further resources.
Local authorities and other agencies will be sharing information on their social media and website pages:
Environment Canterbury: https://ecan.govt.nz/home/
Otago Civil Defence and Emergency Management: https://www.
Ignite Wanaka Business Chamber: https://www.facebook.
Queenstown Chamber of Commerce: https://www.facebook.com/