Sunday, June 23, 2024

More rain radar data commissioned by Otago council

A new data processing service has been commissioned by the Otago Regional Council to extract further information from the MetService’s rain radar station in North Otago in a bid to boost potential flood responses in the region.

Council General Manager Operations, Dr Gavin Palmer says the rain radar information is now used operationally by the Council to improve and inform on potential flood responses, with enough data now available to be able to extract estimates on observed rainfall amounts.

“The rain radar data complements a range of data and information used by the ORC to inform and guide decision making during responses to potential or actual heavy rainfall events,” Dr Palmer says.

The radar data can estimate the location and severity of rain, where and how much rain is currently falling and has recently fallen. It can also estimate where rain is likely to go next and how quickly.

The rain radar update was prepared for noting at today’s ORC Safety and Resilience Committee meeting in Dunedin.

Other weather observations used by ORC include from on-the-ground rain gauges, lake water level stations, river flow and level stations and other organisations’ monitoring networks, Dr Palmer says.

However, the Hindon rain radar station, which has been operating since December 2021, now needs further data extracted on the quantitative estimates of rainfall variability, which requires “specialised data processing abilities”, he says.

Council has commissioned Weather Radar New Zealand/Mott McDonald to undertake the work. The first-year costs are around $120,000, then estimated annual costs thereafter are expected to be around $69,000; which has been budgeted for in both Long Terms Plans of 2021-2031 and 2024-2034.

While some rain radar data is publicly available on MetService’s website, the real-time “nowcast” information is not available.

However, Dr Palmer says public access will be revisited after ORC tests the data over a longer period, with possible access by 2027-28.

Dr Palmer says the current radar provides coverage of Dunedin, the lower Taieri, lower Clutha Mata-Au River catchments, and coastal Otago from the Catlins up to Waitaki.

Map of Aotearoa New Zealand showing MetService National Radar Coverage
MetService National Radar Coverage.

However, a gap exists in coverage largely because of the topography around Queenstown-Lakes and Central Otago, for areas which are experiencing rapid urbanisation.

Dr Palmer says filling this gap would assist with managing pluvial flooding risk in Queenstown, Wanaka, Luggate, Cromwell, Clyde, Alexandra, and Roxburgh.

One of the report’s recommendations to the committee today is that the Chair of the Otago Civil Defence and Emergency Management Group write to Government requesting weather radar coverage for Queenstown Lakes and Central Otago be considered.

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