Flooding infrastructure operating as result of Cyclone Gabrielle

Key pieces of flood infrastructure are set to operate as rainfall from Cyclone Gabrielle moves through waterways across the Horizons Region.

Horizons Regional Council incident controller Craig Grant says much of the forecast rain has fallen across the region, although there will still be occasional heavy showers.
“A lot of our catchments have peaked and water is moving through them. The Ākitio, Wainui and Owahanga rivers in Tararua are all dropping, while the Pohangina and Ōroua rivers have peaked. The Rangitīkei River at Mangaweka is also dropping.
“The Kopane spillway started operating on Tuesday afternoon. This occurs when the Ōroua River gets to a certain level, with water diverted through drainage networks and into farmland on the Taonui Basin. The spillway is designed to work this way and landowners are contacted beforehand.”
“Makino floodgates are not required to operate at this stage, but an operation of the Moutoa floodgates (between Foxton and Shannon) is likely to take place about 7pm Tuesday.

“Opening Moutoa floodgates earlier would have little benefit on the upper reaches of the system, as the water still flows down the catchment in that direction. We also need a certain level of water before we can open the floodgates to ensure the water flushes through. We expect the Manawatū River to stay within its channel until the gates are opened, at which point water will also flow through the Moutoa spillway.
“Water may still be seen overtopping stopbanks in certain parts of the region, which is different from a stopbank breach. It is not unusual for water to be seen outside of the main river channel during significant weather events.”

Mr Grant says a helicopter was used on Tuesday afternoon to survey impacted parts of the region, such as Tararua and Pohangina.
“The flight gave us valuable information about the extent of the flooding. This is a significant event, and people in some parts of the region will feel it is similar to the 2004 flood event.”

“We continue to work with Palmerston North City Council to ensure people are kept informed about the small risk at Te Matai Road, where work was being done to prevent erosion. We plan to closely monitor the site throughout the night.
There are extensive road closures throughout the region, including washed-out bridges, so people should avoid travel as much as possible, says Mr Grant.

“People should check with their city or district council for local road closures and Waka Kotahi for state highway information. We are aware of misinformation regarding state highway closures, but Waka Kotahi has told us they expect roads between Palmerston North and Whanganui to remain open.”
Up-to-date information on river heights and rainfall is available via Horizons 24-hour toll-free Waterline 0508 4 FLOOD or via our website www.horizons.govt.nz.
Updates will also be posted to the Manawatū-Whanganui Civil Defence page: https://www.facebook.com/civildefencemanawatuwhanganui/
For weather forecasting information please see www.metservice.co.nz. For road closures, delays, and warnings please see https://www.journeys.nzta.govt.nz/manawatu-whanganui/
For sandbag and evacuation information please contact your local city or district council and stay tuned to your local radio stations for another option for civil defence updates.