Horizons Regional Council's Mangaweka webcam showing the rising Rangitīkei River. Photo / Supplied
Overnight rainfall from Cyclone Gabrielle has resulted in high flows in the Rangitīkei, Ōroua, Pohangina and Manawatū rivers.
Horizons Regional Council incident controller Craig Grant says duty officers monitored the situation through the night, with actual rainfall providing a clearer picture of what to expect today.
“The upper Rangitīkei has received a decent amount of rainfall and we are modelling about an 8m peak at Mangaweka at midday today. This is a decent level for the Rangitīkei, but beyond a bit of overspill in the upper reaches we expect it to remain in its channel.”
He says duty officers will monitor Tangimoana.
“The high river flows mean drains in the village won’t be able to clear as quickly. However, the majority of localised rainfall is due to fall before the peak passes through and a contractor is on standby to open the stopbank to help clear surface water if required.”
Craig says the Ōroua River is modelled to peak near 4m at Armadale (near Cheltenham) mid-to-late morning.
“Again, we expect this to remain in its channel, although there is a gap in stopbanks near Te Arakura Rd downstream of Feilding, so we will be on site to keep an eye on water levels. We have also installed a flood barrier on Hoihere Rd as a precautionary measure for that portion of the Ōroua River. Doing so has meant emergency management staff get some practice with this particular asset as well.”
The Pohangina River is modelled to reach about 3.5m at Mais Reach (downstream of Raumai Reserve) mid-morning.
“This has resulted in some road closures in the area. While we don’t anticipate any particular issues here, it will contribute to higher flows in the Manawatū.”
He says the upper Manawatū has also received a fair amount of rainfall and the river is still rising.
“At this point it’s harder to determine exactly how high the Manawatū will get, but we are planning an operation of the Moutoa floodgates (between Shannon and Foxton) this evening. Leaseholders of the Moutoa spillway will be contacted this morning and gate crews are on standby. The Makino floodgates are not required to operate at this stage.”
Another consideration in Manawatū is the stopbank work underway at Te Matai Rd, he says, with the work aimed to protect it from erosion.
“The work is not yet complete, so there is a small risk a few homes could experience some surface water flooding and require evacuation if the Manawatū River rises significantly. While we anticipate the river will remain in its channel, we have worked with Palmerston North City Council emergency management staff to give potentially impacted property owners a notice to prepare just in case. There is no other risk to properties alongside the awa and if you haven’t been contacted last night, your property is not involved.”
In regards to the Ruapehu, Whanganui and Horowhenua districts, Craig says there has been some rain but the catchments are coping. There are high river flows in the Tararua district, particularly on the Wainui River.
“The campground at Herbertville has been cleared and the flood siren may go if the river keeps rising. We’re also monitoring Ākitio River levels and what this means for road access to the coastal community when combined with localised rainfall and tidal surges.”
He says Horizons is keeping in close contact with its city and district councils and will remain so through the day.
“We’re aware that councils have closed a number of roads, campgrounds and reserves across the region in response to this event. This includes Tōtara Reserve, which was closed yesterday. There has also been power outages overnight due to the gale-force winds that the majority of the region has experienced. We urge people to take care when driving and to watch out for fallen trees or debris.”
There is still an orange wind warning in place for the region, an orange rain warning for the Tararua district, and possible storm surges for the east coast.
“The forecast suggests the majority of rainfall will occur this morning and we will provide another update this afternoon.”
Up-to-date information on river heights and rainfall is available via Horizons’ 24-hour toll-free Waterline 0508 4 FLOOD or via its 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 go to www.metservice.co.nz. For road closures, delays, and warnings go to https://www.journeys.nzta.govt.nz/manawatu-whanganui/
For sandbag queries, contact your local city or district council and stay tuned to your local radio stations for Civil Defence updates.