Risk of landslips in Whanganui; flooding, slips on Whanganui-Manawatū region state highways

Anzac Parade State Highway 4 has reopened with a temporary speed restriction after a slip that blocked the highway between Georgetti Rd and Mt View Rd. Photo / Finn Williams

The Whanganui region is at risk of landslips as the ground dries out after the weekend’s torrential rain.

Whanganui District Council emergency manager Tim Crowe said people should remain wary in slip-prone areas.

When the ground was saturated with water, as it was from the weekend’s rain, any land with more than a 30 degree incline was at a higher risk of slips, Crowe said.

”Every time we get severe rain, when the ground gets soggy if you’re over 30 degrees … you get that increased risk,” he said.

In rural areas, land often had an incline of more than 60 degrees and places prone to slips included State Highway 4 Parapara and the Whanganui River Road.

Crowe said residents in those areas knew about the risks so adjusted their driving to account for the change in conditions and to be prepared.

”The up-river community who we work with all the time are aware of that; they watch it as well so get word from them occasionally.”

Within the city, places like Bastia Hill, Durie Hill and parts of Roberts Ave were more susceptible to slips, so he advised people to be aware when in those areas, especially at night.

”If you’re driving at night time, particularly in those environments up the River Road, the locals are really good with it, just take care,” he said.

People can find out the slope stability and steepness of land in an area via the district plan, available from the Whanganui District Council.

Crowe said the light wind and sunny weather in the region would help to dry out the land and the risk of slips would continue to diminish as the weather was expected to stay fine for the week.

State highways across the Whanganui-Manawatū region continue to be affected by the weekend’s wild weather.

At 6.30am on Monday, Waka Kotahi NZ Transport Agency reported a number of highway blockages around the region.

On SH1 at Mangaweka, the northbound lane is blocked near the intersection with Manui Rd due to a slip.

A slip has blocked the southbound lane of SH4 Parapara at Kākātahi near the intersection of Aotea Rd.

“Please drive with care in these areas and adhere to the temporary speed restrictions,” Waka Kotahi said.

SH3 Bulls to Lake Alice reopened at 9.30pm on Sunday.

SH54 remains closed due to flooding at Waituna between Kimbolton Rd and SH1.

Several highways that were closed on Sunday are now open but caution is needed. They are SH1 Marton to Mangaweka, SH3 Lake Alice to Whangaehu, SH4 Parapara between Parikino and Kākātahi and SH4 Anzac Pde near Bastia Hill, where there is a temporary speed restriction.