Heavy rain warning for South Canterbury could force re-evacuations near Ōpihi River – صحيفة الصوت

An “orange” level heavy rain warning means more nervous times for residents nearing the flood-damaged Ōpihi River stopbank near Pleasant Point.

Environment Canterbury said on Monday that residents in the Mill Rd area alongside the river could be evacuated again with the MetService rain warning covering the Canterbury Plains and the Canterbury High Country south of the Rakaia River.

Floodwaters severely damaged the stopbank on Wednesday and the Timaru District Council declared a State of Emergency after two of 10 people from the Mill Rd Huts area, who had voluntarily evacuated several hours earlier, went back to a property.

Residents were allowed back to their homes on Friday under strict conditions with an early warning system implemented but ECan now has lower flood alert levels in place for area with the MetService warning heavy rain from 1am Tuesday to 3am Wednesday.

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ECan rivers manager Leigh Griffiths, on Monday, said contractors and staff had worked over the weekend to ensure critical actions were carried out on the Ōpihi, Orari and Waitaki Rivers.

“In the Ōpihi, some of the flow has now been diverted away from the stopbank which has taken the pressure off. Rock has also been placed in front of the stopbank to slow down erosion.

“Erosion rates have slowed enough, and the risk reduced enough, that the Mill Road Hut residents have been allowed back under a set of strict conditions.”

Griffiths said there is a possibility Mill Rd residents could be evacuated again if the river levels rise.

“Foothill rain is expected tomorrow. Lower flood alert alarm levels have been set for rising water levels given the vulnerability of the stopbank.

“If certain levels are reached the Mill Road residents are required to leave.”

Griffiths said further damage to the stopbank is possible and will depend on river flows and braid alignments.

Griffiths added that in the Orari River there was some stopbank erosion and on the Waitaki River there was some land erosion.

Paul Cooper, the Timaru District Council’s group manager environmental services, said they were continuing to take advice from Environment Canterbury who are continuing to monitor the situation closely, including the potential evacuation of Mill Rd residents if things escalate.

MetService meteorologist David Miller said there was a possibility of the river levels rising as an add on to the heavy rainfall and severe weather in South Canterbury last week.

“Expect 100 to 130mm of rain to accumulate about the foothills, and lesser amounts elsewhere,” MetService said.

“Peak rates of 10 to 15mm per hour.

“Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.”

Miller said heavy rain is forecast to start on Monday evening and continue through to Wednesday due to a subtropical low pressure system coming in from the north.

The MetService website is forecast rain to being falling in Timaru around 7pm on Monday and the rate to about 1mm an hour through the night to 4am Tuesday when rainfall could reach 3mm an hour, rising to 4.6mm late morning with similar hourly levels forecast for the rest of the day.

“Thursday onwards it won’t be as bad with a south-westerly flow,” Miller said.

“There will be scattered rainfall in the second half of the week and over the weekend, but it will be a general improvement.”

A road snowfall warning has also been issued for Lindis Pass Rd (State Highway 8) from 8pm on Monday to 11am on Tuesday.

The MetService forecast says expect rain or showers and 10-15cm of snow to accumulate above 800 metres with lesser amounts lower down to 700 metres.