Spectacular drone footage of the flood damage caused to State Highway 72 at Arundel.

Drone footage over route 72 at Arundel has shown the full extent of damage caused by a flooding Rangitata River, cutting the South Island in half.

Rangitata, about 45 kilometres north of Timaru, was put into a state of emergency on Saturday as the Rangitata River burst its banks following significant rainfall that led to widespread flooding and slips, considered a one in 20 year event.

The Rangitata Bridge at State Highway 1, and the bridge at Arundel on route 72, will remain closed for at least the next 36 hours, Timaru Civil Defence spokesman Stephen Doran told Stuff on Sunday.

JOHN BISSET/STUFF A photo from the air on Sunday morning showing the flooded Rangitata River on the south side.

Are you affected by the evacuations? Email newstips@stuff.co.nz

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There are no other routes in and out of the area, and with mobile and internet connections in South Canterbury, out for at least 12 hours from Saturday afternoon, the island was cut off.

JOHN BISSET/STUFF Rangitata, about 45km north of Timaru, was put into a state of emergency in December 2019 as the Rangitata River burst its banks following significant rainfall that led to widespread flooding and slips, considered a one in 20 year event.

While landline, broadband and mobile services are up and running again in some parts of the region, the roads' closures means many travellers are stranded on either side of the river.

The Orari River Bridge, on State Highway 79, has also been closed.

Doran said viewing the drone footage, which the council posted to social media on Sunday morning, council staff had not been surprised by the damage.

JOHN BISSET/STUFF A photo from the air taken on Sunday morning over Arundel showing the irrigation ponds and damage to the southern end of the road.

"It was what we were expecting.

"The water is running that high and that fast - it's pretty bad."

When staff were finally able to get access to the road on State Highway 72, they would be creating temporary surfacing, he said. Just when this would happen was unknown, but he said he would not be until Monday, at least.

1 of 19 JOHN BISSET/STUFF Floodwaters in the normally dry southern arm of Rangitata River. 2 of 19 JOHN BISSET/STUFF The flooded Rangitata River mouth to the north of the Rangitata Huts settlement on December 8, 2019. 3 of 19 JOHN BISSET/STUFF An aerial photo showing how widespread the flooding from the Rangitata River is. 4 of 19 JOHN BISSET/STUFF An aerial view looking north showing how the floodwaters from the Rangitata River have affected State Highway 1 and the main trunk rail line. 5 of 19 JOHN BISSET/STUFF A vehicle makes its way through flooding on Old Main South road near Rangitata. 6 of 19 JOHN BISSET/STUFF Floodwaters from the Rangitata River cover Old Main South Rd. 7 of 19 JOHN BISSET/STUFF Rangitata River flooding at the Rangitata village intersection of State Highway 79 and State Highway 1. 8 of 19 JOHN BISSET/STUFF A westward look at the flooded Rangitata River, towards the Rangitata irrigation ponds. 9 of 19 JOHN BISSET/STUFF Flooding at Arundel showing irrigation ponds and southern end road damage on highway 72, the Inland Scenic Route. 10 of 19 JOHN BISSET/STUFF The flooded Rangitata River. Photo taken at Arundel showing southern approach to the closed bridge on highway 72, the Inland Scenic Route, plus roading damage and the irrigation scheme. 11 of 19 JOHN BISSET/STUFF The closed highway 72 bridge across the flooded Rangitata River at Arundel on the Inland Scenic Route. 12 of 19 JOHN BISSET/STUFF The flooded Rangitata River at Arundel on highway 72, the Inland Scenic Route. 13 of 19 JOHN BISSET/STUFF Rangitata River bridges showing flooding on the south side. 14 of 19 JOHN BISSET/STUFF The flooded Rangitata River and the road and rail bridges taken from the south side on December 8, 2019. 15 of 19 JOHN BISSET/STUFF The flooded Rangitata River at Arundel with the irrigation scheme's ponds behind. 16 of 19 JOHN BISSET/STUFF Damage to the main trunk railway line from Rangitata River floodwaters on December 8, 2012. 17 of 19 JOHN BISSET/STUFF The flood damaged main trunk rail line at the Rangitata River on the December 8, 2019. 18 of 19 JOHN BISSET/STUFF Road and rail bridges across the flooded Rangitata River looking south. 19 of 19 JOHN BISSET/STUFF Flooding in the normally dry section southern arm Rangitata River.

"The road will definitely remain closed tonight."

He said for now the main focus was to restore the necessary north south link at Arundel.

"Timaru Civil Defence is prioritising the upper Rangitata bridge crossing as it will see water levels drop to a manageable level hours before the downstream bridge at State Highway 1."

BEJON HASWELL/ STUFF The Rangitata River from the air on Saturday after it burst its banks on Saturday morning.

Timaru emergency operations centre controller Justin Bagust said district roading contractors were now assembling heavy machinery at the southern approach to the road to be ready as soon as the water levels subside.

"We're aware of the importance of the north south link and by prioritising this route we can hopefully have a passable solution for people as soon as possible," he said.

"It still remains a dynamic situation, and we can't give any indication of a timeline at the moment, but we'll have updates as soon as we can.

1 of 14 BEJON HASWELL/ STUFF State Highway 1 and the main trunk rail line are flood by the Rangitata River after it burst its banks on December 7, 2019. 2 of 14 BEJON HASWELL/ STUFF 07122019. News. Photo: Bejon Haswell/Timaru Herald. The Rangitata River from the air after it burst its banks on saturday morning. 3 of 14 BEJON HASWELL/ STUFF The Rangitata River from the air after it burst its banks on December 7, 2019 with State Highway 1 to the bottom and the main trunk rail line above. 4 of 14 BEJON HASWELL/ STUFF The Rangitata River from the air after it burst its banks on December 7, 2019. 5 of 14 BEJON HASWELL/ STUFF The Rangitata River from the air after it burst its banks on December 7, 2019. 6 of 14 BEJON HASWELL/ STUFF The Rangitata River from the air after it burst its banks on December 7, 2019. 7 of 14 BEJON HASWELL/ STUFF The Rangitata River from the air after it burst its banks on December 7, 2019. 8 of 14 BEJON HASWELL/ STUFF The Rangitata River from the air after it burst its banks on December 7, 2019. 9 of 14 BEJON HASWELL/ STUFF 07122019. News. Photo: Bejon Haswell/Timaru Herald. The Rangitata River from the air after it burst its banks on saturday morning. 10 of 14 BEJON HASWELL/ STUFF The flooded mouth of the Rangitata River on December 7, 2018. 11 of 14 BEJON HASWELL/ STUFF Bob Mortimer and Russell Wood listen to the Civil Defence radio from the Rangitata Huts to keep up to date with the flooding information. 12 of 14 BEJON HASWELL/ STUFF Glenn Shaw, a Rangitata Camp resident a police warning tape roadblock. 13 of 14 supplied The high floodwaters at the Rangitata bridge on State Highway 1. 14 of 14 supplied The high flood waters going under the Rangitata River bridge on State Highway 1 on December 7, 2019.

"We'd ask people to stay where they are at the moment and not to drive up to the bridge, as it will still be some time before we have any progress and we need to ensure access for heavy vehicles and supplies."

Further updates would be posted on social media and the council's website, he said.

Waka Kotahi NZ Transport Agency system manager Pete Connors said "until the waters recede, we cannot get in to do the repairs needed".

Bejon Haswell/ Stuff Civil defence Communications Manager Stephen Doran speaks about the Rangitata River and road closing.

"We have crews and machinery ready to reinstate the highway and ensure it is safe for all road users once the flood waters from the river's tributaries have been contained back into their main flow."

A state of emergency was declared in the Timaru District on Saturday following significant rainfall that led to widespread flooding and slips, considered a one in 20 year event.

Residents between McLelland, Orion Rangitata Mouth roads, and Rangitata River, were also ordered to evacuate the area immediately on Saturday, those who had yet to leave were later told to stay put - and to call 111 if they felt unsafe.

BEJON HASWELL/ STUFF The Timaru Civil Defence centre is a hive of activity on Sunday morning following the Rangitata River flooding.

Speaking to Stuff outside the Timaru District Civil Defence headquarters on Sunday morning, spokesman Stephen Doran advised commuters in the South Canterbury region to stay put.

"We think it will be at least 36 hours, and possibly more, until we can assess the damage of the bridges," Doran said.

"The Rangitata River is dropping, but it's happening very, very slowly, and there is still a safety risk."

1 of 15 JOHN BISSET/STUFF A damaged power pylon sits in floodwaters from the Rangitata River. 2 of 15 JOHN BISSET/STUFF A crumpled power pylon in the middle of the flooded Rangitata River on December 8, 2019. 3 of 15 JOHN BISSET/STUFF A toppled power pylon on the south side of the flooded Rangitata River on December 8, 2019. 4 of 15 JOHN BISSET/STUFF A crumpled power pylon on the north side of the flooded Rangitata River on December 8, 2019. 5 of 15 JOHN BISSET/STUFF A toppled power pylon on the south side of the flooded Rangitata River on December 8, 2019. 6 of 15 JOHN BISSET/STUFF A mangled power pylon lies in the flood-ravaged Rangitata River near Arundel. 7 of 15 JOHN BISSET/STUFF A crumpled power pylon on the north side of the flood-hit Rangitata River on December 8, 2019. 8 of 15 JOHN BISSET/STUFF Damaged power lines dangle from pylons near Arundel in South Canterbury on December 9, 2019. 9 of 15 JOHN BISSET/STUFF Damaged power Pylons near Arundel in South Canterbury on December 19, 2019. 10 of 15 JOHN BISSET/STUFF Lines hang from a damaged power pylons near Arundel in South Canterbury on December 9, 2019. 11 of 15 JOHN BISSET/STUFF The sun rises over damaged power lines on the Arundel-Rangitata Rd near Arundel in South Canterbury on December 9, 2019. 12 of 15 JOHN BISSET/STUFF Damaged power lines on Arundel-Rangitata Rroad near Arundel in South Canterbury on December 9, 2019. 13 of 15 JOHN BISSET/STUFF Damaged power lines dangle from a pylon near Arundel in South Canterbury on December 9, 2019. 14 of 15 JOHN BISSET/STUFF A crumpled power pylon on the north side of the flooded Rangitata River on December 8, 2019. 15 of 15 JOHN BISSET/STUFF A damaged power pylon near Arundel in South Canterbury on December 9, 2019.

The river is flowing at around 920 cumecs at the gorge recorder, falling slowly from its peak of around 2280 cumecs.

Doran said the river breaks have caused significant damage to the approach to both roads.

"We will have to wait for the water levels to drop before the damage can be properly assessed. This is likely to take some time.

"We would advise against travelling to the bridge as you will not be able to cross."

Doran said civil defence operations were now active in Timaru, Geraldine and Temuka. If the situation worsened, they were looking to call in assistance throughout Canterbury.

Mobile and internet connections were also down for several hours throughout South Canterbury.

"We had teams of people putting up posters in affected areas," Doran said.

"We're hoping that the mobile and phone services will become less sporadic over the day. We're currently in a bit of a holding pattern."

Alpine Energy has also reported power outages at Arundel, Belfield, Orton and Rangitata due to "severe weather". Power is expected to be restored by 12.30pm.

According to a warning on Environment Canterbury's website, while river flows are now dropping, overflows into those areas already flooding will continue today.

"New problems can still develop on the river as the flow recedes and flow channels within the riverbed shift around," the website says.