The Clarence River Reserve might look a bit different after the earthquakes last night. Aside from the potential for rockslides due to the steep rocky terrain in that area the Clarence river dammed then burst the dam sending a 2 metre high flood of water downstream.

Wall of water’ as quake dam bursts on Clarence River

A “large wall of water” is surging down the Clarence River and nearby residents are being warned to move to higher ground as soon as possible.

A slip dammed the river about 10 kilometres upstream from the mouth, north of Kaikoura, after Monday morning’s 7.5-magnitude earthquake. The banked-up water burst through the wall of debris about 4.20pm. A helicopter in the area saw the breach and the water beginning to roll downstream.

There are eight to 10 houses in Clarence, at the river mouth, and several more upstream.

Authorities are searching for a group of kayakers thought to have moved to higher ground after their gear was found by the river bank.

A separate group of 16 rafters on the flooded river this afternoon have been contacted by police. They were upstream from the slip site, away from the danger area.

Environment Canterbury (ECan) had warned people to stay away from the Clarence River and nearby floodplain areas.

Ongoing earthquakes meant there were risks of landslides into North Canterbury rivers.

Anglers were urged to stay away from the river due to the risk of flooding.

The river is one of New Zealand’s largest.

From: http://www.stuff.co.nz/national/86436608/warning-as-large-clarence-river-dammed-by-landslide

Some more info about damage in the region.

Quake carnage raises 10m new hill at Clarence River

A 10 metre high hill pushed up by the 7.5 earthquake on a previously flat river paddock has left valley farmers along the Clarence River completely flabbergasted.

The hill has appeared from nowhere on farmland along river flats about eight kilometres up the valley.

“It was completely flat and now there is a 30 foot hill in the middle of Priam’s Flat and the whole river has come up,” said Matariki farmer James Murray. “it’s unbelievable and if you hadn’t know what it looked like before you would never notice it.”

The farmland is owned by the family of Murray’s cousin John Murray of Woodbank, whose homestead was destroyed, and stock had to be brought to high ground.

The recovery of the paddocks will depend on the future direction of the river as a dam has built up further down.

Murray said some homesteads on the north side of the valley were “completely buggered”, but his family’s wooden house had got off relatively lightly structurally although the inside was a mess. Everyone in the valley had got through unhurt.

The force of the earthquake on valley farmland was “unbelievable” with many slips and it would take farmers a long time to recover as they were still getting through a drought and an earlier flood, he said.

He and his wife Becky were woken up with their sons, Jack and Sam, by the quake in the early hours of Monday morning. Becky was thrown into a window which fortunately didn’t break and they made their way onto a deck.

“The next shake took us from the deck flat on the ground and then we crawled into the middle of the lawn holding onto the lawn and just hung on. Lying on the lawn and hearing the range around us there was just a roar with all the rocks landing on the ground around us.”

Families on the north side of the valley met at the Murray homestead because of the tsunami risk and waited out the morning. Cellphone coverage only returned on Tuesday night and there is no power and piped stockwater remains out from Kekerengu to Clarence which feeds an estimated 60,000 stock. This is a major concern or farmers and will be difficult to repair.

Murray’s surveillance of the area has revealed carnage particularly on limestone land.

“The fault line has gone right up the limestone on the south side of the Clarence and the uplift started from Sandy Bay about 10 kilometres south of the Clarence River and we were standing on the high tide mark and the rocks were about three times above me and they have come straight up from the sea so that’s about 18-20 feet with old man kelp above us and the crayfish and fish were dead on the rocks. So that’s how fast it would have been. It’s come up a limestone spur and ruined one of the most beautiful hills on the south side of the river and further up the river on the Clarence the bridge is completely munted.”

The river has changed channel to flow over the road and over the farmland of Priam’s Flat next to the new hill.

The upper valley bridge was destroyed by the quake while the main bridge has a big lip but can be crossed. The main road further south of Clarence would take “months and months” to repair, however there was road access to Blenheim now for the Clarence Valley farmers.

A two kilometre-long hole is understood to have opened up in the Terehonga area.

The worst part about the quake for the Murrays was that their daughter who was in Culverden did not know if they were safe until Tuesday midday.

Murray said the Civil Defence should have sent out helicopters to check on the safety of farmer families.

His father had told stories of the family camping out on the tennis court for a week or two after an earlier big quake, but they never thought it would happen to them, he said.

From: http://www.stuff.co.nz/business/farming/agribusiness/86519695/quake-carnage-raises-10m-new-hill-at-clarence-river

We’ve been advised that the Clarence River Reserve has been closed due to Fire Risk. Molesworth Station and the Rainbow Road are also closed.