Roads will remain closed across the region today as contractors work to assess damage caused by flooding.
Fifty-five local road closures and six on the NZTA state highway network remain closed across the Top of the South on Saturday. But State Highway 60 between the Motueka River Bridge and Riwaka Kaiteriteri Road was reopened at 7.45am.
State highways that remain closed are:
SH6 Belgrove to Murchison
SH63 Renwick to Saint Arnaud
NZTA say there have been further slips on State Highway 6 between Nelson and Murchison meaning the highway closure in this area has been extended.
Significant slips need to be cleared on the Hope Saddle and Spooner’s Saddle, and flooding continues to affect the highway at Kohatu. State Highway 6 is now closed between Belgrove and Murchison.
Motueka River monitored:
While the rain lessened and rivers dropped overnight throughout the district, Civil Defence continued to monitor the state of the Motueka River throughout the night. Of particular interest was the lower reaches, in and around the State Highway 60 bridge.
Recorders on some Tasman rivers recorded the highest flows ever on record.
Overnight the Motueka Emergency Assistance and Information Centre assisted 16 people, housed three and provided alternative accommodation to six others. The number of people who self evacuated to friends and family is unknown.
One home in Grove St, Nelson has been yellow stickered after a slip came down on Friday.
Daylight provides Civil Defence, Councils and NZTA the first opportunity to fully assess damage to property, roads and bridges.
The emergency declaration remains in force.
There are still some areas of concern, and Civil Defence will be flying over a number of areas in helicopters to fully assess damage and to identify areas of immediate need with particular interest in the Motueka Valley.
This event has seen levels in a number of rivers never seen before. It has been driven not so much by the amount of rain but the duration of the consistent rainfall, interspersed by significant bursts.
Resident support
For many residents, it will be the first time they will be able to be fully assess any damage to their properties.
If people have been evacuated, have a welfare need or property has been affected in any way please call the Council on 035438400 Note: If there is an immediate threat to please call 111 in the first instance.
If the house has been flooded keep children and animals away from flooded areas. Do not use electricity or gas until it has been checked and given the ok to use. Before you start cleaning up, take photos of your home and the damage caused as evidence to give your insurance company.
Roads
The roading network including state highways and local roads have been affected. There will be road closures throughout the district and these will remain in place for some time until repairs are undertaken. It is essential that people take notice of and respect the closures in place.
Please limit travel to essential needs only as the roads will need to be surveyed prior to full opening.
What to do after the event
If you require assistance in the immediate aftermath there are a number of agencies ready to assist.
Following the heavy rainfall and flooding we’ve received reports of properties that had buildings flooded. If water goes through a building, it can damage electrical outlets, and damp conditions can potentially cause other safety issues.
If you’ve had water go through your home or other building and need assistance, please call your local council who can send out Building Inspectors to check the structures and give you advice about how to make them safe.
Hydrology Summary
This was a significant event for the Motueka River and upper tributaries. This was attributed to the duration of rain over a 24 to 48 hour period the upper catchments.
Flows at several of the recorder sites were either one of the highest or the highest on record. In the Motueka catchment, Tadmor at Mudstone was the largest flood on record, with records starting in 1978.
Motueka at Woodstock peaked at 1781 m3/s, which was higher than the July 2021 flood (1649 m3/s), and third highest on record, with largest flood recorded in 1983.
In the lower Motueka, Motueka at Woodmans Bend was largest flood on its 25 years of record with 2786 m3/s. July 2021 was 2174 m3/s.
While the impacts were not as severe as in the Motueka Valley, the Waimea Catchment also had significant flows, The lower Wai-iti flow was slightly less than the 1983 flood with 392 m3/s recorded and the second biggest flow on record since commencement in 1976. The Waimea River flow at Waimea at TDC Nursery was the largest flood on its 20 year record with 1475 m3/s recorded.
The rainfall that caused these large flows we saw was due to the duration of constant rain over a 24 to 48 period. In particular, rainfall in the upper Motueka catchment in the Motupiko tributary was a 100+ year event with over both the 24 and 48 hours, with 147 and 214mm recorded respectively.
The rainfall in Richmond foothills around Brightwater and Wakefield also contributed largely to the Wai-iti/Waimea flows. Rainfall at Belgrove was 206mm over 48 hours.
Surface flooding was severe in the lower lying areas and again caused by the 24 to 48 hour rainfall on already saturated ground. The Moutere Valley was one of these areas. Rainfall recorded at Moutere at Kellings was 238 mm over 48 hours, giving a 100+ year return period.
