Flooding, foothill rivers, coastal update South Canterbury

On top of the recent severe weather warning, the Metservice has issued a coastal swell warning for the east coast, says Environment Canterbury’s Timaru-based Flood Controller Malcolm Miller. The easterly swell, rising to 3.5 – 4 metres this evening could potentially block off river mouths and overtop onto land, he says.

The high tide around 1 am Wednesday morning is when the swell is most likely to overtop and block river mouths. The areas likely to be affected are from the Waitaki River to the north of Timaru.

Periods of heavy rain are expected through to Wednesday afternoon. In the 24 hours from 3 pm Tuesday to 3 pm Wednesday, the Metservice says to expect a further 80-120 mm of rain about the hills and ranges, with 30-50 mm about low-lying areas.  Between 60 and 120 mm of rain has already fallen in different parts of South Canterbury more more intense falls around Waimate. At Morven, south of Waimate more than 80 mm has fallen since midnight last night.

Further rain intensities of 6-10 mm an hour are likely with bursts of 10-15 mm an hour are expected about the hills and ranges overnight.

The freezing level is 1500 metres overnight.

With the land soaked from the past two days steady rainfall, some foothills rivers have shown sharp rises this afternoon, Mr Miller said. The Waihao River at McCulloughs Bridge had risen to 390 cumecs (cubic metres of water per second) around 5pm and the Maerewhenua, near Duntroon on the south side of the Waitaki River, dropped slightly to 223 cumecs.

Earlier advice to farmers to monitor their local river situation closely and to move stock from low lying areas remains in place.

Environment Canterbury will continue monitoring rain and river flows from its network of rain and river flow recorders and advising local emergency services and Civil Defence Emergency Managers. The Environment Canterbury Timaru Flood Room will be open overnight Tuesday.

For more about the latest river flows call the Environment Canterbury 24 Hour River Report Info Line 0900 RIVER (74837). Charges do apply.

Or you can check river levels and rain recorders:

http://ecan.govt.nz/services/online-services/monitoring/river-flows/Pages/River-flows-south.aspx

http://ecan.govt.nz/services/online-services/monitoring/river-flows/
http://ecan.govt.nz/services/online-services/monitoring/rainfall/

Maerewhenua River:

http://ecan.govt.nz/services/online-services/monitoring/river-flows/pages/river-flow-chart.aspx?SiteNo=71106

Waihao River at McCulloughs Bridge:

http://ecan.govt.nz/services/online-services/monitoring/river-flows/pages/river-flow-chart.aspx?SiteNo=70902

Rain radar map:

http://www.metservice.com/national/maps-rain-radar/rain-radar/all-nz-rain-last-6-hrs or for general forecasts www.metservice.com

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