South Canterbury could see torrential rain and surface flooding for the second time in as many weeks, according to a severe weather warning issued by MetService.
Starting at about 9pm tonight, as much as 140mm of rain is expected to fall in the foothills, with falls up to 100mm near the coast.
The rainfall will bring ‘‘almost certain surface flooding,’’ Environment Canterbury said in a news release.
The heavy rain is expected to affect South Canterbury and northern Otago through much of Wednesday.
Residents should be aware that the rain could bring high river flows, full culverts and surface flooding to the region, the Timaru District Council and Civil Defense warned. Local community Civil Defense volunteers are on standby, and ECan’s Timaru flood control room is ready for action, said Duty Flood Control Officer Tony Henderson.
“This is a very similar amount of rain to that experienced last week and is coming from the same easterly direction,” Mr Henderson said. “This means that we could be facing similar river flows to those we were dealing with last week, which saw rivers reaching between 10 and 50-year flows.”
The ground is still saturated from the up to 240mm of rain that fell in last week’s storm, which could add to the problem, he said.
Farmers are warned to move stock to higher ground and residents living near rivers are advised to remain vigilant.
“With the ground already so wet, there could be significant extra run-off which means rivers could rise very quickly,’’ Mr Henderson said.
If heavy rains arrive as expected, residents are asked to avoid unnecessary travel, especially at night. People living in flood-prone areas should prepare emergency kits and know how to evacuate if asked to do so.
Last week’s 36 hours of torrential rain left behind extensive damage to rural bridges and surface flooding throughout low-lying areas.
The downpour on July 31 caused significant damage to roads and left several residents isolated. Some roads were washed out with access limited in the Mackenzie district, where five bridges lost approaches.
Raincliff Bridge near Pleasant Point was closed when contractors discovered the middle of the bridge had dropped 200mm.
Timaru, Mackenzie and Waimate councils all reported extensive scouring on the roads. Mackenzie was significantly affected, with residents isolated by flooding in the Haldon area.
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