SYDNEY, April 19 (Reuters) - A clean-up began in New Zealand's capital Wellington after flash flooding, sparked by heavy rain, hit the nation's North Island, authorities said on Sunday.
"Severe weather has caused flood damage across the city," said Hutt City Council, a government authority within the Wellington region, which has a population of 520,971.
"We know many people across Lower Hutt are dealing with flooding impacts and debris," the council said, adding that crews were in the field cleaning up "hardest hit areas" in the suburb of Stokes Valley.
A state of emergency was declared in the Whanganui District 150 km (95 miles) north, and 18 people were evacuated due to flooding, public broadcaster Radio New Zealand reported.
The nation's weather forecaster predicted more thunderstorms, accompanied by very heavy rain, for parts of the North Island including Wellington on Sunday.
"These severe thunderstorms are moving towards the southeast," it said.
The wild weather, which sparked evacuations on Saturday, follows the island's battering a week earlier by Cyclone Vaianu, which forced residents to higher ground.
(Reporting by Sam McKeith in Sydney; Editing by William Mallard)
