North Shore Times (New Zealand)
Drones set to monitor city’s landslides
Drones will be launched into Auckland’s skies to measure how far the city is moving during landslides.
A University of Auckland study funded by EQC to the tune of $45,000 will use drones to monitor landslides on 10 slopes across the city for two years.
Most of Auckland is at risk of landslides with many of the city’s houses located close to slopes with a history of sliding after periods of rainfall according to Dr Martin Brook of the University of Auckland who is leading the project.
Drones will take pictures of the slopes, creating 3D computer models of the land.
Those models will be compared with older ones, created through slower and more expensive methods involving helicopters and lasers, to see how far certain points had moved over the years.
Rain is the major cause of landslides in Auckland, Brook said. Last year Auckland received a year’s worth of rainfall in the first nine months.
Auckland was peppered with ‘construction fill’, construction material and dirt shovelled into the ground, that made it vulnerable to rainfall.
Rainwater seeped into construction fill causing it to move, sometimes dramatically, as with a North Shore parking lot last year, Brook said.
In other cases houses lay within sites of known historic landslide zones such as the Pourewa landslide zone, which includes the suburb of O¯ ra¯ kei, the site of four historic landslides.
‘‘The slopes are always on the move, it’s that simple.
‘‘It’s not like these landslides occurred a few thousand years ago and never occurred again. In Auckland it needs to be taken a bit more seriously.’’
NOTABLE LANDSLIDES IN AUCKLAND
* Kohimarama apartments (2017) - A landslide after intense rainfall during Cyclone Debbie in April last year caused a wall of mud to smash into a block of flats in Kohimarama leaving emergency services desperately trying to account for residents.
* Rawene car park, Birkenhead (2017) - What started as a crack turned into a major slip that saw part of a car park fall away last year.
* Torbay, North Shore (2008) - 63mm of rain fell over two days in Torbay causing a slow-moving landslide that destroyed a North Shore home and placed another 14 homes at risk.