Drone delivers grim images of water catchment damage
Massive landslips and swathes of destroyed native bush have been discovered in the Hunua Ranges following the storms in early March, with Watercare warning they pose a further threat to the city’s fragile water supply.
The scale of the destruction caused by the storms on March 7-8 has been revealed in drone footage and pictures taken by Watercare.
Imagery captured on Tuesday shows slips hundreds of metres long tore through commercial forests and native bush in the Hunuas in southeast Auckland during the massive flooding event, which meteorologists have dubbed the “Tasman Tempest”.
And prolonged rainfall expected over the next week means waterlogged soils are poised to dump further silt into Auckland’s water supply.
Watercare chief executive Raveen Jaduram said the video footage was very concerning.
“With large areas of exposed soil and water-laden earth, further rainfall elevates the risk of more silt washing into our water supply dams.”
Rain is likely over much of the North Island on the weekend, with the possibility of heavy falls on Sunday in Auckland and rain continuing through till Friday next week.
Between March 7-12 the Hunuas received more than two-and-a-half times as much rain as fell during Cyclone Bola.
Watercare and Auckland Council
were looking for ways to manage the slips and protect the dams, Jaduram said. He is asking Aucklanders to keep saving water in light of issues at the Ardmore treatment plant, which is still running well below treatment capacity due to excess silt in the storage dams.
In the days following the downpour, Watercare called for Aucklanders to cut their water use by 20 litres per day, to avoid the company being forced to supply partially treated water, which would need boiling before use.
By March 15, water supply was stable.
The volume treated at Ardmore has climbed by 30 million litres a day over the past week, but silt levels remain extremely high, Jaduram said. With more rain on the way, the plant’s output will not be increasing further this week.
That meant people still needed to save 20 litres a day, he said. In the past seven days Auckland used an average 404 million litres a day — slightly over the target of 400 million litres.
Businesses normally ramp up their water use midweek, but on Tuesday — which was World Water Day — usage was still only at 406 million litres.
Children at Lollipops Educare in St Lukes celebrated World Water Day by colouring with pens instead of watercolours and using leftover drinking water on plants.
Jaduram said it was “heartwarming” to see Aucklanders’ response.
“We’re a big city and yet we’re proving that in times of need, we can come together and do our bit to preserve the health and wellbeing of our diverse community.”