Clean-up crews drowning in work

Slips, river erosion protection works, ripped out, blocked rivers, river channels o course, debris and silt buildup, river ood capacities compromised.

Across the Waikato region, the estimated cost due to damage from the ooding events is nearly $18.5 million.

All areas presenting immediate high risk of ooding to communities and properties are being done as a priority before June 2023 with further remedial work to continue in the following two years.

One job of high priority is remediation works to the Ohinemuri River in Paeroa, beneath the Criterion Bridge, currently underway. e river, the largest tributary of the Waihou River, is part of the Waihou Valley ood protection scheme.

Works supervisor Hayden McGregor says major silt deposits accumulated on the inside corner (south side) of the river under the bridge during the oods signi cantly reduced the volume of water that could pass under the bridge.

“As a result of the river having to make room for itself, it eroded a lot of the river berm in the front of the stopbank that protects the town. So, we’re creating some rock armouring to the riverbank to prevent any further erosion and loss of bank.”

Up to a metre of silt was also removed from the surface of the berm on the downstream, south-side of the bridge to improve future ood capacity of the river within the town’s two stopbanks. e unseasonably wet summer caused extensive damage to multiple rivers and streams in the Coromandel Peninsula and Hauraki catchments, and to a lesser extent in the lower Waikato/ west coast.

Cleaning up has been the immediate focus of the council’s river management teams, so removing trees from the rivers as they cause blockages that exacerbate damage, and realigning river channels.

Coromandel Catchments lead James Ferrier-Kerr says the events of the summer have culminated in the worst, widespread damage he has experienced in his seven years working in river management in the peninsula.

“A big part of the Coromandel story is the successive heavy rain events we’ve had in May, July, September, November, December, followed by Hale, Auckland Anniversary weekend in January then Gabrielle for three days in February,” says James.

“When Gabrielle made landfall, we were already in a state of catchment saturation with obstructions and bank erosion sites known but unable to be remedied between events. Since Gabrielle, we continued to have localised heavy rain in March and April.”

James says the priority has been clearing obstructions to mitigate the ood and erosion risk before starting on erosion protection works.

“We estimate a further 12 months of remedial works.”