Goose Bay is one of the areas that suffered a significant landslide in the quake. Photo/GNS
Goose Bay is one of the areas that suffered a significant landslide in the quake. Photo/GNS
Repairs to South Island stopbanks damaged in the Kaikōura earthquake is expected to cost nearly $700,000.
Work is underway to reduce flooding risk in sites damaged by the earthquake.
Immediate repairs by Kaikōura-based engineering staff began in the week following the 7.8 earthquake, Environment Canterbury's principal river engineer Ian Heslop said.
Since then Christchurch-based river engineers have carried out a detailed damage assessment, and prepared an estimate and works programme for repairs.
"In the Kowhai River, the most serious stopbank damage was at Middle Ford, where the river breached and overflowed through Kaikōura township in 1993," Heslop said.
"The repairs at this location are well advanced, with the most urgent work expected to be completed before Christmas. The total cost of repairs over a 4.5km length of stopbanks is about $690,000."
Heslop wanted to reassure Kowhai River floodplain and Kaikōura town residents that Kowhai River stopbank repairs are being completed as quickly as possible.
By Christmas the most serious sites will have been repaired, with full restoration of pre-earthquake flood capacity expected over the next 12 months.
Further lower priority damage, including the stopbanks between SH1 and the Railway Bridge, Youngs Bank, and Dalzells Bank, are also planned for repair over the next 12 months.
"Residents should also be aware that, although numerous landslide dams have been identified within the Kaikōura and Hurunui Districts, including some minor dams within the Kowhai River catchment, none of these dams pose a flood threat to the Kaikōura township," Heslop said.
There are, however, significant landslide dams in the Hapuku River to the north, and within the Kahutara, Conway, Leader, and Stanton Rivers, and at Goose Bay to the south of Kaikōura.
The Mount Fyffe foothill streams such as the Waimangarara, Luke, and Floodgate Creeks came through the event surprisingly well, although extra gravel input is expected from catchment slips over coming years.
The Lyell Creek channel and floodwall through the township is in good condition, although the stream banks have been badly damaged over a 2km length from near Hawthorne Road to Mill Road. The stream blockages have been removed, but further bank stabilisation work will be needed with an estimated cost of $220,000.
As a precaution, Environment Canterbury strongly advises people to keep away from all riverbeds north of the Waiau River in case there are any sudden releases of water.
