Environment Waikato is starting emergency repair and reinstatement works on the Tongariro and Tauranga Taupo rivers following last month’s flood.

The damage caused by the floods on both rivers happened in areas where work was not yet in place, rather than because stopbanks failed.

On the Tongariro river, the flood, one of the largest on record, had a peak flow of 1400 cubic metres per second (cumecs) which represents a one-in-100 year event. The last time a flood of this size occurred was 1958.

In the urban area of Turangi, homes were inundated and the flood damaged some existing works, including stopbanks and rock protection. This included the stopbank at Tahawai Street, and the rock work off the end of Herekieke Street. Considerable numbers of logs, other vegetation and debris were deposited throughout the river channel.

Environment Waikato is in the final stages of confirming the comprehensive programme of river management and flood protection for the river, which is waiting on the granting of consents. Work was expected to start just as the flood struck, Project Manager Bruce Peploe said.

“Because of the damage caused by the flood, urgent works are needed and these will commence later this week under the emergency provisions of the Resource Management Act. Works will be undertaken to clear the river channel in certain places, rock protection works will be repaired, and some stopbanks will be raised.”

Damage on the Tauranga Taupo River happened near the end of a programme of works that would provide better management of the river and improved flood protection for the settlements of Oruatua and Te Rangiita, he said.

The works completed included stopbanking, the Kiko overflow channel and a closure structure to prevent flood waters from flowing into the quarry above the settlements.

“Although some damage occurred to these works this was minimal. The most significant effect of the flood was some localised flooding near the State Highway at Te Rangiita. This was caused by the fact that the stopbank in this area has yet to be constructed,” he said.