Flood protection on the Avon

The CCC updated some City Planning Issues information on the 6th of December on the webpage Answers to questions raised at recent Council community meetings referred to in earlier posts.

The bit on flood protection reads as follows:

Inspections and surveys conducted since the earthquake confirm that there are no significant post-earthquake differences in the benchmark levels around the city. This means that the land has not generally risen or fallen with respect to the sea, although there have been minor rises or falls in particular areas.

The lower Avon River has more than adequate capacity to handle a major land-based storm. Flooding risks in the earthquake-affected lower Avon River are mostly related to exceptionally high tide levels which can occur as spring tides and/or storm surges. In general the earthquake has not affected the flood protection status of the river, and the risk of stopbanks overtopping is no greater than pre-earthquake. The stopbanks are strong enough to exclude tidal water. Partial blockages in Porritt Park Loop, Knights Drain and Estuary Drain do not pose a major threat to flooding and are being rectified.

Such issues are much less relevant in the Heathcote River, which does not have significant stopbanks. The area around the Heathcote River was also much less damaged by the earthquake.