The front-page article last weekend prompted me to think about home buyouts versus flooding mitigation.
Since my previous submission on flooding issues, I have learned that the water level upstream of the log dam on the Gladstone Road Bridge reached 2.8m against the NZVD (mean sea level) datum. To put that into perspective, that is equivalent to about 100mm of water over the Eastland Port log ship berths.
While the lower reaches of the Taruheru (approx. Oak Street to the Marina) have more than adequate width for its catchment flows, it is the water level in those lower reaches, backed up behind the debris dam on the Gladstone Road Bridge, that obviously caused the flooding of properties along the banks of both the Waimata and Taruheru rivers —right through the city and out past Makaraka to around Tucker Road up the Taruheru.
That woody debris dam raising the upstream water level to 2.8m is clearly the cause of the damage in Anzac Park, to the properties in Grant Road and Marion Drive, the St John base in Bright Street, lower Grey Street, Thomson Street and Ferguson Drive, and the cause of the need for property buyouts and compensation to the owners.
How much of that damage, disruption and cost to property owners, ratepayers and taxpayers could have been avoided by earlier deployment of the port equipment on to the Gladstone Road Bridge to start clearing the whole trees and longer lengths of timber from the water, thereby reducing the water level back-up to maybe 2.0m?
