Parts of coastal hazards report deemed 'misleading'


Following the Tonkin and Taylor report, the council was required to put coastal hazard information on Land Information Memorandum reports. Anstiss said that information would remain on LIMs at this stage. The council would thoroughly review the final report's findings before any decisions were made surrounding the LIM information. 


[221] Thus, for the time being, the conclusions in the first and second stages should not extend to firm hazard lines designed to go into the LIM reports or for inclusion in the CRDP as maps or zones.



A controversial coastal flooding and erosion report took only 20 days and aspects were "misleading" and "not fit for purpose", a panel of scientific experts has found.


The panel identified a series of shortcomings after it was set up to provide the Christchurch City Council with an impartial view on a report that identified thousands of properties could be susceptible to erosion and coastal inundation.


But, the overall Tonkin and Taylor Coastal Hazard Assessment Report was deemed fit for purpose by the panel – only once certain changes and calculations were made.


Changes recommended by the panel could see some coastal properties deemed no longer at risk of erosion, but still at risk of being inundated. It was not known how many would be affected.

The panel acknowledged the Tonkin and Taylor report was undertaken in a tight time-frame with limited budget. 


"In these circumstances, to meet time and budget constraints, simplifying assumptions could be expected." 


Tonkin and Taylor's report, released in July 2015, identified 6000 Christchurch properties that could be susceptible to erosion and nearly 18,000 at risk of coastal inundation over the next 50 to 100 years.


The science behind the report has been widely questioned and in December the council decided to subject the document to a second peer review, which has cost the council $168,650. The first peer review cost $3200.


The panel's draft report, released on Tuesday, said the coastal erosion hazard zone for all harbour sites, including the Avon-Heathcote Estuary and Brooklands Lagoon, were "not fit for purpose, are misleading and should not be considered as indicative of likely erosion hazard".


"It is recommended they be re-assessed with more attention to detail and on-ground inspections," the panel said.


Tonkin and Taylor natural hazards business leader Richard Reinen-Hamill said on Tuesday that he stood by the report, but accepted the panel's recommendations.


"I feel we have done a pretty good job."


He said he was given 20 days to complete the report and given more time, the company would have been able to refine aspects to give greater clarity and accuracy regarding some definitions.

Reinen-Hamill said changes recommended by the panel regarding the erosion zones would mean fewer properties would be eroded, but they could still become inundated. 


He said the overall number of properties affected by erosion and inundation would remain unchanged. 


Christchurch Coastal Residents United (CCRU) member Warwick Schaffer​, who was a member of the community reference group which determined the panel's makeup and terms of reference, said the group had several questions regarding the panel's findings, including its apparent acceptance of a 1 metre sea level rise over 100 years.


Council strategy and transformation general manager Brendan Anstiss​ said the council had been working to the truncated timeframes of the district plan review, but a significant amount of the work for the report had already been completed in two previous coastal hazard reports completed from November 2013.


He said the council received the draft report late Monday and staff and councillors were reviewing it to see if it would seek any points of clarification from the panel.


Following the Tonkin and Taylor report, the council was required to put coastal hazard information on Land Information Memorandum reports. Anstiss said that information would remain on LIMs at this stage. The council would thoroughly review the final report's findings before any decisions were made surrounding the LIM information.


The council, Environment Canterbury and the Community Reference Group have until August 8 to raise any points and the final report will be discussed at the council's August 25 meeting.


The panel experts include retired Environment Court judge Shonagh Kenderdine, New South Wales University coastal engineer Ron Cox, Canterbury University coastal studies senior lecturer Dr Deirdre Hart, Waikato University earth sciences senior lecturer Dr Willem de Lange, and statistician Dr Murray Smith. 



By the numbers


20 days given to complete the Tonkin and Taylor report

$168,650 cost of the second peer review

$3200 cost of the first peer review

6000 properties susceptible to erosion

18,000 at risk of coastal inundation




This article appeared in STUFF

view the original article here






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