Under water: A 1999 flood saw Lake Whakatipu inundate the lower margins of Glenorchy. PICTURE: OTAGO REGIONAL COUNCIL


Otago Regional Council is eager to begin a ‘‘dialogue’’ with Glenorchy residents following the release of two council-commissioned studies detailing the township’s natural hazards.

New evidence from investigations into liquefaction and flooding scenarios confirm a moderate to major earthquake or flooding event in GY could have severe impacts on people, property and infrastructure.

Council’s data and information committee chair Alexa Forbes says the new information could be confronting for residents, particularly those new to the area who may not be aware of the liquefactiondanger.

‘‘Of course, these hazards are only potential, but we know AF8 is overdue and we need to prepare … [the reports are] giving people the information that they need, so they can
think about how they might prepare for the potential hazards.’’

One of the reports by geotech consultant Tonkin + Taylor found there’s a thick layer of delta and alluvial sediments under the township that would likely liquefy, lose strength, and slide if shaken by a strong earthquake.

As the township has a greater thickness of liquefiable sediments, and a drop of 25 metres into Lake Whakatipu, the report says the impacts of an earthquake in GY may be worse than the most-affected areas of Christchurch during the 2010-’11 quakes.

An assessment by Land River Sea Consulting Ltd into flood hazards for the Dart-Rees floodplain found the worst scenario would result in the township being unsafe for vehicles and people, buildings may be vulnerable to structural damage, and large sections of Kinloch Road and the Glenorchy-Routeburn Rd would be inundated.

There’s already been an online community briefing and more meetings are planned, but Forbes encourages people to ask questions and share concerns.

‘‘We’ll see what support’s needed, what people want to do, how they feel about it — it’s pretty much just the start of an ongoing dialogue.

‘‘We won’t always know the answer straight away, but we will seek those answers out.’’