Interim Waiohine flood hazard maps now available

Interim flood hazard maps for the Waiohine floodplain will soon be available following their release by Greater Wellington Region Council.

The interim maps model potential flood depths from a large flood, with a one per cent chance of happening in any year, throughout the Waiohine River floodplain and represent a big step forward in building a community consensus around the impact of flooding in the area.

Greater Wellington Councillor and chair of its Wairarapa Committee Adrienne Staples says "these new flood hazard maps represent a marked improvement in the relationship between the Greytown community and Greater Wellington.  While there is still more work to be done before they are finalised, we felt it was vitally important to share the latest information with the community."

GWRC decided to revisit the modelling following an independent audit of the previous flood maps and community feedback on the draft Waiohine Floodplain Management Plan in 2016. This work is being done as part of the wider work of the Waiohine FMP Project Team, which is a community-led process tasked with developing an affordable, sustainable Floodplain Management Plan which is supported by the community.

The new maps bring greater precision to the estimated flood extents through the use of new technology to build a more detailed model, more extensive incorporation of local knowledge, analysis of photographs of historic floods to identify their potential extent and depth, and additional surveying in critical areas.

The preliminary results from the model indicate a significantly smaller flood spread than the previous mapping in use by Greater Wellington and the District Councils.

"The Interim map will make a big difference to a lot of people who live in or want to live in Greytown," says Project leader John Boon. "We have more work to do to finalise a set of completed maps and affordable flood defences but the interim map already means an early and big win for the Waiohine community." 

Final maps will be available following the closing out of the audit and pubic consultation, and are expected to be available later in 2018.

"Final agreement on these maps is critical to the progress of the floodplain management plan," says Cllr Staples, "because we must first agree on what the flood hazard is before we decide how it should be managed. That is the next step in the process of protecting the people and assets of the Waiohine floodplain"

The maps are available on Greater Wellington's website at: http://mapping.gw.govt.nz/GW/Floods/  and he regional council will work with the Waiohine Action Group to inform the community about the interim maps, and full information has been provided both to South Wairarapa District Council and Carterton District Council.