The impact of flooding on property values, the ability to insure homes and emergency access via State Highway 6 are among concerns raised by new studies, residents say.
Flood modelling of Brightwater and Wakefield indicates sections of SH6 and the lower areas of Brightwater's residential area and the town's industrial zone will be at risk of inundation in a 1:100 year event.
A 1:100 year flood is defined as having a one in 100 chance of happening every year.
The modelling work by consultants Sinclair Knight Merz ( SKM) was commissioned by the Tasman District Council so it could understand and respond to the risk.
The 35-page report just just been publicly released and will be followed up with community meetings in February.
Wakefield Community Council chairman Allan Walsey said residents were aware the modelling had been done because the results were being noted on the Land Information Memorandum reports of affected properties.
He said residents had not yet seen the report but were aware severe flooding would have an impact on Wakefield, but Brightwater would suffer worse.
"One of the major issues is the ability of all affected property owners to insure their homes. Another is concerns around safe emergency access on the state highway." The resulting value of flood-prone homes was also likely to be affected, he said.
"But from a community point of view the big concern will be safe access both in and out of the towns."
In the case of Wakefield SKM predicted a 1:100 event would see most of the flooding from the Wai-Iti River occur on agricultural land but some parts of SH6 would be inundated and water would flow over Pigeon Valley Rd north of the bridge at 70 litres a second and to a depth of 300mm, which could endanger vehicles.
Flooding from 88 Valley Stream would also push spilled water along the south side of the disused railway embankment, over 88 Valley Rd, down through Faulkner Bush and into the township at a rate of about 1.5l/s and to a depth of up to 200mm.
Water from Pitfure Stream catchment would also impact on the sports field and parts of the end of Wanderers Rd.
However parts of the floodplains around Brightwater will be under a metre of water in a 1:100 year event and significant sections of SH6 will also be impassable. Floodwater will endanger the town's raised industrial area.
Water from the Mt Heslington Stream, which passes through the town, is predicted to put a number of homes and businesses, particularly around Ellis St, Waimea West Rd and the lower sections of Malthouse Cres, at risk.
Brightwater Community Association chairman Andy McQueen did not want to comment until he had seen the report.
Council spokesman Chris Choat said the council would provide the residents with results of the flooding hazard modelling which was commissioned to help inform planning, infrastructure and emergency management decisions.
The findings showed that a 1:100 year flood would only affect very limited areas of the residential development and some industrial development and confirmed the areas that are flood prone, the extent of the flooding in those areas and what might be expected in the future as climate changes occur.
The modelling results will be presented at meetings, for discussion with the Brightwater and Wakefield communities from February, he said.
- © Fairfax NZ News
Should the Nelson City Council spend up to $500,000 to fix the modellers' pond at Tahunanui?Related story: (See story)