Options for reducing the flood hazard on the lower Taieri are to be considered by the Otago Regional Council.
A report to be presented to the council's engineering and hazards committee tomorrow outlines four options developed as a result of a reviewof the Lower Taieri River Flood Protection Scheme and an associated flood hazard study.
Residents of the area have been waiting for the outcome of the review and study since the area was hit by severe flooding in April 2006.
Flood risk had changed little for most of the western part of the Taieri Plain, except Dunedin International Airport and Outram, but was more pronounced for the eastern part of the lower Taieri flood plain, where the development of urban subdivisions and lifestyle blocks had occurred to the west of Riccarton Rd.
The 2006 flood showed the source of flood water was more from the Silver, Owhiro and Mill Streams than the Taieri River, the report said.
Models were used to simulate various-sized floods and to test the lower Taieri flood protection scheme.
Four options were tested against 200-year and 500-year floods and the April 2006 floods:
1. Widening of the Silver Stream corridor from Gordon to Gladfield Rds.
2. Providing a new spillway on the left bank of the Silver Stream between Riccarton and Gladfield Rds.
3. Providing a bunded storage area alongside the existing Gordon Rd spillway on Silver Stream.
4. Moving the existing right bank spillway at Gordon Rd to spill more directly to the upper ponding area.
However, options 1 and 3 were both likely to be expensive to construct and involved buying land, so options 2 and 4 were seen as having the "greatest potential'' for implementation, the report said.
"It is likely that the final preferred option for the mitigation of flood hazard on the East Taieri flood plain could be a combination of the various options.''
There was also the possibility of designating flow paths that would need to be kept free of obstruction and further development.
Results of the scheme analysis now needed to be considered in detail, it said. The draft 2008-09 annual plan provided for continued investigation of the options, or a combination of them.
At tomorrow's meeting, councillors will be asked to note the review and to recommend the Mosgiel Taieri Community Board be briefed.
