Following the impacts of Cyclone Gabrielle in February 2023 and previous significant flood events, Council is investigating flood resilience improvements across Tairāwhiti.
We're investigating a programme of flood resilience improvements for Tolaga Bay Uawa, Makarika, Tikitiki and Tokomaru Bay.
East Coast catchment areas
Tolaga Bay - Hikuwai and Uawa rivers, Makarika - Mangaheia River, Tikitiki - Poroporo River, Tokomaru Bay - Waiotu Stream and Mangahauini River
This project aims to safeguard lives, protect property and community facilities and improve the resilience of stormwater systems across all 4 catchments.
The focus is on cost-effective solutions to reduce flooding risk to 38 impacted dwellings. 13 dwellings were classified as FOSAL Category 3 and 25 as Category 2 with 14 to be lifted if viable.
Stage 1 is underway. While the project's in its early investigation stage, interventions (all of which consider the PARA framework) are likely to include a combination of:
- stop banks
- hazard mapping
- channel widening/deepening
- attenuation measures
- stream widening
- managed retreat
- capacity improvements at culverts and bridges
*The PARA framework and resilience—each of the 4 main approaches has the potential to contribute to the “big picture” of community flood resilience: Protect, Accommodate, Retreat, Avoid.
What's happening now?
We're at Stage 1
The initial investigations phase - hydraulic modelling and optioneering are underway.
We'll also develop flood hazard maps, sediment models, risk assessments and prepare a cost/benefit analysis for flood mitigation options.
Early engagement with community, iwi and infrastructure owners is underway to share a long list of options for all 4 catchments.
Then the most cost-effective option/s can then be progressed to resource consent, detailed design and construction.
Considerations will include climate change, civil defense evacuation plans, land use, operation and maintenance activities, changes in rivers and interventions to mitigate the risk of flooding.
Programme and costs
Since the start of Stage 1, this has been accelerated by around 3 years by delivering flood resilience projects as solutions are identified and developed rather than waiting for investigations to be completed for all 5 catchments. Acceleration opportunities beyond this are limited due in part to availability of local technical specialists and contractors in these isolated areas.
