Following the impacts of Cyclone Gabrielle in February 2023, Council is investigating flood resilience improvements across Tairāwhiti.
The Gisborne city area was severely impacted with more than 170 homes flooded, 48 dwellings classified as FOSAL Category 2 with 24 being lifted if viable and 14 impacted due to land instability. To address this, we're currently investigating a programme of flood resilience improvements.
Gisborne city
Taruheru, Waimata and Turanganui rivers
This part of the project involves flood resilience improvements for the Waimata, Taruheru and Turanganui rivers.
The project will identify and deliver cost-effective interventions to reduce the risk of inundation to around 100 dwellings across the Gisborne city catchment.
It aims to safeguard lives, protect property and community facilities, and improve the resilience of the city's water, wastewater, and stormwater systems.
What's happening now?
We're at Stage 1
This is the investigations phase - completing hydraulic models, identifying constraints in the piped and waterway network, pinpointing secondary flow paths and a cost/benefit analysis for flood mitigation options. It also includes consultation with the community, iwi and infrastructure owners over the mitigation options. The most cost-effective option/s can then be progressed to consent, detailed design and construction.
The design service level will be equivalent to a 1:100-year event with an allowance for climate change and sea level rise.
Considerations include climate change, interaction with the stormwater network, land use, current assets, changes in the river and interventions to mitigate the risk of flooding from the 3 city rivers.
While the project's in its early investigation stage, interventions may include stopbanks, channel widening or deepening, capacity improvements at culverts and bridges and or piped network upgrades.
River dredging is also being investigated.
Stage 2 is being finalised and expected to start in late-2025 and mid-2028.
Estimated cost $13.95m.
