Flood defences

The Bay of Plenty is prone to flooding and one of our core roles at Regional Council is to help minimise the risk this poses to our people, property and livelihoods.

Bay of Plenty Regional Council manages and maintains nearly $440m worth of flood protection defences, including stopbanks, floodwalls, floodgates and pump stations, across five major river and drainage schemes that serve more than 54,500 targeted ratepayers

Our team also develops plans and policies with communities across the rohe, to reduce the impact of flooding. Examples of this work includes Bylaws to protect flood defences and drainage infrastructure.

Technology and monitoring systems that provide the latest information on rainfall and river levels also underpins our work. This is work is managed through our Flood Hub team, who support agencies, such as Civil Defence and Emergency Management, during a flood event.

What our flood defences do

Flood defences are the first line of defence when it comes to helping reduce the impact of significant flooding. Learn more about how they work and what they do in these videos:

Stopbanks

Floodgates

Floodways and spillways

Flood defences in action

Our flood defences operate across four major river schemes and one drainage scheme in the Bay of Plenty. These schemes were established in the 1970s by Regional Council, then known as the Catchment Commission.

The schemes are designated areas of land where we maintain and upgrade flood defences, manage riverbank erosion risks and do drain maintenance.

This map highlights the location of each scheme. Areas outside Council’s River Scheme management and maintenance programme are marked in grey. Out of scheme areas are primarily managed by private landowner/s.

Ratepayers across the region contribute to river and drain management. However, if you live within a scheme, you pay an additional targeted rate.

Flood defences Kaituna Catchment Control Scheme

The Kaituna Catchment Control Scheme covers from coastal areas around East Pāpāmoa and Maketū, through to horticultural areas around Te Puke, and the wider Rotorua area.

Flood defences Rangitāiki-Tarawera Rivers Scheme

The Rangitāiki-Tarawera Rivers Scheme covers the Rangitāiki River with a 3005km2 catchment and the Tarawera River with a 984km2 catchment.

Flood defences Rangitāiki Drainage Scheme

The Rangitāiki Drainage Scheme provides drainage to much of the Rangitāiki Plains.

Flood defences Whakatāne-Tauranga River Scheme

The Whakatāne-Tauranga River Scheme consists of catchments on the Whakatāne and Tauranga rivers.

Flood defences Waioweka-Otara Rivers Scheme

The Waioweka-Otara Rivers Scheme is the smallest of our four Schemes, covering 1,175km2 that extends from the coast at Ōpōtiki up to the regional boundary with Gisborne.

As we have seen throughout history, the results of a significant flood event can be catastrophic to the lives and livelihoods of those in flood-affected areas.

Flood protection is the first line of defence when it comes to reducing the impact of significant flooding. These defences are important as the effects of a changing climate means there is an increased likelihood of more frequent heavy rain events and intense storms, alongside a rising sea level.

Outside Union Bank during the Whakatāne flood, 1948.

Whakatāne flood, 1965.

Flooding on the road to Te Teko, September 1970.

Edgecumbe floods, 2004.

Flooding in the streets of Ngongotahā, 2018.

The ins and outs of flood protection

Flooding is becoming more common in Aotearoa New Zealand and around the world. A common question we get is: how are flood defences designed to perform during a flood?

Floods are measured using Annual Exceedance Probability (AEP) which is the chance of a flood of a certain size happening in any given year. For example, a 1% AEP flood (also called a “1-in-100-year flood”) has a 1% chance of occurring each year. That doesn’t mean it only happens once every 100 years, such floods can happen more often than the name suggests.

A good example of how AEP is used is in the design of stopbanks, raised earth banks that help keep river flood water away from homes, businesses, and farmland. The design of stopbanks depends on the level of flood risk in the area.

There are different types of stopbanks for different settings:

Urban stopbanks, which protect towns and communities, are typically designed for a 1% AEP flood. This higher level of protection helps reduce the risk of major damage to homes, infrastructure, and essential services.
Rural stopbanks, which protect farmland and less developed areas, are often designed for a lower level of flood e.g. 20% AEP flood—a flood that has a 20% chance of occurring in any year. These are generally smaller, as the consequences of flooding in rural areas are usually less severe.

Stopbanks are just one part of the flood protection system. Other defences, such as floodgates, pump stations, and floodways, work together to manage floodwaters and reduce the impact on communities. Engineers design each system based on the specific needs and risks of the area.

However, when a flood is larger than the system is designed for, defences may be overtopped. That’s why emergency planning and community preparedness are an important part to managing flood risk. For more information around how to plan and prepare for natural disaster visit the Bay of Plenty Civil Defence website.

Latest projects

We’re continually investing in and innovating our flood defences, and undertake regular maintenance work to ensure the flood defences are in good condition.

Whakatane–Tauranga Rivers Scheme Safeguarding our stopbanks

We’re doing work to strengthen sections of the stopbank along the Whakatāne River.

Whakatāne - Tauranga Rivers Scheme Project Future Proof

Project Future Proof is a staged project to upgrade flood protection, such as stopbanks and floodwalls, along the Whakatāne town centre stretches of the Whakatāne River / Ōhinemataroa.

Rangitāiki-Tarawera Rivers Scheme Rangitāiki Floodway and Spillway

The Rangitāiki Floodway is a multi-stage project designed to take pressure off the Rangitāiki River in a flood event.

Looking after flood defences long term

The Council is required to implement plans that set out how it is going to ensure flood defences are managed well over the next 50 years.

This asset management plan also highlights how the Council is working to manage issues associated with flooding and drainage, including work on long-term flood defence sustainability and shifts needed due to climate change.