Murihiku Slow the Flow Upper Mataura Pilot
The Murihiku Slow the Flower Upper Mataura pilot is funded by the Ministry for the Environment and will finish in June 2025 when the results of the pilot will be available to help inform future conversations around flood mitigation.
The pilot will take modelling into the field, to see how the flood reduction benefits of four nature-based solutions work in real-time and see which may be suitable for wider roll-out.
The Upper Mataura catchment was chosen after extensive flooding in early February 2020 resulted in the evacuation of more than 4500 people from their homes.
Reducing the peak flow of the Mataura River, also reduces the current flood risk to Gore and Mataura and future increased risk to the townships due to climate change.
Toitu to marae o Tane
Toitu to marae o Tangata
Toitu to Iwi
When the land and waters are strong, so are the people
Regular updates about the project will be posted here. If you want further information about the project contact Ella Lawton, ella.lawton@es.govt.nz .
Flood Risk Management
Traditional flood risk management considers two elements – structural and non-structural.
Structural methods involve physical changes such as dams, stop banks and floodways. They also include natural and nature-based methods, like vegetation/wetlands, soil health and water retention.
Non-structural measures, on the other hand, seek to change social conventions. That includes things like include policies, regulations, social institutions, organisations or individual behaviour, and alert systems.
Stage One
It is hoped the project will help shift the conversation, to redefine the problem and source solutions beyond ‘hard infrastructure’, toward an integrated approach for long-term success.
The proposed structural nature-based solutions are: The Project Execution Plan is available here.
It is hoped the project will help shift the conversation, to redefine the problem and source solutions beyond ‘hard infrastructure’, toward an integrated approach for long-term success.
The proposed structural nature-based solutions are:
Nature Based Solution | Benefits |
Detention bunds | These can often be constructed without needing resource consents (For example, bunds less than 3m high, catchment less than 50 ha) which makes them lower costEnable productive land-use between eventsCan achieve both water quantity and quality (reduced sediment, particulate and faecal microbe) controlCan be targeted to manage localised gullying, bank erosion and floodingCan provide water for stock, firefighting, and irrigation in rural areasCan provide water for non-potable uses in urban areas such as for passive urban cooling |
Constructed wetlands | Potential to design for specific storage targetsCan be sited in strategic locationsProvide wide range of co-benefits, including contaminant reduction, habitat, and biodiversity, mahinga kai, aesthetics, culturalLess expensive than conventional wastewater treatment options |
Vegetation, i.e., tussock | Landcover change can be used to increase infiltration, canopy interception and evapotranspiration and thus reduce magnitude and temporal response of flood peaksForest cover can provide carbon-sinks for carbon sequestration.Green corridors and similar can lead to habitat creation and passage for birds and fish and improvements in water quality (e.g., biodiversity, visual clarity, etc) |
Room for the River | Increased stormwater storage and conveyance capacity in system (flood plain, stream courses)Encourages greater biodiversityCan become self-maintainingAesthetic value increasedPossible improvements to water quality and ecosystem health |
There is more information about these nature-based solutions in a NIWA Literature Review (May 2024).
The project is keen to work with Catchment Groups and landowners in the Upper Mataura, so we can better understand the opportunities and limitations of nature-based solutions within the farming system.
In return the Catchment group will benefit from having flood modelling completed for their catchment, and an opportunity to influence future floodplain management in Southland. A summary of the technical framework to date is available here.
