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Water models everywhere, PCE report says – Expert Reaction

A new report says regional councils are often opting to create their own expensive, customised, and single-use freshwater models to help them make decisions when they could potentially be saving time and money adapting already existing models.

Freshwater modelling can help councils make decisions such as how much water to take from a source, but councils are taking an uncoordinated approach to using them, says a new report by the Parliamentary Commissioner for the Environment. The review found at least 75 different freshwater models being used across New Zealand, many of which overlapped in uses. Furthermore, 60% percent of the models evaluated were used only by one council for a single use.

The report makes recommendations for a more coordinated and supportive approach among regional councils to help to turn around the declining state of New Zealand’s lakes, rivers and streams.

The SMC asked third-party experts to comment.

Dr Roger Young, Freshwater Ecosystems Group Manager, Cawthron Institute, comments:

“This review identifies various shortcomings with the way that models are used to assist with freshwater management in Aotearoa New Zealand. These challenges are largely a consequence of the way water management in New Zealand is devolved to regional councils. A lack of national leadership and guidance on model development and use has resulted in multiple models for similar tasks, inconsistencies in the way that models are being applied and the benefits of modelling not being fully realised.

“The review explains the wide variety of model types that can help freshwater management and the wide range of topics where models can contribute. Models can be simple or incredibly complex. Regional differences in climate, geology and land use mean that some models are critically important in some places, but less relevant in others. Models tend to focus on specific topics, such as river flow, water quality, cultural values, and sediment inputs. No single model can do it all.

“Many of the current models used in freshwater management are based on good data but a lack of model transparency and accessibility creates uncertainty and limits use. The review rightly emphasises that monitoring data and models are dependent on each other. It is not helpful to consider that one is better than the other.

“The Commissioner makes some useful recommendations about developing national guidance and support that could contribute to improved freshwater management, although establishing a national freshwater modelling support centre would be a complex task. There are certainly challenges with providing on-going maintenance and support of key freshwater models.”

Conflict of interest statement: “Input from the Cawthron Institute is acknowledged in the report.”

Helen Rutter, Senior Research Scientist, Lincoln Agritech, comments:

“The Parliamentary Commissioner for the Environment (PCE) assessment of the use of freshwater models to support water management in New Zealand examines how NZ uses models and their limitations. We know we need to improve freshwater (groundwater, lakes, rivers, and streams) quality and quantity, but it is a struggle to find solutions – modelling is a way to find those solutions.

“In simple terms, ‘models’ are tools to explore data and enable predictions. They try to predict what may happen when something changes, for example, assessing the effects on water quality from a change in farming practices, or what happens to groundwater levels under climate change. For Cantabrians, a key question could be: ‘What land use changes need to happen to make Coes Ford swimmable

“Models need to be based on existing data and information, and a good understanding of how everything connects. The basic problem is that the real world is far more complicated than a model can imitate, so no model is absolutely ‘correct’, but some are useful!

“The report identifies that although many models are used in New Zealand:

  • some overlap (and may provide different answers);
  • model development is siloed and divided (there is little collaboration between institutions, partly due to the commercial reality of needing to ‘win’ projects);
  • there is no systematic way to determine if the model is fit for purpose;
  • they are not used to their full potential, often used once then not touched again;
  • they are used to suggest a course of action, but not to test whether that was
  • councils struggle to find models of the right level of complexity to answer their questions while being usable and understandable;
  • there is a shortage of modelling expertise and skills;
  • there is a lack of data to base the models on, and lack of full understanding of the complex reality of natural systems;
  • there is a lack of commitment to use models developed by mana whenua.

“New Zealand cannot afford to waste scarce resources on ineffective models. We need a better approach to give effect to the National Policy Statement for Freshwater and protect our water quality and quantity.

“The PCE report recommends there should be a national freshwater support modelling centre to support regional councils, unitary authorities, and mana whenua. Groundwater scientists have been advocating for this for several years, so it is good to see this need being formally recognised.”

No conflicts of interest.

Dr Richard Muirhead, Senior Scientist, AgResearch, comments:

“The PCE’s review of freshwater models makes some important points about barriers that we collectively need to overcome to better manage and ultimately improve our water quality in New Zealand.

“The review highlights the important role of environmental models for informing decision making through the complexity that inevitably comes with issues of freshwater management.

“It articulates some of the challenges facing the regional councils, which are charged with implementing freshwater management policy, and identifies several barriers preventing them from having access to and using the best models. The review also points out that these structural and funding barriers are preventing New Zealand from a achieving a coordinated development and deployment of modelling tools.

“Improvements to models to support the management of freshwater are needed to both attain the water quality New Zealanders desire and demonstrate to our trading partners that our production systems are being sustainably managed.

“As an environmental modeller, it is important to point out that evaluation and improvement of our freshwater models will require more than water quality monitoring data. Freshwater models require inputs of contaminant losses from every type of land use (where that contamination comes from) and how it travels in those rivers.

“To improve our ability to model these processes we will need to collect soil, sediment and contaminant runoff data from multiple land uses and also conduct specific experiments to prove we are modelling in the right way. However, we will only be able to improve water quality when we can demonstrably reduce the environmental impact of our activities in the landscape. Therefore, these activities need to be appropriately represented in the models.

“There is an opportunity in forthcoming Government reforms of the science sector to make changes to the structure of our organisations and funding to remove some of the barriers identified in this report. This will enable the science community to maximise its contribution to the coordinated development of freshwater models that are fit for purpose, as envisioned in this report.”

Conflict of interest statement: “As an environmental modeller, I have been involved in the development, use and review of models for agricultural industries, regional councils and central government.”