How did Méthod’O come into being? Through Artelia’s innovation work, or to meet a need on a specific project?
Both. There is an abundance of literature, international agreements and regulations on the green transition, all saying that a change of method is essential and that conventional planning and development practices are inadequate but without proposing new ones. Here at Artelia, we have been wondering for some time how things could be done differently, and exploring various possibilities. Meanwhile the Greater Reims urban area authority, which is subject to frequent flooding, was also looking for an innovative approach to update its rainwater management master plan. Méthod’O is the result of the two coming together.

What is it for? How does this method differ from the conventional approaches?
The goal is to find sustainable solutions for adapting to climate change by shifting to a regional ecosystem approach and implementing a collaborative process involving all the stakeholders within the region concerned. For Greater Reims, for instance, even though the primary aim was to reduce flooding, we didn’t just work with the rainwater management department and model runoff, discharges and depths of water, which is what a conventional approach usually entails. We broadened our vision to include the entire ecosystem contributing to water management and, most importantly, we called in all the stakeholders to help them articulate and rank their priorities, and set meaningful indicators and targets.

How does it work in practice?
Méthod’O has two components: the process and the tool box. The process consists in consulting the stakeholders concerned by the topic, to pinpoint their expectations and gather their opinions. We conduct interviews and organise workshops, which are also opportunities to educate these players on subjects such as climate change issues and today’s sustainable development solutions. We then analyse their responses and come up with definitions and objectives that everyone agrees on. By adopting this focus, we can then build representations of the region that match their vision and help them with decision-making in very practical ways.

The tool box contains both consultation resources to be used during the collaborative process and sophisticated technical tools for managing and modelling data and displaying it in the form of maps and graphics. For instance, we have created a fun, informative card game to help interviewees

formulate their priorities in a simple way. This gives us standardised, usable data. It can also be used for educational purposes. We have also developed a very powerful modelling tool, called ORus, dedicated to managing rainwater at source.

How was the process implemented for the Greater Reims rainwater management plan, and what was the outcome?
We put the question “What does rainwater management mean for you?” to about 200 stakeholders including elected officials, staff at local authority technical departments, institutional partners such as water authorities, the regional natural park, the chamber of agriculture, the union of Champagne wine professionals, and civic associations. This work enabled us to build a consensus around five ecosystem indicators that reflect the local authority’s ambitions on the subject of rainwater management:

• protection of people and property;
• quality of water bodies;
• support for biodiversity;
• living environment;
• land footprint.

These indicators, rated from 0 to 5, are now being used to guide its actions and assess the pertinence of planned developments. Each year the Greater Reims authority is also able to assess, at a regional scale, whether the solutions rolled out have led to an improvement in the situation.

Coming back to the tools, can you tell us more about the ORus model you mentioned for managing rainwater at source?
t’s what we call a “hydrological model with a susceptibility score”. Construction of the model has formed the subject for a thesis which I am due to defend in 2024 at the Université Grenoble Alpes with support from Artelia and the Inrae, the French National Research Institute for Agriculture, Food and Environment. This model indicates, on a square metre scale, the intrinsic susceptibility of the region to generate runoff, whatever the rainfall. It considers soil permeability in particular, and identifies areas that will produce a large quantity of water while simultaneously calculating accumulation from upstream to downstream.

This model is the only one of its kind that functions at this geographical scale, and it was successfully used to eradicate the flooding that occurred regularly on avenue Jean Jaurès in Reims. ORus was used to identify the problem areas and implement targeted actions there, proposing a range of nature-based solutions to manage rainwater at source (increasing soil permeability, restoring plant cover, etc.). For avenue Jean Jaurès, rather than building an underground storage tank beneath one of the city’s busiest squares, we were able to solve the problem by eliminating the flooding at source for a tenth of the cost.

Using this ecosystem approach, backed up by some top-flight scientific and technical knowledge and tools, we were able to find sustainable solutions in cases where conventional methods had failed.

This ecosystem must call on a wide range of skills. How did you pull them all together?
One of Artelia’s strengths is having a very wide range of expertise within the Group. More than 14 people were involved in designing Méthod’O, including Édouard Rousselle (urban planning engineer), the project’s co-leader Natassia Chylak (regional management engineer), Aurélie Paillet (environmental regulations engineer), and Aurore Zeller (agronomist). This wide range of profiles was vital to create Méthod’O.

Is it a method focusing on runoff and flooding issues, or is it intended to become universal?
We are currently using Méthod’o and its tool box to help other regional authorities with runoff and flooding issues. For example, ORus is being applied to the Eurométropole Metz urban area, where it is providing additional information on the intense runoff that occurs in the Saar river basin. There are also plans to use it to assess the vulnerability of the areas of northern France that were severely affected by the storms of November 2023.

At the same time we also want to make Méthod’o a green planning tool that can be applied to other issues related to climate change and biodiversity conservation. We are studying the possibility of adapting it to droughts and heat islands; in fact, Artelia is supporting a new thesis in this area.

With this ecosystem approach and collaborative process and an expanded tool box, we are also looking to address topics such as increasing soil permeability (in line with France’s zero net land take policy), creating blue and green corridors, developing coastlines, and reducing susceptibility to wildfires. We have already started applying Méthod’o and ORus to soil permeability restoration issues in the urban areas of Esterel Côte d’Azur and Béziers. And several other projects are in the pipeline.

To sum up, what are the key strengths of Méthod’O?
By adopting an ecosystem approach, Méthod’o answers the fundamental questions of land-use planning: where to act, what to do, and to what performance level? It does not systematically replace traditional studies; rather it provides a means of targeting them more precisely and investing public money as efficiently as possible. It offers both regional players and planning engineers a different perspective, helping them to act differently, in practical ways, to build sustainable regions.