TONIC: Tools for Green Resilient Cities

Coordination :

• INRAE, REVERSAAL, Villeurbanne. Contact: Pascal Molle - pascal.molle@inrae.fr

Active period :

2020-2024

Financing and parteners :

• French Office of Biodiversity: 19.3%
• RMC Water Agency: 18.1%
• AG Water Agency: 18.1%
• EUR H2O: 9.6%
• INRAE: 24.6%
• INSA Lyon: 10.8%

Background:

Urban areas are coping with challenges tied to changes in water and land management strategies resulting from the increase in urban population, climate change and the need to develop an efficient economic environment. Climate change induces a rise in the frequency of extreme events, like floods, heat waves, drought and storms, which in turn place added pressure on water supply infrastructure, water resources in general and biodiversity. Innovative solutions thus prove to be necessary in making cities more resilient in the face of global changes. Urban wastewater management tends to be centrally organized, producing extensive pipe networks whose management raises economic as well as environmental concerns. Besides flood-related problems, the health and environmental impacts of this centralized model, leading to the overflow of polluted water at plant outfalls, are indeed substantial and non-sustainable. Implementing a decentralized approach to urban water management, by means of incorporating nature-based solutions, offers a tremendous opportunity for reconfiguring the cities of tomorrow. Effectively introducing a centralized urban water management protocol during rainy weather creates a number of decision-making, operational and scientific challenges: how to optimize the extent of centralization / decentralization policies to govern both stormwater and domestic wastewater?, what impacts are generated on the pollutant flows to be treated?, which treatment technologies can be envisaged depending on spatial constraints and end uses?, what are the resulting consequences from an economic or infrastructure management perspective? Such are just some of the considerations project managers must assess in devising their strategies.

Objectives:

The objectives of this project are to develop the appropriate decision-making framework to accompany authorities in sustainably managing urban waters through proposing a rational methodology to determine or distinguish urban waters on the basis of their catchment zones and spaces available for management closer to the source. Setting the boundaries of various nature-based solutions in terms of compactness and performance will serve to expand the choice of technologies to implement in urban settings.

Project organization:

• Topic 1: Development of a tool for optimizing the level of disconnection: adequacy of the disconnection point in light of local constraints, in order to mitigate environmental impacts.
• Topic 2: Refinement of a decision-making framework for selecting nature-based technologies at the scale of an entire region.
• Topic 3: Definition of the ancillary effects of implementing such an approach from the standpoint of the environment, the economy and human resources (specifically water management actors).

Anticipated benefits:

• Regional planning tools for the decentralized management of urban waters via nature-based solutions
• Limitation of overflows during rainy periods
• Improvement of cities’ resilience in coping with global changes.