A QGIS decision-support plugin for integrated urban water management using nature-based solutions

Coordinator :

Pascal MOLLE, Nicolas FORQUET

Active periode :

Since 2021

Financing

Office Français de la Biodiversité (OFB), Interreg Caraïbes, AFD, Agences de l’eau RMC et Adour Garonne

Partners :

DEEP (INSA Lyon), UFZ

Context

Historically, urban water (wastewater and rainwater) was regarded as a nuisance and a risk for the city. However, current scientific understanding recognises it as an opportunity and a resource to be valorised. In particular, it has been demonstrated that the deployment of decentralised management solutions can mitigate the risk of network failures in wet weather conditions and facilitate the reuse of treated water. When decentralisation is achieved through nature-based solutions, ecosystem services can also be provided to transform cities. However, the operational implementation of these solutions often remains opportunistic and isolated, failing to enhance the sustainability and resilience of cities. Decision-support tools could be leveraged to facilitate their development through territorial planning aimed at quantified objectives, by informing and clarifying the choices of operational decision-makers. ELAN (urban watEr pLanning scenArios for sustaiNable cities) aims to be one such tool.

Objective

The objective is to develop a GIS tool to assist with decision-making on the following issues:

• How to connect a new district / an area with no collective sewerage system (wastewater)?
• How to limit discharges in wet weather (wastewater and rainwater)?

ELAN is aimed at local authorities, design offices and, more generally, public decision-makers. It is a QGIS plugin. Therefore, ELAN will be free and open to all QGIS users. It will enable them to develop several scenarios and estimate their associated costs in order to enlighten their subsequent decisions.

Organisation

The ELAN system is based on a modular structure. The system will eventually comprise six processing modules, which will be used and interact with each other in different ways depending on the issue under consideration.

1. The network module allows for the creation of a comprehensive wastewater network where one does not currently exist or is not well-defined. The 3D layout includes the positioning of the discharge and lift stations.

2. The hydraulic module is used to calculate the contribution of each urban sub-catchment areas to the total volume of discharge produced by the catchment as a whole.

3. The process module is equipped with the capability to pre-dimension and simulate the operation of various nature-based systems for wastewater treatment or rainwater infiltration, in accordance with the constraints indicated by the user.

4. The reuse module will allow users to incorporate a component for reusing treated wastewater, thereby optimising the scenarios.

5. The assessment module to assess the scenarios created by the user based on several parameters (economic, technicity and robustness).

6. The comparison to enable the comparison of the different scenarios based on the criteria whose importance is defined by the user.

Organisation

• Facilitate the development of an integrated and a comprehensive urban water management in a given area.

Contact : pascal.molle(at)inrae.fr