Session C6 - At source stormwater management: community engagement

The Greater Montreal area in Quebec is experiencing an increase in both the intensity and frequency of extreme rainfall events, a direct consequence of climate change. Since 2022, rainfall events with a 100-year return period have occurred every year, exceeding the capacity of drainage networks and causing major flooding in low-lying areas. To enhance the resilience of the built environment, stormwater management strategies are already showing promising results. These include green and blue infrastructures, such as rain gardens, permeable pavements, and green or blue roofs. However, these strategies are mainly implemented on public properties, which limits their potential. This project aims to promote and facilitate the adoption of such measures on private property to better control stormwater runoff at the source in vulnerable areas. To do so, a case study is carried out on topographic depressions provided by two project partners: the cities of Longueuil and Montreal.

The pressure on urban drainage systems is increasing due to urbanisation and climate change, making decentralised rainwater management and the sponge city concept increasingly relevant. The city of Rostock aims to become a sponge city by 2080. Together with the University of Rostock, it has initiated a project to use GIS analyses to identify suitable locations for infiltration measures. The five participating housing companies collectively own a significant proportion of urban land — 57.84% of which is suitable for infiltration. Although several highly suitable contiguous areas were identified, implementation barriers emerged, including limited partner engagement, insufficient georeferenced data, unclear life-cycle costs and the structural constraints of existing buildings. Ongoing hydrological and hydraulic analyses aim to quantify the effects of decentralised measures. This project is laying the groundwork for water-sensitive urban development in Rostock, while also highlighting the need for binding strategies to support implementation on private land.

Researchers from the CAMELLIA project and community members from the Kipling Estate in London formed a collaboration to co-design blue-green infrastructure in the form of a community garden. While the community had long dreamed of creating a community garden, they were unaware of its potential to help prevent surface water flooding, nor how much drinking water would be used for its irrigation. The researchers created and facilitated a co-design process over three workshops, community garden visits, and pilot installations of raised planter beds and a rainwater collector. These activities increased the capacity of the community to understand water infrastructures and the logistics of community gardens ; and for the researchers to grasp the needs of the community for their garden. The community successfully secured funding from the Greater London Authority and established the Kipling Community Garden and Orchard. This demonstrates how academics and communities can work collaboratively to create blue-green infrastructures which fulfil the needs of both the local community and the wider infrastructural network. Co-design applied with care and sincerity gives people the skills and motivation to achieve goals in alignment with, but also greater than their initial ambitions.

This paper addresses community-based climate adaptation strategies in informal settlements of São Bento, Duque de Caxias, Brazil, focusing on water management through rainwater harvesting and Sustainable Urban Drainage Systems (SUDS). Informal settlements in the area face high flood risk and limited access to piped water, highlighting the need for local solutions. The study documents a partnership between the Federal University of Rio de Janeiro, a local NGO, and community associations to implement low-cost vertical cisterns and promote social participation. Fifty cisterns were installed across Vila Alzira and Novo São Bento, prioritizing socially vulnerable households. Training residents, particularly women, enabled both skill development and empowerment. Workshops identified flood-prone areas using local knowledge and drone imagery. The project integrates local perceptions into the planning of SUDS to improve water retention and mitigate flooding. Findings emphasize the importance of community engagement in enhancing urban resilience. The study contributes to understanding practical applications of Water Sensitive Urban Design in informal settlements. It highlights the potential of participatory approaches to support sustainable, inclusive climate adaptation.