Professor Yu Kongjian Delivers Opening Keynote Address at Brazil's International Congress of Architecture and Urban Planning
From 4 to 6 September 2025, Brazil's capital Brasília hosted the International Congress of the Brazilian Council of Architecture and Urbanism (CAU-CI 2025). As one of Brazil's largest professional gatherings in architecture and urbanism, this edition centred on the theme ‘Architecture and Cities for All’. It drew nearly 4,000 attendees and over 120 speakers from 20 countries.
At the opening ceremony, Professor Yu Kongjian – a Chinese landscape architect, Vice Chairman of the Chinese Society for Urban Studies, member of the Climate Committee of the Chinese Society of Landscape Architecture, and Professor at Peking University – delivered a keynote address. Renowned globally for his ‘sponge city’ concept, Professor Yu Kongjian urged cities to abandon the outdated mindset of ‘fighting water’ in the face of climate change, advocating instead for ‘living in harmony with water’.
A landmark conference
Hosted by the Brazilian Council of Architecture and Urbanism (CAU/BR), CAU-CI 2025 coincided with the organisation's 15th anniversary. The conference returned to the symbolic city of Brasília – a modernist metropolis long regarded as an experimental laboratory for urban ideals. The programme was structured around three thematic pillars: ‘Pathways of Memory,’ ‘Places of Everyday Life,’ and ‘Trails of Innovation,’ encompassing heritage conservation, housing and social equity, and emerging technologies.
The distinguished guest list featured luminaries including Karl Fender (Australia), Sara Topelson (Mexico), Diana Wiesner (Colombia), Jorge Arditti (Argentina), Tye Farrow (Canada), Evelyn Lee (United States), alongside renowned Brazilian architects Gustavo Penna, Laura Penna, and Jô Vasconcellos. These diverse voices collectively resonated with the theme of ‘Shared for All’.
Yu Kongjian's Keynote Address: Paradigm Shift
In his address, Yu Kongjian stated unequivocally that traditional ‘grey infrastructure’ – relying on dams, pumping stations and concrete channels – is failing in the face of floods and extreme weather. ‘We can never conquer water; we must learn to coexist with it.’
His concept of Sponge Cities/Sponge Earth employs measures such as wetlands, sponge parks, permeable paving, green roofs, and floodable spaces to enable cities to naturally absorb, store, purify, and slowly release rainwater like a sponge. This approach not only mitigates flooding but also replenishes groundwater, improves water quality, cools the urban microclimate, and provides high-quality public spaces.
Three Principles of Sponge Cities/Sponge Earth
Yu Kongjian summarised three core principles: First, retention at source: increasing permeable surfaces and small-scale rainwater harvesting facilities; Second, runoff mitigation: restoring natural watercourses, constructing terraced landscapes, and decentralising flood detention areas; Third, downstream absorption: utilising wetlands, parks, and floodplains as natural expansion spaces during rainy seasons.
These measures represent not merely engineering solutions but a cultural shift, redefining water from an adversary to a resource and ally.
Brazilian Reality Resonates
Following severe flooding in Rio Grande do Sul in 2024, Brazil urgently requires new urban water management models. Weeks before the conference, Brazil's national television programme Fantástico featured a special report on how China implemented the Sponge City concept, demonstrating how natural systems effectively prevent disasters and enhance public quality of life (https://globoplay.globo.com/v/12590689).
Yu Kongjian noted that sponge city principles can be applied across Brazil's diverse environments—from the Amazon floodplains and semi-arid northeast to megacities like São Paulo and Rio de Janeiro.
Global Significance
The theory and practice of ‘sponge cities/sponge earth’ have transcended China and Brazil. In New York, the Waterfront Alliance regards it as a vital blueprint for addressing sea-level rise and extreme rainfall (Waterfront Alliance, 2025). During an interview on WBUR's Here & Now programme, Yu Kongjian emphasised: ‘We cannot fight water; we must learn to work with it.’ " (WBUR, 2025). CNN recently dedicated a documentary to Sponge Cities and Sponge Earth (https://edition.cnn.com/2024/08/13/style/china-sponge-cities-kongjian-yu-hnk-intl). This philosophy is resonating globally, reintegrating urban design into natural cycles.
The Conference Legacy
CAU-CI 2025 demonstrated that ‘architecture and cities for all’ transcends mere sloganism, embodying a profound social and environmental responsibility. Both international leaders and Brazilian architects and urban planners converged in Brasília upon a shared conviction: future architecture and cities must serve humanity and nature in tandem.
In Brasilia, a symbol of modernism, Yu Kongjian's address carried particular weight: 21st-century cities must renew their vision, shifting from concrete fortresses to ecological sponges, moving from ‘resisting nature’ to ‘collaborating with nature’.
Related coverage:
CAU/BR (2025a) Arquitetura e Urbanismo para Todos: Conferência Internacional CAU 2025 reúne profissionais de 20 países. Available at: https://caubr.gov.br/conferencia-internacional-cau-2025-comeca-nesta-quinta-feira-4-9 (Accessed: 11 September 2025).
Edit by Zhu Liangliang
