EuropeUrban Nature AtlasUrban Nature ExplorerCircular Water Catalyst – turning urban rainwater into a local resource

Community-led Circular Rainwater Retention for Resilient Urban Neighbourhoods

PROJECT SUMMARY

Circular Water Catalyst (CWC) helps Zugló and Szombathely shift from rapid urban rainwater drainage towards community-led, decentralised retention. Working around the Rákos-patak corridor in Zugló and the Gyöngyös-Perint water system in Szombathely, it addresses flooding, sewer overload, drought-stressed green areas, polluted runoff and weakened creek habitats by treating rainwater as a valuable local ecological and social resource.

The project combines hydro-social hotspot mapping and municipal approval baselines with digital decision support, inclusive Learning Communities and technical design. Residents, schools, municipal teams and experts will identify priority sites, compare nature-based solution portfolios in the Urban Nature Explorer, and turn selected scenarios into approval-ready pilots such as rain gardens, bioswales, infiltration beds, tree-based retention and riparian planting.

CWC will establish two Learning Communities and two localised Urban Nature Explorer environments, develop 12 digital scenarios and two community-backed action plans, and implement four pilot site clusters. It aims to create at least 1,000 m² of blue-green retention surfaces, redirect runoff from at least 3,500 m² of contributing area and deliver at least 250 m³ of design retention or infiltration capacity. A replication toolkit, peer learning and municipal continuation roadmaps will support transfer across Hungary and the wider Middle Danube region.

PHYSI’S ROLE

PHYSI leads Work Package 2 on baselines, hotspot mapping and localisation. It will develop the Atlas-based assessment protocol and hotspot-screening logic, use the Urban Nature Atlas to identify context-relevant nature-based solution options, and configure and calibrate two city-specific Urban Nature Explorer instances. These 2D/3D digital scenario environments will combine local spatial data, community knowledge and tailored indicators for rainwater retention, urban heat, biodiversity and local well-being, which will be inputs for technical and landscape planning, as well as physical implementation across four sites.

PHYSI also leads the UNE-supported co-design and action-planning task to engage local communities. It will help the two Learning Communities compare alternative portfolios, indicative costs and modelled impacts, document trade-offs and turn selected scenarios into locally backed action plans. PHYSI also contributes to technical diagnostics, quality assurance, technical monitoring support, as well as knowledge products for large-scale dissemination and transfer of the Atlas-to-Explorer workflow to follower municipalities in the Middle Danube region and beyond.

PARTNERSHIP

• Budapest Főváros XIV. Kerület Zugló Önkormányzata – Project Coordinator
• Municipality of Szombathely
• PHYSI
• OpenSpace Kft.
• West-Pannon Nonprofit Ltd.
• Association of Climate Friendly Municipalities (KTSZ)