What is the Green–Grey–Blue–Intelligent (GGBI) Framework?
The GGBI Framework provides a practical way to organize how we think about water and urban environments by recognizing four interacting domains: Green, Grey, Blue, and Intelligent. It highlights how ecological, engineered, aquatic, and intelligent elements can be combined to support resilience from local stormwater to watershed, estuarine, and coastal scales.
The Four Domains
Each domain represents a different way in which water, infrastructure, and environments interact. In practice, they overlap and must be considered together.
Green Infrastructure
Ecological and nature-based components that provide infiltration, storage, evapotranspiration, habitat, and co-benefits. Examples include rain gardens, green roofs, permeable surfaces, wetlands, and restored floodplains.
Grey Infrastructure
Engineered systems that convey, store, or control water, including pipes, culverts, tunnels, weirs, levees, floodwalls, pump stations, and coastal structures. Grey infrastructure often forms the backbone of urban and coastal protection.
Blue Environments
Rivers, estuaries, bays, coasts, and open water bodies where tides, waves, river flows, sediment, and ecosystems interact. Blue environments connect upland watersheds with coastal and marine settings.
Intelligent Infrastructure & Layer
The layer that brings together monitoring, data, models, analytics, AI tools, institutional knowledge, and communication. It helps interpret system behavior, evaluate options, and support adaptive planning and operations.
Interactions Across Scales
The GGBI Framework is particularly useful for thinking about how local interventions relate to larger-scale processes:
- Local scale: street and site-level stormwater, green infrastructure, and drainage systems.
- Neighborhood and city scale: urban flood pathways, drainage networks, storage, and combined green–grey measures.
- Watershed and basin scale: rainfall–runoff, river flows, sediment, and linkages to estuaries and coasts.
- Estuarine and coastal scale: tides, storm surge, waves, wetlands, channels, and coastal protection.
The Intelligent layer can support each scale by providing monitoring, modeling, analysis, and communication tools that help connect observations, understanding, and decisions.
How This Framework Is Used on This Site
On this website, the GGBI Framework serves as a central organizing idea for research, teaching, and applications in water and urban environments. It does not replace existing models or methods; instead, it provides a way to situate them within a broader context.
Other sections of the site draw on the four domains to:
- Summarize research on stormwater, watersheds, estuaries, and coasts.
- Describe applications such as flood resilience, climate adaptation, and nature-based solutions.
- Highlight teaching materials and conceptual diagrams used in graduate and undergraduate courses.