Hybrid green-blue-gray decentralized urban drainage systems design, a simulation-optimization framework.

Area of Science:

• Environmental Engineering
• Urban Planning
• Water Resource Management

Background:

• Traditional gray infrastructure (pipe networks) faces challenges in reliability and sustainability.
• Green-blue infrastructure (GBI) offers multi-functionality and adaptability but requires integration with gray systems.
• Hybrid green-blue-gray infrastructures (HGBGI) combine the strengths of both approaches for advanced urban drainage.

Purpose of the Study:

• To develop and evaluate a simulation-optimization framework for designing HGBGI.
• To optimize urban drainage systems considering various HGBGI alternatives and centralization levels.
• To assess the resilience and sustainability of different HGBGI scenarios.

Main Methods:

• Characterization of the design site and base graph creation.
• Hydraulic design of different layouts using the hanging gardens algorithm.
• Multi-objective optimization for minimizing life cycle costs and maximizing GBI distribution.
• Resilience and sustainability evaluation using design storms.

Main Results:

• The proposed framework successfully optimizes urban drainage systems incorporating HGBGI.
• Evaluation of different degrees of centralization and GBI integration was performed.
• The case study in Ahvaz, Iran, demonstrated the framework's practical applicability.
• Trade-offs between cost, resilience, and sustainability were identified for decision-making.

Conclusions:

• The developed framework provides an effective tool for designing resilient and sustainable HGBGI.
• Optimized HGBGI can enhance urban drainage performance compared to traditional systems.
• Further research should explore long-term performance and broader implementation strategies.