Optimization and trade-off framework for coupled green-grey infrastructure considering environmental performance

Area of Science:

• Environmental Engineering
• Urban Planning
• Water Resource Management

Background:

• Runoff control infrastructure is crucial for stormwater management but faces cost-effectiveness concerns.
• Traditional assessments often overlook environmental benefits beyond hydrology, focusing on two-dimensional hydrological and economic frameworks.

Purpose of the Study:

• To develop and integrate a novel carbon dioxide equivalent-based index for quantifying extra environmental benefits of runoff control infrastructure.
• To comprehensively evaluate and compare the hydrological, environmental, and economic effectiveness of green and grey infrastructure.

Main Methods:

• Quantified a carbon dioxide equivalent-based index to represent environmental benefits.
• Developed a three-dimensional assessment framework integrating hydrological (HF index), economic (CI index), and environmental (EROI index) aspects.
• Evaluated and traded off the performance of green and grey infrastructure.

Main Results:

• Grey infrastructure outperforms green infrastructure based solely on hydrological and economic factors.
• Green infrastructure demonstrates superior environmental performance (EROI index).
• In a three-dimensional framework, green infrastructure becomes comparable to grey infrastructure when environmental effectiveness is optimized.

Conclusions:

• A balanced composition of coupled green-grey infrastructure is necessary for optimal trade-offs between hydrological and environmental effectiveness.
• The study provides a basis for comparing green and grey infrastructure, considering environmental benefits (EROI) and hydrological performance (HF).