Abstract
Urbanization intensifies hydrological challenges, including increased stormwater runoff, flooding, and water quality degradation. Nature-Based Solutions (NBS) offer a sustainable alternative to conventional grey infrastructure by mimicking natural hydrological processes. This study investigates the effectiveness of NBS for urban stormwater management in Portland, Oregon, a city recognized for its pioneering green infrastructure initiatives. Employing an integrated approach, we utilized the EPA Storm Water Management Model (SWMM) to quantify the hydrological performance of various NBS configurations (e.g., rain gardens, bioswales, permeable pavements) across a representative urban catchment under different storm events. Concurrently, an ecosystem services valuation framework was applied to assess the economic and environmental co-benefits, including avoided infrastructure costs, improved water quality, urban heat island mitigation, and enhanced aesthetic value. Results demonstrate that NBS significantly reduce peak flows (up to 70%) and total runoff volume (up to 55%), effectively mitigating flood risks and improving downstream water quality. The economic valuation revealed substantial monetary benefits, often exceeding the implementation costs, highlighting the cost-effectiveness and multi-functional advantages of NBS. This research provides empirical evidence supporting the widespread adoption of NBS as a cornerstone for resilient, sustainable, and human-centered urban development.
