Question: In sustainable urban design, which metric is most useful for evaluating the effectiveness of green infrastructure in reducing stormwater runoff?

Wed, 06 May 2026 17:13:45 +0000

The Most Useful Metric for Evaluating Green Infrastructure’s Effectiveness in Reducing Stormwater Runoff As cities face increasing pressure from climate change, urbanization, and aging stormwater systems, sustainable urban design has emerged as a critical solution to manage stormwater runoff effectively. Green infrastructure—such as rain gardens, green roofs, permeable pavements, and bioswales—is widely promoted for its ability to mimic natural hydrology and reduce runoff volumes. But determining the true effectiveness of these interventions requires a reliable performance metric. Among the various indicators available, runoff reduction percentage stands out as the most valuable and widely adopted measure for evaluating the success of green infrastructure in mitigating stormwater challenges. ### Why Runoff Reduction Percentage Matters Runoff reduction percentage directly quantifies how much stormwater a green infrastructure system captures, infiltrates, or delays compared to a typical impervious surface under the same rainfall event. This metric is simple yet powerful, offering clear insight into both the volume of water mitigated and the functional performance of the installation.