How Evaluation of Green Roofs for Runoff Retention, Runoff Quality

Green roofs act as engineered stormwater systems that intercept rainfall on rooftops, reducing runoff volume and altering water quality compared to conventional roofs. A Toronto study found the green roof discharged 63% less total runoff, with summer reductions reaching 70-93%, while growing media leaching of phosphorus, aluminum, and copper required careful engineering. Performance varies by season and media composition, so designs must balance plant health with water quality goals. In this video: • The Purpose of Green Roof Runoff Retention • Precipitation as the Primary System Trigger • Quantifying Runoff Volume and Seasonal Retention • Chemical Composition and Nutrient Leaching • Engineering Media for Future Performance Chapters: 0:00 Introduction 0:24 The Purpose of Green Roof Runoff Retention 1:57 Precipitation as the Primary System Trigger 3:24 Quantifying Runoff Volume and Seasonal Retention 4:56 Chemical Composition and Nutrient Leaching 6:36 Engineering Media for Future Performance 9:55 Closing thoughts About How Everyday Systems Work: How water, power, transport, and everyday technology move from input to outcome. #GreenRoofWaterRetention #GreenRoofRunoffReduction #StormwaterManagement