Unprecedented Retention Capabilities of Extensive Green Roofs—New Design Approaches and an Open-Source Model

Green roofs are a proven measure to increase evapotranspiration at the expense of runoff, thus complementing contemporary stormwater management efforts minimize pluvial flooding in cities. This effect has been quantified by numerous studies, ranging from experimental field campaigns modeling experiments and even combinations both. However, up until now, most green roof studies consider standard types dimensions, neglecting varying flow length substrate. For first time, we present comprehensive investigation that involves artificial rainfall under laboratory conditions (42 total). We slope. The novelty lies especially consideration lengths beyond 5 m non-declined roofs. part is complemented numerical modeling, employing open-source Catchment Modeling Framework (CMF). set-up for Darcy Richards calibrated utilizing multi-objective approach, considering both runoff hydraulic head. results demonstrate through maximizing minimizing slope, coefficient (i.e., percentage becomes runoff) 100 years design significantly decreased: ~30% values below 10%. These findings confirmed which proves its value terms achieved model skill (Kling-Gupta Efficiency 0.5 0.95 with median 0.78). Both data published as open software, respectively. Thus, this study provides new insights into high practical relevance, whilst being reproducible.