Vegetated roofs for managing stormwater quantity in cold climate

Vegetated roofs, i.e. green were continuously measured for runoff to quantify their capacity manage stormwater in a field experiment southern Finland, with distinct seasonality and varying weather conditions. Attention was paid heavy storms study the potential mitigating urban flooding. In addition, impact of biochar amendment (10% v /v) on rainfall retention studied. Meadow vegetation established crushed brick based substrate either by introducing plants as seedlings seeds or using pre-grown readymade mats. Annual varied from 40% 70%. The highest retention, ca. 80%, found summer even though it rainiest season. Wintertime 30–40%. coarse enabled infiltration when frozen and, thus, roofs operated also winter. Heavy occurred mainly summer, season hydrologic performance resulting >80% peak attenuation slow release runoff. individual rain events, meadow largely function depth. However, weakly explained amount other variables, such intensity antecedent dry period, indicating difficulty capturing complex phenomena behind variable Biochar improved only slightly, at maximum 10%. empirical evidence this highlights vegetated feasible technology be applied management cold climate.