Hydrological Performance of Green Roofs in Urban Areas Exposed to Extreme Rainfall Events

Abstract

How do green roofs influence stormwater runoff in urban areas exposed to increasingly
extreme rainfall events? This paper evaluates hydrological performance of green roofs under
changing climatic conditions characterized by more frequent short-duration, high-intensity
precipitation. The study focuses on Central European urban environments, where rainfall
extremes increasingly challenge conventional drainage systems. The methodological approach
combines analysis of long-term precipitation time series with synthesis of theoretical
knowledge and experimental data on green roof hydrological responses to different rainfall
types. Results demonstrate that green roofs enhance rainfall retention and delay runoff
peaks during common and moderately intense precipitation events, reducing instantaneous
loads on urban drainage infrastructure. However, during extreme, rapidly occurring rainfall
events, retention capacity becomes limited, revealing functional thresholds. From an urban
planning and architectural perspective, these findings highlight the need for systematic
implementation of green roofs as an integral component of climate adaptation strategies
reducing urban vulnerability to rainfall extremes.